import { Vector2, Loader, LoaderUtils, FileLoader, Color, SpotLight, PointLight, DirectionalLight, MeshBasicMaterial, sRGBEncoding, MeshPhysicalMaterial, TangentSpaceNormalMap, Quaternion, TextureLoader, ImageBitmapLoader, InterleavedBuffer, InterleavedBufferAttribute, BufferAttribute, LinearFilter, LinearMipmapLinearFilter, RepeatWrapping, PointsMaterial, Material, LineBasicMaterial, MeshStandardMaterial, DoubleSide, PropertyBinding, BufferGeometry, SkinnedMesh, Mesh, LineSegments, Line, LineLoop, Points, Group, PerspectiveCamera, MathUtils, OrthographicCamera, InterpolateLinear, AnimationClip, Bone, Object3D, Matrix4, Skeleton, TriangleFanDrawMode, NearestFilter, NearestMipmapNearestFilter, LinearMipmapNearestFilter, NearestMipmapLinearFilter, ClampToEdgeWrapping, MirroredRepeatWrapping, InterpolateDiscrete, FrontSide, Texture, TriangleStripDrawMode, VectorKeyframeTrack, QuaternionKeyframeTrack, NumberKeyframeTrack, Box3, Vector3, Sphere, Interpolant, Raycaster } from 'three';

/**
 * @desc 计算最佳线路时，需要转换数据
 */
function standardKeyPointsChanger(path) {
    // 转换 v1 的邻近点规则
    const keyPoints = [];
    const map = {};
    for (const item of path) {
        const node1 = map[JSON.stringify(item.begin)];
        const node2 = map[JSON.stringify(item.end)];
        if (!node1) {
            // 初始化
            map[JSON.stringify(item.begin)] = {
                id: JSON.stringify(item.begin),
                x: item.begin[0],
                y: item.begin[1],
                neighbours: [
                    {
                        id: JSON.stringify(item.end),
                        d: item.distance
                    }
                ]
            };
        }
        else {
            // 继续添加 neighbours
            node1.neighbours.push({
                id: JSON.stringify(item.end),
                d: item.distance
            });
        }
        if (!node2) {
            // 初始化
            map[JSON.stringify(item.end)] = {
                id: JSON.stringify(item.end),
                x: item.end[0],
                y: item.end[1],
                neighbours: [
                    {
                        id: JSON.stringify(item.begin),
                        d: item.distance
                    }
                ]
            };
        }
        else {
            // 继续添加 neighbours
            node2.neighbours.push({
                id: JSON.stringify(item.begin),
                d: item.distance
            });
        }
    }
    for (const key of Object.keys(map)) {
        keyPoints.push(map[key]);
    }
    return keyPoints;
}
/**
 * @desc 截取精度
 */
function myTruncate(point, precision = 3) {
    const [x, y] = point;
    if (isNaN(+x) || isNaN(+y)) {
        return [];
    }
    // 精度缩小
    return [
        parseFloat((+x).toFixed(precision)),
        parseFloat((+y).toFixed(precision))
    ];
}
function getDistance$1(p1, p2) {
    return Math.abs(Math.sqrt(Math.pow(p1.x - p2.x, 2) + Math.pow(p1.y - p2.y, 2)));
}
/**
 * @desc 把字符串转换成 float
 */
function parsePath(path) {
    const _parseArr = (arr) => {
        return [parseFloat(arr[0]), parseFloat(arr[1])];
    };
    for (const item of path) {
        Object.assign(item, {
            begin: _parseArr(item.begin),
            end: _parseArr(item.end),
            distance: parseFloat(item.distance)
        });
    }
    return path;
}

/**
 * A star
 * TODO:需要处理坐标为 threejs 规范的 Vector3 或 Vector2
 */
class AStar {
    constructor(path) {
        Object.defineProperty(this, "path", {
            enumerable: true,
            configurable: true,
            writable: true,
            value: path
        });
        Object.defineProperty(this, "sc", {
            enumerable: true,
            configurable: true,
            writable: true,
            value: void 0
        });
        Object.defineProperty(this, "keyPoints", {
            enumerable: true,
            configurable: true,
            writable: true,
            value: void 0
        });
        Object.defineProperty(this, "keyPointMap", {
            enumerable: true,
            configurable: true,
            writable: true,
            value: void 0
        });
        Object.defineProperty(this, "openList", {
            enumerable: true,
            configurable: true,
            writable: true,
            value: void 0
        });
        Object.defineProperty(this, "closeList", {
            enumerable: true,
            configurable: true,
            writable: true,
            value: void 0
        });
        Object.defineProperty(this, "invalidList", {
            enumerable: true,
            configurable: true,
            writable: true,
            value: void 0
        });
        Object.defineProperty(this, "searchCount", {
            enumerable: true,
            configurable: true,
            writable: true,
            value: void 0
        });
        Object.defineProperty(this, "beginTime", {
            enumerable: true,
            configurable: true,
            writable: true,
            value: void 0
        });
        Object.defineProperty(this, "endTime", {
            enumerable: true,
            configurable: true,
            writable: true,
            value: void 0
        });
        Object.defineProperty(this, "beginNode", {
            enumerable: true,
            configurable: true,
            writable: true,
            value: void 0
        });
        Object.defineProperty(this, "endNode", {
            enumerable: true,
            configurable: true,
            writable: true,
            value: void 0
        });
        Object.defineProperty(this, "beginVertical", {
            enumerable: true,
            configurable: true,
            writable: true,
            value: void 0
        });
        Object.defineProperty(this, "endVertical", {
            enumerable: true,
            configurable: true,
            writable: true,
            value: void 0
        });
        // 转换 path 的字符串为数字
        this.path = parsePath(this.path);
        // 单节点预估成本
        this.sc = 1;
        this.keyPoints = standardKeyPointsChanger(this.path);
        this.keyPointMap = {};
        // 将列表转换map对象
        for (let i = 0; i < this.keyPoints.length; i++) {
            const p = this.keyPoints[i];
            this.keyPointMap[p.id] = p;
        }
        this.openList = [];
        this.closeList = [];
        this.invalidList = [];
        this.searchCount = 0;
        this.beginTime = new Date();
        this.endTime = new Date();
    }
    shortestPath(beginNode, endNode) {
        const result = [];
        this.openList = []; // 已经知道，但未走过的节点
        this.closeList = []; // 走过的节点
        this.invalidList = []; // 失效的点
        this.searchCount = 0;
        this.beginTime = new Date();
        beginNode.parent = null;
        beginNode.d = 0;
        this.beginNode = beginNode;
        this.endNode = endNode;
        this.closeList.push(this.beginNode);
        // eslint-disable-next-line no-constant-condition
        while (true) {
            if (this.closeList.length === 0) {
                break;
            }
            this.searchCount++;
            let currNode = this.closeList[this.closeList.length - 1];
            if (currNode.id === endNode.id) {
                // 已经抵达目的地, 按照parent往回追溯，返回结果
                while (currNode && currNode !== null) {
                    result.unshift(currNode);
                    currNode = currNode.parent;
                }
                break;
            }
            if (currNode.neighbours && currNode.neighbours.length > 0) {
                for (let i = 0; i < currNode.neighbours.length; i++) {
                    const nb = currNode.neighbours[i];
                    const tmpNode = this.keyPointMap[nb.id];
                    // 周围节点必须满足三个条件：
                    // 1.这个点是合法的，什么叫合法？这里简单的就是可以通行的，不能是障碍物
                    if (!tmpNode || this.contain(this.invalidList, tmpNode)) {
                        continue;
                    }
                    // 2.这个点不能在close表中
                    if (this.contain(this.closeList, tmpNode)) {
                        continue;
                    }
                    // 3.这个点不能在open表中
                    if (this.contain(this.openList, tmpNode)) {
                        continue;
                    }
                    tmpNode.d = nb.d; // 相邻点距离
                    tmpNode.parent = currNode;
                    tmpNode.cost = this.f(tmpNode);
                    this.openList.push(tmpNode);
                }
            }
            if (this.openList.length > 0) {
                // 计算open列表cost值最低的节点minNode
                let minNode = null;
                for (let i = 0; i < this.openList.length; i++) {
                    const tmp = this.openList[i];
                    if (minNode === null || minNode.cost > tmp.cost) {
                        minNode = tmp;
                    }
                }
                // minNode从open表中删除加入close表
                this.remove(this.openList, minNode);
                this.closeList.push(minNode);
            }
            else {
                // 如果openList没有节点了，那么取上一个closeList中的节点，继续循环
                // 该节点没有有效的邻近节点，移到失效列表
                this.invalidList.push(currNode);
                this.remove(this.closeList, currNode);
            }
            if (this.searchCount > 500000) {
                // 避免死循环
                break;
            }
        }
        this.endTime = new Date();
        return result;
    }
    contain(nodes, node) {
        let result = false;
        nodes.forEach(function (item) {
            if (item.id === node.id) {
                result = true;
            }
        });
        return result;
    }
    remove(nodes, node) {
        let move = false;
        for (let i = 0; i < nodes.length; i++) {
            if (move) {
                nodes[i - 1] = nodes[i];
            }
            if (node.id === nodes[i].id) {
                move = true;
            }
        }
        if (move) {
            nodes.length -= 1;
        }
    }
    // 节点代价
    f(n) {
        return this.g(n) + this.h(n);
    }
    // 初始节点到n节点的明确代价
    g(n) {
        let result = 0;
        let currNode = n;
        while (currNode && currNode !== null) {
            result += currNode.d;
            currNode = currNode.parent;
        }
        return result;
    }
    // 是n节点到目标点的预估代价；
    h(n) {
        return this.euclidianCost(n, this.endNode);
    }
    // //麦哈顿估算法
    // manhattanCost(begin, end) {
    //   return (
    //     Math.abs(begin.x - end.x) * this.sc + Math.abs(begin.y + end.y) * this.sc
    //   );
    // }
    // 几何估价法
    euclidianCost(begin, end) {
        const dx = begin.x - end.x;
        const dy = begin.y - end.y;
        return Math.sqrt(dx * dx + dy * dy) * this.sc;
    }
    // //对角线估价法
    // diagonalCost(begin, end) {
    //   var dx = Math.abs(begin.x - end.x);
    //   var dy = Math.abs(begin.y - end.y);
    //   var diag = Math.min(dx, dy);
    //   var straight = dx + dy;
    //   return this.sc * diag + this.sc * (straight - 2 * diag);
    // }
    getNearest(point, isBegin = true) {
        let tempItem;
        let nearPoint;
        let vertical;
        let dist = Infinity;
        for (let i = 0; i < this.path.length; i++) {
            tempItem = this.path[i];
            const { dist: tempDist, point: tempPoint, vertical: tempVertical } = this.nearestPointOnLine(tempItem.begin, tempItem.end, point);
            if (tempDist < dist) {
                dist = tempDist;
                nearPoint = tempPoint;
                vertical = tempVertical;
            }
        }
        // this.drawNearLine(nearItem.begin, nearItem.end, _name('rnFindLineNear'));
        // this.drawNearPoint(nearPoint as [number, number], _name('rnFindPointNear'));
        // vertical &&
        //   this.drawVertical(
        //     vertical as [number, number],
        //     _name('rnFindPointVertical')
        //   );
        return { point: nearPoint, vertical };
    }
    /**
     * @desc 最佳线路计算
     */
    calcShortestPath(begin, end) {
        const { point: beginPoint, vertical: beginVertical } = this.getNearest(begin, true);
        const { point: endPoint, vertical: endVertical } = this.getNearest(end, false);
        // 更新起点/终点垂点
        this.beginVertical = beginVertical;
        this.endVertical = endVertical;
        const standardBeginPoint = this.keyPoints.find(_ => _.id === JSON.stringify(beginPoint));
        const standardEndPoint = this.keyPoints.find(_ => _.id === JSON.stringify(endPoint));
        let result = this.shortestPath(standardBeginPoint, standardEndPoint);
        // 进行线路优化
        result = this.trackOptimize(result);
        return result;
    }
    /**
     * @desc 线路优化
     */
    trackOptimize(trackPoints) {
        if (trackPoints.length >= 2) {
            // 加工，判断头尾是否加上垂点
            // 有垂点才进行判断追加，没有垂点，就不进行添加
            if (this.beginVertical) {
                const beginV = new Vector2(this.beginVertical[0], this.beginVertical[1]);
                if (this.isInLine(trackPoints[0], trackPoints[1], beginV, 2)) {
                    console.log('起点垂点在导航线上，shift 去除连接起点，后续 unshift 起点垂点');
                    trackPoints.shift();
                }
                trackPoints.unshift(beginV);
            }
            if (this.endVertical) {
                const endV = new Vector2(this.endVertical[0], this.endVertical[1]);
                if (this.isInLine(trackPoints[trackPoints.length - 1], trackPoints[trackPoints.length - 2], endV, 2)) {
                    console.log('终点垂点在导航线上，pop 去除连接终点，后续 push 终点垂点');
                    trackPoints.pop();
                }
                trackPoints.push(endV);
            }
        }
        return trackPoints;
    }
    /**
     * @desc 获取点到各个线段上最近的一条线段和相关信息
     * 需要返回距离，来筛选最近的线段
     * dist：一般来说是点和垂点的距离 dist。但是需要判断如果垂点在直线外部，就计算点到线段两端的距离 min dist
     * 拿到 dist 循环筛选出最近的即可。
     * point：表示距离点最近的线段端点，主要用来a星算法
     * vertical：表示垂点，主要用来补充线段
     */
    nearestPointOnLine(begin, end, p) {
        const _getNearPointByLineBeginEnd = () => {
            const arr = [
                {
                    point: begin,
                    dist: getDistance$1(new Vector2(begin[0], begin[1]), new Vector2(p[0], p[1]))
                },
                {
                    point: end,
                    dist: getDistance$1(new Vector2(end[0], end[1]), new Vector2(p[0], p[1]))
                }
            ];
            arr.sort((a, b) => a.dist - b.dist);
            return arr[0];
        };
        let point = [0, 0];
        let vertical = null;
        let dist = 0;
        // 获取垂足
        const { x, y } = this.getVerticalPoint(new Vector2(begin[0], begin[1]), new Vector2(end[0], end[1]), new Vector2(p[0], p[1]));
        // 判断垂足是否在线上，在线上直接返回，不在线上，返回距离垂足最近的点
        const isInline = this.isInLine(new Vector2(begin[0], begin[1]), new Vector2(end[0], end[1]), new Vector2(x, y), 2);
        const { point: _point, dist: _dist } = _getNearPointByLineBeginEnd();
        point = _point;
        if (isInline) {
            vertical = [x, y];
            dist = getDistance$1(new Vector2(p[0], p[1]), new Vector2(x, y));
        }
        else {
            vertical = null;
            point = _point;
            dist = _dist;
        }
        return {
            vertical,
            point,
            dist
        };
    }
    /**
     * @desc 求点C在由点A、点B组成的直线的垂点
     */
    getVerticalPoint(p1, p2, p) {
        // 直线方程：Ax + By + C = 0
        const A = p2.y - p1.y;
        const B = p1.x - p2.x;
        const C = p2.x * p1.y - p1.x * p2.y;
        const tmp = A * A + B * B;
        let x = (B * B * p.x - A * B * p.y - A * C) / tmp; // 垂点的X坐标
        let y = (A * A * p.y - A * B * p.x - B * C) / tmp; // 垂点的Y坐标
        // 缩小精度
        const [x1, y1] = myTruncate([x, y]);
        x = x1;
        y = y1;
        return { x, y };
    }
    /**
     * @desc 计算两个坐标连线后的倾斜角度
     */
    getAngle(p1, p2) {
        const radian = Math.atan2(p2.y - p1.y, p2.x - p1.x);
        const angle = radian * (180 / Math.PI);
        return {
            radian,
            angle
        };
    }
    /**
     * @desc 判断p是否在p1和p2的线段内
     */
    isInLine(p1, p2, p, offsetAngle = 0) {
        if (!p1 || !p2 || !p) {
            return false;
        }
        // 允许一定的上下偏差，由于一些精度计算原因，可能点无法被识别在线段上
        const diffAngle = Math.floor(this.getAngle(p1, p).angle) -
            Math.floor(this.getAngle(p, p2).angle);
        if (offsetAngle === 0) {
            return diffAngle === 0;
        }
        else {
            // [-offsetAngle,offsetAngle]
            return diffAngle >= -offsetAngle && diffAngle <= offsetAngle;
        }
    }
}

class GLTFLoader extends Loader {

	constructor( manager ) {

		super( manager );

		this.dracoLoader = null;
		this.ktx2Loader = null;
		this.meshoptDecoder = null;

		this.pluginCallbacks = [];

		this.register( function ( parser ) {

			return new GLTFMaterialsClearcoatExtension( parser );

		} );

		this.register( function ( parser ) {

			return new GLTFTextureBasisUExtension( parser );

		} );

		this.register( function ( parser ) {

			return new GLTFTextureWebPExtension( parser );

		} );

		this.register( function ( parser ) {

			return new GLTFMaterialsSheenExtension( parser );

		} );

		this.register( function ( parser ) {

			return new GLTFMaterialsTransmissionExtension( parser );

		} );

		this.register( function ( parser ) {

			return new GLTFMaterialsVolumeExtension( parser );

		} );

		this.register( function ( parser ) {

			return new GLTFMaterialsIorExtension( parser );

		} );

		this.register( function ( parser ) {

			return new GLTFMaterialsEmissiveStrengthExtension( parser );

		} );

		this.register( function ( parser ) {

			return new GLTFMaterialsSpecularExtension( parser );

		} );

		this.register( function ( parser ) {

			return new GLTFMaterialsIridescenceExtension( parser );

		} );

		this.register( function ( parser ) {

			return new GLTFLightsExtension( parser );

		} );

		this.register( function ( parser ) {

			return new GLTFMeshoptCompression( parser );

		} );

	}

	load( url, onLoad, onProgress, onError ) {

		const scope = this;

		let resourcePath;

		if ( this.resourcePath !== '' ) {

			resourcePath = this.resourcePath;

		} else if ( this.path !== '' ) {

			resourcePath = this.path;

		} else {

			resourcePath = LoaderUtils.extractUrlBase( url );

		}

		// Tells the LoadingManager to track an extra item, which resolves after
		// the model is fully loaded. This means the count of items loaded will
		// be incorrect, but ensures manager.onLoad() does not fire early.
		this.manager.itemStart( url );

		const _onError = function ( e ) {

			if ( onError ) {

				onError( e );

			} else {

				console.error( e );

			}

			scope.manager.itemError( url );
			scope.manager.itemEnd( url );

		};

		const loader = new FileLoader( this.manager );

		loader.setPath( this.path );
		loader.setResponseType( 'arraybuffer' );
		loader.setRequestHeader( this.requestHeader );
		loader.setWithCredentials( this.withCredentials );

		loader.load( url, function ( data ) {

			try {

				scope.parse( data, resourcePath, function ( gltf ) {

					onLoad( gltf );

					scope.manager.itemEnd( url );

				}, _onError );

			} catch ( e ) {

				_onError( e );

			}

		}, onProgress, _onError );

	}

	setDRACOLoader( dracoLoader ) {

		this.dracoLoader = dracoLoader;
		return this;

	}

	setDDSLoader() {

		throw new Error(

			'THREE.GLTFLoader: "MSFT_texture_dds" no longer supported. Please update to "KHR_texture_basisu".'

		);

	}

	setKTX2Loader( ktx2Loader ) {

		this.ktx2Loader = ktx2Loader;
		return this;

	}

	setMeshoptDecoder( meshoptDecoder ) {

		this.meshoptDecoder = meshoptDecoder;
		return this;

	}

	register( callback ) {

		if ( this.pluginCallbacks.indexOf( callback ) === - 1 ) {

			this.pluginCallbacks.push( callback );

		}

		return this;

	}

	unregister( callback ) {

		if ( this.pluginCallbacks.indexOf( callback ) !== - 1 ) {

			this.pluginCallbacks.splice( this.pluginCallbacks.indexOf( callback ), 1 );

		}

		return this;

	}

	parse( data, path, onLoad, onError ) {

		let content;
		const extensions = {};
		const plugins = {};

		if ( typeof data === 'string' ) {

			content = data;

		} else {

			const magic = LoaderUtils.decodeText( new Uint8Array( data, 0, 4 ) );

			if ( magic === BINARY_EXTENSION_HEADER_MAGIC ) {

				try {

					extensions[ EXTENSIONS.KHR_BINARY_GLTF ] = new GLTFBinaryExtension( data );

				} catch ( error ) {

					if ( onError ) onError( error );
					return;

				}

				content = extensions[ EXTENSIONS.KHR_BINARY_GLTF ].content;

			} else {

				content = LoaderUtils.decodeText( new Uint8Array( data ) );

			}

		}

		const json = JSON.parse( content );

		if ( json.asset === undefined || json.asset.version[ 0 ] < 2 ) {

			if ( onError ) onError( new Error( 'THREE.GLTFLoader: Unsupported asset. glTF versions >=2.0 are supported.' ) );
			return;

		}

		const parser = new GLTFParser( json, {

			path: path || this.resourcePath || '',
			crossOrigin: this.crossOrigin,
			requestHeader: this.requestHeader,
			manager: this.manager,
			ktx2Loader: this.ktx2Loader,
			meshoptDecoder: this.meshoptDecoder

		} );

		parser.fileLoader.setRequestHeader( this.requestHeader );

		for ( let i = 0; i < this.pluginCallbacks.length; i ++ ) {

			const plugin = this.pluginCallbacks[ i ]( parser );
			plugins[ plugin.name ] = plugin;

			// Workaround to avoid determining as unknown extension
			// in addUnknownExtensionsToUserData().
			// Remove this workaround if we move all the existing
			// extension handlers to plugin system
			extensions[ plugin.name ] = true;

		}

		if ( json.extensionsUsed ) {

			for ( let i = 0; i < json.extensionsUsed.length; ++ i ) {

				const extensionName = json.extensionsUsed[ i ];
				const extensionsRequired = json.extensionsRequired || [];

				switch ( extensionName ) {

					case EXTENSIONS.KHR_MATERIALS_UNLIT:
						extensions[ extensionName ] = new GLTFMaterialsUnlitExtension();
						break;

					case EXTENSIONS.KHR_MATERIALS_PBR_SPECULAR_GLOSSINESS:
						extensions[ extensionName ] = new GLTFMaterialsPbrSpecularGlossinessExtension();
						break;

					case EXTENSIONS.KHR_DRACO_MESH_COMPRESSION:
						extensions[ extensionName ] = new GLTFDracoMeshCompressionExtension( json, this.dracoLoader );
						break;

					case EXTENSIONS.KHR_TEXTURE_TRANSFORM:
						extensions[ extensionName ] = new GLTFTextureTransformExtension();
						break;

					case EXTENSIONS.KHR_MESH_QUANTIZATION:
						extensions[ extensionName ] = new GLTFMeshQuantizationExtension();
						break;

					default:

						if ( extensionsRequired.indexOf( extensionName ) >= 0 && plugins[ extensionName ] === undefined ) {

							console.warn( 'THREE.GLTFLoader: Unknown extension "' + extensionName + '".' );

						}

				}

			}

		}

		parser.setExtensions( extensions );
		parser.setPlugins( plugins );
		parser.parse( onLoad, onError );

	}

	parseAsync( data, path ) {

		const scope = this;

		return new Promise( function ( resolve, reject ) {

			scope.parse( data, path, resolve, reject );

		} );

	}

}

/* GLTFREGISTRY */

function GLTFRegistry() {

	let objects = {};

	return	{

		get: function ( key ) {

			return objects[ key ];

		},

		add: function ( key, object ) {

			objects[ key ] = object;

		},

		remove: function ( key ) {

			delete objects[ key ];

		},

		removeAll: function () {

			objects = {};

		}

	};

}

/*********************************/
/********** EXTENSIONS ***********/
/*********************************/

const EXTENSIONS = {
	KHR_BINARY_GLTF: 'KHR_binary_glTF',
	KHR_DRACO_MESH_COMPRESSION: 'KHR_draco_mesh_compression',
	KHR_LIGHTS_PUNCTUAL: 'KHR_lights_punctual',
	KHR_MATERIALS_CLEARCOAT: 'KHR_materials_clearcoat',
	KHR_MATERIALS_IOR: 'KHR_materials_ior',
	KHR_MATERIALS_PBR_SPECULAR_GLOSSINESS: 'KHR_materials_pbrSpecularGlossiness',
	KHR_MATERIALS_SHEEN: 'KHR_materials_sheen',
	KHR_MATERIALS_SPECULAR: 'KHR_materials_specular',
	KHR_MATERIALS_TRANSMISSION: 'KHR_materials_transmission',
	KHR_MATERIALS_IRIDESCENCE: 'KHR_materials_iridescence',
	KHR_MATERIALS_UNLIT: 'KHR_materials_unlit',
	KHR_MATERIALS_VOLUME: 'KHR_materials_volume',
	KHR_TEXTURE_BASISU: 'KHR_texture_basisu',
	KHR_TEXTURE_TRANSFORM: 'KHR_texture_transform',
	KHR_MESH_QUANTIZATION: 'KHR_mesh_quantization',
	KHR_MATERIALS_EMISSIVE_STRENGTH: 'KHR_materials_emissive_strength',
	EXT_TEXTURE_WEBP: 'EXT_texture_webp',
	EXT_MESHOPT_COMPRESSION: 'EXT_meshopt_compression'
};

/**
 * Punctual Lights Extension
 *
 * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_lights_punctual
 */
class GLTFLightsExtension {

	constructor( parser ) {

		this.parser = parser;
		this.name = EXTENSIONS.KHR_LIGHTS_PUNCTUAL;

		// Object3D instance caches
		this.cache = { refs: {}, uses: {} };

	}

	_markDefs() {

		const parser = this.parser;
		const nodeDefs = this.parser.json.nodes || [];

		for ( let nodeIndex = 0, nodeLength = nodeDefs.length; nodeIndex < nodeLength; nodeIndex ++ ) {

			const nodeDef = nodeDefs[ nodeIndex ];

			if ( nodeDef.extensions
					&& nodeDef.extensions[ this.name ]
					&& nodeDef.extensions[ this.name ].light !== undefined ) {

				parser._addNodeRef( this.cache, nodeDef.extensions[ this.name ].light );

			}

		}

	}

	_loadLight( lightIndex ) {

		const parser = this.parser;
		const cacheKey = 'light:' + lightIndex;
		let dependency = parser.cache.get( cacheKey );

		if ( dependency ) return dependency;

		const json = parser.json;
		const extensions = ( json.extensions && json.extensions[ this.name ] ) || {};
		const lightDefs = extensions.lights || [];
		const lightDef = lightDefs[ lightIndex ];
		let lightNode;

		const color = new Color( 0xffffff );

		if ( lightDef.color !== undefined ) color.fromArray( lightDef.color );

		const range = lightDef.range !== undefined ? lightDef.range : 0;

		switch ( lightDef.type ) {

			case 'directional':
				lightNode = new DirectionalLight( color );
				lightNode.target.position.set( 0, 0, - 1 );
				lightNode.add( lightNode.target );
				break;

			case 'point':
				lightNode = new PointLight( color );
				lightNode.distance = range;
				break;

			case 'spot':
				lightNode = new SpotLight( color );
				lightNode.distance = range;
				// Handle spotlight properties.
				lightDef.spot = lightDef.spot || {};
				lightDef.spot.innerConeAngle = lightDef.spot.innerConeAngle !== undefined ? lightDef.spot.innerConeAngle : 0;
				lightDef.spot.outerConeAngle = lightDef.spot.outerConeAngle !== undefined ? lightDef.spot.outerConeAngle : Math.PI / 4.0;
				lightNode.angle = lightDef.spot.outerConeAngle;
				lightNode.penumbra = 1.0 - lightDef.spot.innerConeAngle / lightDef.spot.outerConeAngle;
				lightNode.target.position.set( 0, 0, - 1 );
				lightNode.add( lightNode.target );
				break;

			default:
				throw new Error( 'THREE.GLTFLoader: Unexpected light type: ' + lightDef.type );

		}

		// Some lights (e.g. spot) default to a position other than the origin. Reset the position
		// here, because node-level parsing will only override position if explicitly specified.
		lightNode.position.set( 0, 0, 0 );

		lightNode.decay = 2;

		if ( lightDef.intensity !== undefined ) lightNode.intensity = lightDef.intensity;

		lightNode.name = parser.createUniqueName( lightDef.name || ( 'light_' + lightIndex ) );

		dependency = Promise.resolve( lightNode );

		parser.cache.add( cacheKey, dependency );

		return dependency;

	}

	createNodeAttachment( nodeIndex ) {

		const self = this;
		const parser = this.parser;
		const json = parser.json;
		const nodeDef = json.nodes[ nodeIndex ];
		const lightDef = ( nodeDef.extensions && nodeDef.extensions[ this.name ] ) || {};
		const lightIndex = lightDef.light;

		if ( lightIndex === undefined ) return null;

		return this._loadLight( lightIndex ).then( function ( light ) {

			return parser._getNodeRef( self.cache, lightIndex, light );

		} );

	}

}

/**
 * Unlit Materials Extension
 *
 * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_materials_unlit
 */
class GLTFMaterialsUnlitExtension {

	constructor() {

		this.name = EXTENSIONS.KHR_MATERIALS_UNLIT;

	}

	getMaterialType() {

		return MeshBasicMaterial;

	}

	extendParams( materialParams, materialDef, parser ) {

		const pending = [];

		materialParams.color = new Color( 1.0, 1.0, 1.0 );
		materialParams.opacity = 1.0;

		const metallicRoughness = materialDef.pbrMetallicRoughness;

		if ( metallicRoughness ) {

			if ( Array.isArray( metallicRoughness.baseColorFactor ) ) {

				const array = metallicRoughness.baseColorFactor;

				materialParams.color.fromArray( array );
				materialParams.opacity = array[ 3 ];

			}

			if ( metallicRoughness.baseColorTexture !== undefined ) {

				pending.push( parser.assignTexture( materialParams, 'map', metallicRoughness.baseColorTexture, sRGBEncoding ) );

			}

		}

		return Promise.all( pending );

	}

}

/**
 * Materials Emissive Strength Extension
 *
 * Specification: https://github.com/KhronosGroup/glTF/blob/5768b3ce0ef32bc39cdf1bef10b948586635ead3/extensions/2.0/Khronos/KHR_materials_emissive_strength/README.md
 */
class GLTFMaterialsEmissiveStrengthExtension {

	constructor( parser ) {

		this.parser = parser;
		this.name = EXTENSIONS.KHR_MATERIALS_EMISSIVE_STRENGTH;

	}

	extendMaterialParams( materialIndex, materialParams ) {

		const parser = this.parser;
		const materialDef = parser.json.materials[ materialIndex ];

		if ( ! materialDef.extensions || ! materialDef.extensions[ this.name ] ) {

			return Promise.resolve();

		}

		const emissiveStrength = materialDef.extensions[ this.name ].emissiveStrength;

		if ( emissiveStrength !== undefined ) {

			materialParams.emissiveIntensity = emissiveStrength;

		}

		return Promise.resolve();

	}

}

/**
 * Clearcoat Materials Extension
 *
 * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_materials_clearcoat
 */
class GLTFMaterialsClearcoatExtension {

	constructor( parser ) {

		this.parser = parser;
		this.name = EXTENSIONS.KHR_MATERIALS_CLEARCOAT;

	}

	getMaterialType( materialIndex ) {

		const parser = this.parser;
		const materialDef = parser.json.materials[ materialIndex ];

		if ( ! materialDef.extensions || ! materialDef.extensions[ this.name ] ) return null;

		return MeshPhysicalMaterial;

	}

	extendMaterialParams( materialIndex, materialParams ) {

		const parser = this.parser;
		const materialDef = parser.json.materials[ materialIndex ];

		if ( ! materialDef.extensions || ! materialDef.extensions[ this.name ] ) {

			return Promise.resolve();

		}

		const pending = [];

		const extension = materialDef.extensions[ this.name ];

		if ( extension.clearcoatFactor !== undefined ) {

			materialParams.clearcoat = extension.clearcoatFactor;

		}

		if ( extension.clearcoatTexture !== undefined ) {

			pending.push( parser.assignTexture( materialParams, 'clearcoatMap', extension.clearcoatTexture ) );

		}

		if ( extension.clearcoatRoughnessFactor !== undefined ) {

			materialParams.clearcoatRoughness = extension.clearcoatRoughnessFactor;

		}

		if ( extension.clearcoatRoughnessTexture !== undefined ) {

			pending.push( parser.assignTexture( materialParams, 'clearcoatRoughnessMap', extension.clearcoatRoughnessTexture ) );

		}

		if ( extension.clearcoatNormalTexture !== undefined ) {

			pending.push( parser.assignTexture( materialParams, 'clearcoatNormalMap', extension.clearcoatNormalTexture ) );

			if ( extension.clearcoatNormalTexture.scale !== undefined ) {

				const scale = extension.clearcoatNormalTexture.scale;

				materialParams.clearcoatNormalScale = new Vector2( scale, scale );

			}

		}

		return Promise.all( pending );

	}

}

/**
 * Iridescence Materials Extension
 *
 * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_materials_iridescence
 */
class GLTFMaterialsIridescenceExtension {

	constructor( parser ) {

		this.parser = parser;
		this.name = EXTENSIONS.KHR_MATERIALS_IRIDESCENCE;

	}

	getMaterialType( materialIndex ) {

		const parser = this.parser;
		const materialDef = parser.json.materials[ materialIndex ];

		if ( ! materialDef.extensions || ! materialDef.extensions[ this.name ] ) return null;

		return MeshPhysicalMaterial;

	}

	extendMaterialParams( materialIndex, materialParams ) {

		const parser = this.parser;
		const materialDef = parser.json.materials[ materialIndex ];

		if ( ! materialDef.extensions || ! materialDef.extensions[ this.name ] ) {

			return Promise.resolve();

		}

		const pending = [];

		const extension = materialDef.extensions[ this.name ];

		if ( extension.iridescenceFactor !== undefined ) {

			materialParams.iridescence = extension.iridescenceFactor;

		}

		if ( extension.iridescenceTexture !== undefined ) {

			pending.push( parser.assignTexture( materialParams, 'iridescenceMap', extension.iridescenceTexture ) );

		}

		if ( extension.iridescenceIor !== undefined ) {

			materialParams.iridescenceIOR = extension.iridescenceIor;

		}

		if ( materialParams.iridescenceThicknessRange === undefined ) {

			materialParams.iridescenceThicknessRange = [ 100, 400 ];

		}

		if ( extension.iridescenceThicknessMinimum !== undefined ) {

			materialParams.iridescenceThicknessRange[ 0 ] = extension.iridescenceThicknessMinimum;

		}

		if ( extension.iridescenceThicknessMaximum !== undefined ) {

			materialParams.iridescenceThicknessRange[ 1 ] = extension.iridescenceThicknessMaximum;

		}

		if ( extension.iridescenceThicknessTexture !== undefined ) {

			pending.push( parser.assignTexture( materialParams, 'iridescenceThicknessMap', extension.iridescenceThicknessTexture ) );

		}

		return Promise.all( pending );

	}

}

/**
 * Sheen Materials Extension
 *
 * Specification: https://github.com/KhronosGroup/glTF/tree/main/extensions/2.0/Khronos/KHR_materials_sheen
 */
class GLTFMaterialsSheenExtension {

	constructor( parser ) {

		this.parser = parser;
		this.name = EXTENSIONS.KHR_MATERIALS_SHEEN;

	}

	getMaterialType( materialIndex ) {

		const parser = this.parser;
		const materialDef = parser.json.materials[ materialIndex ];

		if ( ! materialDef.extensions || ! materialDef.extensions[ this.name ] ) return null;

		return MeshPhysicalMaterial;

	}

	extendMaterialParams( materialIndex, materialParams ) {

		const parser = this.parser;
		const materialDef = parser.json.materials[ materialIndex ];

		if ( ! materialDef.extensions || ! materialDef.extensions[ this.name ] ) {

			return Promise.resolve();

		}

		const pending = [];

		materialParams.sheenColor = new Color( 0, 0, 0 );
		materialParams.sheenRoughness = 0;
		materialParams.sheen = 1;

		const extension = materialDef.extensions[ this.name ];

		if ( extension.sheenColorFactor !== undefined ) {

			materialParams.sheenColor.fromArray( extension.sheenColorFactor );

		}

		if ( extension.sheenRoughnessFactor !== undefined ) {

			materialParams.sheenRoughness = extension.sheenRoughnessFactor;

		}

		if ( extension.sheenColorTexture !== undefined ) {

			pending.push( parser.assignTexture( materialParams, 'sheenColorMap', extension.sheenColorTexture, sRGBEncoding ) );

		}

		if ( extension.sheenRoughnessTexture !== undefined ) {

			pending.push( parser.assignTexture( materialParams, 'sheenRoughnessMap', extension.sheenRoughnessTexture ) );

		}

		return Promise.all( pending );

	}

}

/**
 * Transmission Materials Extension
 *
 * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_materials_transmission
 * Draft: https://github.com/KhronosGroup/glTF/pull/1698
 */
class GLTFMaterialsTransmissionExtension {

	constructor( parser ) {

		this.parser = parser;
		this.name = EXTENSIONS.KHR_MATERIALS_TRANSMISSION;

	}

	getMaterialType( materialIndex ) {

		const parser = this.parser;
		const materialDef = parser.json.materials[ materialIndex ];

		if ( ! materialDef.extensions || ! materialDef.extensions[ this.name ] ) return null;

		return MeshPhysicalMaterial;

	}

	extendMaterialParams( materialIndex, materialParams ) {

		const parser = this.parser;
		const materialDef = parser.json.materials[ materialIndex ];

		if ( ! materialDef.extensions || ! materialDef.extensions[ this.name ] ) {

			return Promise.resolve();

		}

		const pending = [];

		const extension = materialDef.extensions[ this.name ];

		if ( extension.transmissionFactor !== undefined ) {

			materialParams.transmission = extension.transmissionFactor;

		}

		if ( extension.transmissionTexture !== undefined ) {

			pending.push( parser.assignTexture( materialParams, 'transmissionMap', extension.transmissionTexture ) );

		}

		return Promise.all( pending );

	}

}

/**
 * Materials Volume Extension
 *
 * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_materials_volume
 */
class GLTFMaterialsVolumeExtension {

	constructor( parser ) {

		this.parser = parser;
		this.name = EXTENSIONS.KHR_MATERIALS_VOLUME;

	}

	getMaterialType( materialIndex ) {

		const parser = this.parser;
		const materialDef = parser.json.materials[ materialIndex ];

		if ( ! materialDef.extensions || ! materialDef.extensions[ this.name ] ) return null;

		return MeshPhysicalMaterial;

	}

	extendMaterialParams( materialIndex, materialParams ) {

		const parser = this.parser;
		const materialDef = parser.json.materials[ materialIndex ];

		if ( ! materialDef.extensions || ! materialDef.extensions[ this.name ] ) {

			return Promise.resolve();

		}

		const pending = [];

		const extension = materialDef.extensions[ this.name ];

		materialParams.thickness = extension.thicknessFactor !== undefined ? extension.thicknessFactor : 0;

		if ( extension.thicknessTexture !== undefined ) {

			pending.push( parser.assignTexture( materialParams, 'thicknessMap', extension.thicknessTexture ) );

		}

		materialParams.attenuationDistance = extension.attenuationDistance || 0;

		const colorArray = extension.attenuationColor || [ 1, 1, 1 ];
		materialParams.attenuationColor = new Color( colorArray[ 0 ], colorArray[ 1 ], colorArray[ 2 ] );

		return Promise.all( pending );

	}

}

/**
 * Materials ior Extension
 *
 * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_materials_ior
 */
class GLTFMaterialsIorExtension {

	constructor( parser ) {

		this.parser = parser;
		this.name = EXTENSIONS.KHR_MATERIALS_IOR;

	}

	getMaterialType( materialIndex ) {

		const parser = this.parser;
		const materialDef = parser.json.materials[ materialIndex ];

		if ( ! materialDef.extensions || ! materialDef.extensions[ this.name ] ) return null;

		return MeshPhysicalMaterial;

	}

	extendMaterialParams( materialIndex, materialParams ) {

		const parser = this.parser;
		const materialDef = parser.json.materials[ materialIndex ];

		if ( ! materialDef.extensions || ! materialDef.extensions[ this.name ] ) {

			return Promise.resolve();

		}

		const extension = materialDef.extensions[ this.name ];

		materialParams.ior = extension.ior !== undefined ? extension.ior : 1.5;

		return Promise.resolve();

	}

}

/**
 * Materials specular Extension
 *
 * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_materials_specular
 */
class GLTFMaterialsSpecularExtension {

	constructor( parser ) {

		this.parser = parser;
		this.name = EXTENSIONS.KHR_MATERIALS_SPECULAR;

	}

	getMaterialType( materialIndex ) {

		const parser = this.parser;
		const materialDef = parser.json.materials[ materialIndex ];

		if ( ! materialDef.extensions || ! materialDef.extensions[ this.name ] ) return null;

		return MeshPhysicalMaterial;

	}

	extendMaterialParams( materialIndex, materialParams ) {

		const parser = this.parser;
		const materialDef = parser.json.materials[ materialIndex ];

		if ( ! materialDef.extensions || ! materialDef.extensions[ this.name ] ) {

			return Promise.resolve();

		}

		const pending = [];

		const extension = materialDef.extensions[ this.name ];

		materialParams.specularIntensity = extension.specularFactor !== undefined ? extension.specularFactor : 1.0;

		if ( extension.specularTexture !== undefined ) {

			pending.push( parser.assignTexture( materialParams, 'specularIntensityMap', extension.specularTexture ) );

		}

		const colorArray = extension.specularColorFactor || [ 1, 1, 1 ];
		materialParams.specularColor = new Color( colorArray[ 0 ], colorArray[ 1 ], colorArray[ 2 ] );

		if ( extension.specularColorTexture !== undefined ) {

			pending.push( parser.assignTexture( materialParams, 'specularColorMap', extension.specularColorTexture, sRGBEncoding ) );

		}

		return Promise.all( pending );

	}

}

/**
 * BasisU Texture Extension
 *
 * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_texture_basisu
 */
class GLTFTextureBasisUExtension {

	constructor( parser ) {

		this.parser = parser;
		this.name = EXTENSIONS.KHR_TEXTURE_BASISU;

	}

	loadTexture( textureIndex ) {

		const parser = this.parser;
		const json = parser.json;

		const textureDef = json.textures[ textureIndex ];

		if ( ! textureDef.extensions || ! textureDef.extensions[ this.name ] ) {

			return null;

		}

		const extension = textureDef.extensions[ this.name ];
		const loader = parser.options.ktx2Loader;

		if ( ! loader ) {

			if ( json.extensionsRequired && json.extensionsRequired.indexOf( this.name ) >= 0 ) {

				throw new Error( 'THREE.GLTFLoader: setKTX2Loader must be called before loading KTX2 textures' );

			} else {

				// Assumes that the extension is optional and that a fallback texture is present
				return null;

			}

		}

		return parser.loadTextureImage( textureIndex, extension.source, loader );

	}

}

/**
 * WebP Texture Extension
 *
 * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Vendor/EXT_texture_webp
 */
class GLTFTextureWebPExtension {

	constructor( parser ) {

		this.parser = parser;
		this.name = EXTENSIONS.EXT_TEXTURE_WEBP;
		this.isSupported = null;

	}

	loadTexture( textureIndex ) {

		const name = this.name;
		const parser = this.parser;
		const json = parser.json;

		const textureDef = json.textures[ textureIndex ];

		if ( ! textureDef.extensions || ! textureDef.extensions[ name ] ) {

			return null;

		}

		const extension = textureDef.extensions[ name ];
		const source = json.images[ extension.source ];

		let loader = parser.textureLoader;
		if ( source.uri ) {

			const handler = parser.options.manager.getHandler( source.uri );
			if ( handler !== null ) loader = handler;

		}

		return this.detectSupport().then( function ( isSupported ) {

			if ( isSupported ) return parser.loadTextureImage( textureIndex, extension.source, loader );

			if ( json.extensionsRequired && json.extensionsRequired.indexOf( name ) >= 0 ) {

				throw new Error( 'THREE.GLTFLoader: WebP required by asset but unsupported.' );

			}

			// Fall back to PNG or JPEG.
			return parser.loadTexture( textureIndex );

		} );

	}

	detectSupport() {

		if ( ! this.isSupported ) {

			this.isSupported = new Promise( function ( resolve ) {

				const image = new Image();

				// Lossy test image. Support for lossy images doesn't guarantee support for all
				// WebP images, unfortunately.
				image.src = 'data:image/webp;base64,UklGRiIAAABXRUJQVlA4IBYAAAAwAQCdASoBAAEADsD+JaQAA3AAAAAA';

				image.onload = image.onerror = function () {

					resolve( image.height === 1 );

				};

			} );

		}

		return this.isSupported;

	}

}

/**
 * meshopt BufferView Compression Extension
 *
 * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Vendor/EXT_meshopt_compression
 */
class GLTFMeshoptCompression {

	constructor( parser ) {

		this.name = EXTENSIONS.EXT_MESHOPT_COMPRESSION;
		this.parser = parser;

	}

	loadBufferView( index ) {

		const json = this.parser.json;
		const bufferView = json.bufferViews[ index ];

		if ( bufferView.extensions && bufferView.extensions[ this.name ] ) {

			const extensionDef = bufferView.extensions[ this.name ];

			const buffer = this.parser.getDependency( 'buffer', extensionDef.buffer );
			const decoder = this.parser.options.meshoptDecoder;

			if ( ! decoder || ! decoder.supported ) {

				if ( json.extensionsRequired && json.extensionsRequired.indexOf( this.name ) >= 0 ) {

					throw new Error( 'THREE.GLTFLoader: setMeshoptDecoder must be called before loading compressed files' );

				} else {

					// Assumes that the extension is optional and that fallback buffer data is present
					return null;

				}

			}

			return Promise.all( [ buffer, decoder.ready ] ).then( function ( res ) {

				const byteOffset = extensionDef.byteOffset || 0;
				const byteLength = extensionDef.byteLength || 0;

				const count = extensionDef.count;
				const stride = extensionDef.byteStride;

				const result = new ArrayBuffer( count * stride );
				const source = new Uint8Array( res[ 0 ], byteOffset, byteLength );

				decoder.decodeGltfBuffer( new Uint8Array( result ), count, stride, source, extensionDef.mode, extensionDef.filter );
				return result;

			} );

		} else {

			return null;

		}

	}

}

/* BINARY EXTENSION */
const BINARY_EXTENSION_HEADER_MAGIC = 'glTF';
const BINARY_EXTENSION_HEADER_LENGTH = 12;
const BINARY_EXTENSION_CHUNK_TYPES = { JSON: 0x4E4F534A, BIN: 0x004E4942 };

class GLTFBinaryExtension {

	constructor( data ) {

		this.name = EXTENSIONS.KHR_BINARY_GLTF;
		this.content = null;
		this.body = null;

		const headerView = new DataView( data, 0, BINARY_EXTENSION_HEADER_LENGTH );

		this.header = {
			magic: LoaderUtils.decodeText( new Uint8Array( data.slice( 0, 4 ) ) ),
			version: headerView.getUint32( 4, true ),
			length: headerView.getUint32( 8, true )
		};

		if ( this.header.magic !== BINARY_EXTENSION_HEADER_MAGIC ) {

			throw new Error( 'THREE.GLTFLoader: Unsupported glTF-Binary header.' );

		} else if ( this.header.version < 2.0 ) {

			throw new Error( 'THREE.GLTFLoader: Legacy binary file detected.' );

		}

		const chunkContentsLength = this.header.length - BINARY_EXTENSION_HEADER_LENGTH;
		const chunkView = new DataView( data, BINARY_EXTENSION_HEADER_LENGTH );
		let chunkIndex = 0;

		while ( chunkIndex < chunkContentsLength ) {

			const chunkLength = chunkView.getUint32( chunkIndex, true );
			chunkIndex += 4;

			const chunkType = chunkView.getUint32( chunkIndex, true );
			chunkIndex += 4;

			if ( chunkType === BINARY_EXTENSION_CHUNK_TYPES.JSON ) {

				const contentArray = new Uint8Array( data, BINARY_EXTENSION_HEADER_LENGTH + chunkIndex, chunkLength );
				this.content = LoaderUtils.decodeText( contentArray );

			} else if ( chunkType === BINARY_EXTENSION_CHUNK_TYPES.BIN ) {

				const byteOffset = BINARY_EXTENSION_HEADER_LENGTH + chunkIndex;
				this.body = data.slice( byteOffset, byteOffset + chunkLength );

			}

			// Clients must ignore chunks with unknown types.

			chunkIndex += chunkLength;

		}

		if ( this.content === null ) {

			throw new Error( 'THREE.GLTFLoader: JSON content not found.' );

		}

	}

}

/**
 * DRACO Mesh Compression Extension
 *
 * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_draco_mesh_compression
 */
class GLTFDracoMeshCompressionExtension {

	constructor( json, dracoLoader ) {

		if ( ! dracoLoader ) {

			throw new Error( 'THREE.GLTFLoader: No DRACOLoader instance provided.' );

		}

		this.name = EXTENSIONS.KHR_DRACO_MESH_COMPRESSION;
		this.json = json;
		this.dracoLoader = dracoLoader;
		this.dracoLoader.preload();

	}

	decodePrimitive( primitive, parser ) {

		const json = this.json;
		const dracoLoader = this.dracoLoader;
		const bufferViewIndex = primitive.extensions[ this.name ].bufferView;
		const gltfAttributeMap = primitive.extensions[ this.name ].attributes;
		const threeAttributeMap = {};
		const attributeNormalizedMap = {};
		const attributeTypeMap = {};

		for ( const attributeName in gltfAttributeMap ) {

			const threeAttributeName = ATTRIBUTES[ attributeName ] || attributeName.toLowerCase();

			threeAttributeMap[ threeAttributeName ] = gltfAttributeMap[ attributeName ];

		}

		for ( const attributeName in primitive.attributes ) {

			const threeAttributeName = ATTRIBUTES[ attributeName ] || attributeName.toLowerCase();

			if ( gltfAttributeMap[ attributeName ] !== undefined ) {

				const accessorDef = json.accessors[ primitive.attributes[ attributeName ] ];
				const componentType = WEBGL_COMPONENT_TYPES[ accessorDef.componentType ];

				attributeTypeMap[ threeAttributeName ] = componentType;
				attributeNormalizedMap[ threeAttributeName ] = accessorDef.normalized === true;

			}

		}

		return parser.getDependency( 'bufferView', bufferViewIndex ).then( function ( bufferView ) {

			return new Promise( function ( resolve ) {

				dracoLoader.decodeDracoFile( bufferView, function ( geometry ) {

					for ( const attributeName in geometry.attributes ) {

						const attribute = geometry.attributes[ attributeName ];
						const normalized = attributeNormalizedMap[ attributeName ];

						if ( normalized !== undefined ) attribute.normalized = normalized;

					}

					resolve( geometry );

				}, threeAttributeMap, attributeTypeMap );

			} );

		} );

	}

}

/**
 * Texture Transform Extension
 *
 * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_texture_transform
 */
class GLTFTextureTransformExtension {

	constructor() {

		this.name = EXTENSIONS.KHR_TEXTURE_TRANSFORM;

	}

	extendTexture( texture, transform ) {

		if ( transform.texCoord !== undefined ) {

			console.warn( 'THREE.GLTFLoader: Custom UV sets in "' + this.name + '" extension not yet supported.' );

		}

		if ( transform.offset === undefined && transform.rotation === undefined && transform.scale === undefined ) {

			// See https://github.com/mrdoob/three.js/issues/21819.
			return texture;

		}

		texture = texture.clone();

		if ( transform.offset !== undefined ) {

			texture.offset.fromArray( transform.offset );

		}

		if ( transform.rotation !== undefined ) {

			texture.rotation = transform.rotation;

		}

		if ( transform.scale !== undefined ) {

			texture.repeat.fromArray( transform.scale );

		}

		texture.needsUpdate = true;

		return texture;

	}

}

/**
 * Specular-Glossiness Extension
 *
 * Specification: https://github.com/KhronosGroup/glTF/tree/main/extensions/2.0/Archived/KHR_materials_pbrSpecularGlossiness
 */

/**
 * A sub class of StandardMaterial with some of the functionality
 * changed via the `onBeforeCompile` callback
 * @pailhead
 */
class GLTFMeshStandardSGMaterial extends MeshStandardMaterial {

	constructor( params ) {

		super();

		this.isGLTFSpecularGlossinessMaterial = true;

		//various chunks that need replacing
		const specularMapParsFragmentChunk = [
			'#ifdef USE_SPECULARMAP',
			'	uniform sampler2D specularMap;',
			'#endif'
		].join( '\n' );

		const glossinessMapParsFragmentChunk = [
			'#ifdef USE_GLOSSINESSMAP',
			'	uniform sampler2D glossinessMap;',
			'#endif'
		].join( '\n' );

		const specularMapFragmentChunk = [
			'vec3 specularFactor = specular;',
			'#ifdef USE_SPECULARMAP',
			'	vec4 texelSpecular = texture2D( specularMap, vUv );',
			'	// reads channel RGB, compatible with a glTF Specular-Glossiness (RGBA) texture',
			'	specularFactor *= texelSpecular.rgb;',
			'#endif'
		].join( '\n' );

		const glossinessMapFragmentChunk = [
			'float glossinessFactor = glossiness;',
			'#ifdef USE_GLOSSINESSMAP',
			'	vec4 texelGlossiness = texture2D( glossinessMap, vUv );',
			'	// reads channel A, compatible with a glTF Specular-Glossiness (RGBA) texture',
			'	glossinessFactor *= texelGlossiness.a;',
			'#endif'
		].join( '\n' );

		const lightPhysicalFragmentChunk = [
			'PhysicalMaterial material;',
			'material.diffuseColor = diffuseColor.rgb * ( 1. - max( specularFactor.r, max( specularFactor.g, specularFactor.b ) ) );',
			'vec3 dxy = max( abs( dFdx( geometryNormal ) ), abs( dFdy( geometryNormal ) ) );',
			'float geometryRoughness = max( max( dxy.x, dxy.y ), dxy.z );',
			'material.roughness = max( 1.0 - glossinessFactor, 0.0525 ); // 0.0525 corresponds to the base mip of a 256 cubemap.',
			'material.roughness += geometryRoughness;',
			'material.roughness = min( material.roughness, 1.0 );',
			'material.specularColor = specularFactor;',
		].join( '\n' );

		const uniforms = {
			specular: { value: new Color().setHex( 0xffffff ) },
			glossiness: { value: 1 },
			specularMap: { value: null },
			glossinessMap: { value: null }
		};

		this._extraUniforms = uniforms;

		this.onBeforeCompile = function ( shader ) {

			for ( const uniformName in uniforms ) {

				shader.uniforms[ uniformName ] = uniforms[ uniformName ];

			}

			shader.fragmentShader = shader.fragmentShader
				.replace( 'uniform float roughness;', 'uniform vec3 specular;' )
				.replace( 'uniform float metalness;', 'uniform float glossiness;' )
				.replace( '#include <roughnessmap_pars_fragment>', specularMapParsFragmentChunk )
				.replace( '#include <metalnessmap_pars_fragment>', glossinessMapParsFragmentChunk )
				.replace( '#include <roughnessmap_fragment>', specularMapFragmentChunk )
				.replace( '#include <metalnessmap_fragment>', glossinessMapFragmentChunk )
				.replace( '#include <lights_physical_fragment>', lightPhysicalFragmentChunk );

		};

		Object.defineProperties( this, {

			specular: {
				get: function () {

					return uniforms.specular.value;

				},
				set: function ( v ) {

					uniforms.specular.value = v;

				}
			},

			specularMap: {
				get: function () {

					return uniforms.specularMap.value;

				},
				set: function ( v ) {

					uniforms.specularMap.value = v;

					if ( v ) {

						this.defines.USE_SPECULARMAP = ''; // USE_UV is set by the renderer for specular maps

					} else {

						delete this.defines.USE_SPECULARMAP;

					}

				}
			},

			glossiness: {
				get: function () {

					return uniforms.glossiness.value;

				},
				set: function ( v ) {

					uniforms.glossiness.value = v;

				}
			},

			glossinessMap: {
				get: function () {

					return uniforms.glossinessMap.value;

				},
				set: function ( v ) {

					uniforms.glossinessMap.value = v;

					if ( v ) {

						this.defines.USE_GLOSSINESSMAP = '';
						this.defines.USE_UV = '';

					} else {

						delete this.defines.USE_GLOSSINESSMAP;
						delete this.defines.USE_UV;

					}

				}
			}

		} );

		delete this.metalness;
		delete this.roughness;
		delete this.metalnessMap;
		delete this.roughnessMap;

		this.setValues( params );

	}

	copy( source ) {

		super.copy( source );

		this.specularMap = source.specularMap;
		this.specular.copy( source.specular );
		this.glossinessMap = source.glossinessMap;
		this.glossiness = source.glossiness;
		delete this.metalness;
		delete this.roughness;
		delete this.metalnessMap;
		delete this.roughnessMap;
		return this;

	}

}


class GLTFMaterialsPbrSpecularGlossinessExtension {

	constructor() {

		this.name = EXTENSIONS.KHR_MATERIALS_PBR_SPECULAR_GLOSSINESS;

		this.specularGlossinessParams = [
			'color',
			'map',
			'lightMap',
			'lightMapIntensity',
			'aoMap',
			'aoMapIntensity',
			'emissive',
			'emissiveIntensity',
			'emissiveMap',
			'bumpMap',
			'bumpScale',
			'normalMap',
			'normalMapType',
			'displacementMap',
			'displacementScale',
			'displacementBias',
			'specularMap',
			'specular',
			'glossinessMap',
			'glossiness',
			'alphaMap',
			'envMap',
			'envMapIntensity'
		];

	}

	getMaterialType() {

		return GLTFMeshStandardSGMaterial;

	}

	extendParams( materialParams, materialDef, parser ) {

		const pbrSpecularGlossiness = materialDef.extensions[ this.name ];

		materialParams.color = new Color( 1.0, 1.0, 1.0 );
		materialParams.opacity = 1.0;

		const pending = [];

		if ( Array.isArray( pbrSpecularGlossiness.diffuseFactor ) ) {

			const array = pbrSpecularGlossiness.diffuseFactor;

			materialParams.color.fromArray( array );
			materialParams.opacity = array[ 3 ];

		}

		if ( pbrSpecularGlossiness.diffuseTexture !== undefined ) {

			pending.push( parser.assignTexture( materialParams, 'map', pbrSpecularGlossiness.diffuseTexture, sRGBEncoding ) );

		}

		materialParams.emissive = new Color( 0.0, 0.0, 0.0 );
		materialParams.glossiness = pbrSpecularGlossiness.glossinessFactor !== undefined ? pbrSpecularGlossiness.glossinessFactor : 1.0;
		materialParams.specular = new Color( 1.0, 1.0, 1.0 );

		if ( Array.isArray( pbrSpecularGlossiness.specularFactor ) ) {

			materialParams.specular.fromArray( pbrSpecularGlossiness.specularFactor );

		}

		if ( pbrSpecularGlossiness.specularGlossinessTexture !== undefined ) {

			const specGlossMapDef = pbrSpecularGlossiness.specularGlossinessTexture;
			pending.push( parser.assignTexture( materialParams, 'glossinessMap', specGlossMapDef ) );
			pending.push( parser.assignTexture( materialParams, 'specularMap', specGlossMapDef, sRGBEncoding ) );

		}

		return Promise.all( pending );

	}

	createMaterial( materialParams ) {

		const material = new GLTFMeshStandardSGMaterial( materialParams );
		material.fog = true;

		material.color = materialParams.color;

		material.map = materialParams.map === undefined ? null : materialParams.map;

		material.lightMap = null;
		material.lightMapIntensity = 1.0;

		material.aoMap = materialParams.aoMap === undefined ? null : materialParams.aoMap;
		material.aoMapIntensity = 1.0;

		material.emissive = materialParams.emissive;
		material.emissiveIntensity = materialParams.emissiveIntensity === undefined ? 1.0 : materialParams.emissiveIntensity;
		material.emissiveMap = materialParams.emissiveMap === undefined ? null : materialParams.emissiveMap;

		material.bumpMap = materialParams.bumpMap === undefined ? null : materialParams.bumpMap;
		material.bumpScale = 1;

		material.normalMap = materialParams.normalMap === undefined ? null : materialParams.normalMap;
		material.normalMapType = TangentSpaceNormalMap;

		if ( materialParams.normalScale ) material.normalScale = materialParams.normalScale;

		material.displacementMap = null;
		material.displacementScale = 1;
		material.displacementBias = 0;

		material.specularMap = materialParams.specularMap === undefined ? null : materialParams.specularMap;
		material.specular = materialParams.specular;

		material.glossinessMap = materialParams.glossinessMap === undefined ? null : materialParams.glossinessMap;
		material.glossiness = materialParams.glossiness;

		material.alphaMap = null;

		material.envMap = materialParams.envMap === undefined ? null : materialParams.envMap;
		material.envMapIntensity = 1.0;

		return material;

	}

}

/**
 * Mesh Quantization Extension
 *
 * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_mesh_quantization
 */
class GLTFMeshQuantizationExtension {

	constructor() {

		this.name = EXTENSIONS.KHR_MESH_QUANTIZATION;

	}

}

/*********************************/
/********** INTERPOLATION ********/
/*********************************/

// Spline Interpolation
// Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#appendix-c-spline-interpolation
class GLTFCubicSplineInterpolant extends Interpolant {

	constructor( parameterPositions, sampleValues, sampleSize, resultBuffer ) {

		super( parameterPositions, sampleValues, sampleSize, resultBuffer );

	}

	copySampleValue_( index ) {

		// Copies a sample value to the result buffer. See description of glTF
		// CUBICSPLINE values layout in interpolate_() function below.

		const result = this.resultBuffer,
			values = this.sampleValues,
			valueSize = this.valueSize,
			offset = index * valueSize * 3 + valueSize;

		for ( let i = 0; i !== valueSize; i ++ ) {

			result[ i ] = values[ offset + i ];

		}

		return result;

	}

	interpolate_( i1, t0, t, t1 ) {

		const result = this.resultBuffer;
		const values = this.sampleValues;
		const stride = this.valueSize;

		const stride2 = stride * 2;
		const stride3 = stride * 3;

		const td = t1 - t0;

		const p = ( t - t0 ) / td;
		const pp = p * p;
		const ppp = pp * p;

		const offset1 = i1 * stride3;
		const offset0 = offset1 - stride3;

		const s2 = - 2 * ppp + 3 * pp;
		const s3 = ppp - pp;
		const s0 = 1 - s2;
		const s1 = s3 - pp + p;

		// Layout of keyframe output values for CUBICSPLINE animations:
		//   [ inTangent_1, splineVertex_1, outTangent_1, inTangent_2, splineVertex_2, ... ]
		for ( let i = 0; i !== stride; i ++ ) {

			const p0 = values[ offset0 + i + stride ]; // splineVertex_k
			const m0 = values[ offset0 + i + stride2 ] * td; // outTangent_k * (t_k+1 - t_k)
			const p1 = values[ offset1 + i + stride ]; // splineVertex_k+1
			const m1 = values[ offset1 + i ] * td; // inTangent_k+1 * (t_k+1 - t_k)

			result[ i ] = s0 * p0 + s1 * m0 + s2 * p1 + s3 * m1;

		}

		return result;

	}

}

const _q = new Quaternion();

class GLTFCubicSplineQuaternionInterpolant extends GLTFCubicSplineInterpolant {

	interpolate_( i1, t0, t, t1 ) {

		const result = super.interpolate_( i1, t0, t, t1 );

		_q.fromArray( result ).normalize().toArray( result );

		return result;

	}

}


/*********************************/
/********** INTERNALS ************/
/*********************************/

/* CONSTANTS */

const WEBGL_CONSTANTS = {
	FLOAT: 5126,
	//FLOAT_MAT2: 35674,
	FLOAT_MAT3: 35675,
	FLOAT_MAT4: 35676,
	FLOAT_VEC2: 35664,
	FLOAT_VEC3: 35665,
	FLOAT_VEC4: 35666,
	LINEAR: 9729,
	REPEAT: 10497,
	SAMPLER_2D: 35678,
	POINTS: 0,
	LINES: 1,
	LINE_LOOP: 2,
	LINE_STRIP: 3,
	TRIANGLES: 4,
	TRIANGLE_STRIP: 5,
	TRIANGLE_FAN: 6,
	UNSIGNED_BYTE: 5121,
	UNSIGNED_SHORT: 5123
};

const WEBGL_COMPONENT_TYPES = {
	5120: Int8Array,
	5121: Uint8Array,
	5122: Int16Array,
	5123: Uint16Array,
	5125: Uint32Array,
	5126: Float32Array
};

const WEBGL_FILTERS = {
	9728: NearestFilter,
	9729: LinearFilter,
	9984: NearestMipmapNearestFilter,
	9985: LinearMipmapNearestFilter,
	9986: NearestMipmapLinearFilter,
	9987: LinearMipmapLinearFilter
};

const WEBGL_WRAPPINGS = {
	33071: ClampToEdgeWrapping,
	33648: MirroredRepeatWrapping,
	10497: RepeatWrapping
};

const WEBGL_TYPE_SIZES = {
	'SCALAR': 1,
	'VEC2': 2,
	'VEC3': 3,
	'VEC4': 4,
	'MAT2': 4,
	'MAT3': 9,
	'MAT4': 16
};

const ATTRIBUTES = {
	POSITION: 'position',
	NORMAL: 'normal',
	TANGENT: 'tangent',
	TEXCOORD_0: 'uv',
	TEXCOORD_1: 'uv2',
	COLOR_0: 'color',
	WEIGHTS_0: 'skinWeight',
	JOINTS_0: 'skinIndex',
};

const PATH_PROPERTIES = {
	scale: 'scale',
	translation: 'position',
	rotation: 'quaternion',
	weights: 'morphTargetInfluences'
};

const INTERPOLATION = {
	CUBICSPLINE: undefined, // We use a custom interpolant (GLTFCubicSplineInterpolation) for CUBICSPLINE tracks. Each
		                        // keyframe track will be initialized with a default interpolation type, then modified.
	LINEAR: InterpolateLinear,
	STEP: InterpolateDiscrete
};

const ALPHA_MODES = {
	OPAQUE: 'OPAQUE',
	MASK: 'MASK',
	BLEND: 'BLEND'
};

/**
 * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#default-material
 */
function createDefaultMaterial( cache ) {

	if ( cache[ 'DefaultMaterial' ] === undefined ) {

		cache[ 'DefaultMaterial' ] = new MeshStandardMaterial( {
			color: 0xFFFFFF,
			emissive: 0x000000,
			metalness: 1,
			roughness: 1,
			transparent: false,
			depthTest: true,
			side: FrontSide
		} );

	}

	return cache[ 'DefaultMaterial' ];

}

function addUnknownExtensionsToUserData( knownExtensions, object, objectDef ) {

	// Add unknown glTF extensions to an object's userData.

	for ( const name in objectDef.extensions ) {

		if ( knownExtensions[ name ] === undefined ) {

			object.userData.gltfExtensions = object.userData.gltfExtensions || {};
			object.userData.gltfExtensions[ name ] = objectDef.extensions[ name ];

		}

	}

}

/**
 * @param {Object3D|Material|BufferGeometry} object
 * @param {GLTF.definition} gltfDef
 */
function assignExtrasToUserData( object, gltfDef ) {

	if ( gltfDef.extras !== undefined ) {

		if ( typeof gltfDef.extras === 'object' ) {

			Object.assign( object.userData, gltfDef.extras );

		} else {

			console.warn( 'THREE.GLTFLoader: Ignoring primitive type .extras, ' + gltfDef.extras );

		}

	}

}

/**
 * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#morph-targets
 *
 * @param {BufferGeometry} geometry
 * @param {Array<GLTF.Target>} targets
 * @param {GLTFParser} parser
 * @return {Promise<BufferGeometry>}
 */
function addMorphTargets( geometry, targets, parser ) {

	let hasMorphPosition = false;
	let hasMorphNormal = false;
	let hasMorphColor = false;

	for ( let i = 0, il = targets.length; i < il; i ++ ) {

		const target = targets[ i ];

		if ( target.POSITION !== undefined ) hasMorphPosition = true;
		if ( target.NORMAL !== undefined ) hasMorphNormal = true;
		if ( target.COLOR_0 !== undefined ) hasMorphColor = true;

		if ( hasMorphPosition && hasMorphNormal && hasMorphColor ) break;

	}

	if ( ! hasMorphPosition && ! hasMorphNormal && ! hasMorphColor ) return Promise.resolve( geometry );

	const pendingPositionAccessors = [];
	const pendingNormalAccessors = [];
	const pendingColorAccessors = [];

	for ( let i = 0, il = targets.length; i < il; i ++ ) {

		const target = targets[ i ];

		if ( hasMorphPosition ) {

			const pendingAccessor = target.POSITION !== undefined
				? parser.getDependency( 'accessor', target.POSITION )
				: geometry.attributes.position;

			pendingPositionAccessors.push( pendingAccessor );

		}

		if ( hasMorphNormal ) {

			const pendingAccessor = target.NORMAL !== undefined
				? parser.getDependency( 'accessor', target.NORMAL )
				: geometry.attributes.normal;

			pendingNormalAccessors.push( pendingAccessor );

		}

		if ( hasMorphColor ) {

			const pendingAccessor = target.COLOR_0 !== undefined
				? parser.getDependency( 'accessor', target.COLOR_0 )
				: geometry.attributes.color;

			pendingColorAccessors.push( pendingAccessor );

		}

	}

	return Promise.all( [
		Promise.all( pendingPositionAccessors ),
		Promise.all( pendingNormalAccessors ),
		Promise.all( pendingColorAccessors )
	] ).then( function ( accessors ) {

		const morphPositions = accessors[ 0 ];
		const morphNormals = accessors[ 1 ];
		const morphColors = accessors[ 2 ];

		if ( hasMorphPosition ) geometry.morphAttributes.position = morphPositions;
		if ( hasMorphNormal ) geometry.morphAttributes.normal = morphNormals;
		if ( hasMorphColor ) geometry.morphAttributes.color = morphColors;
		geometry.morphTargetsRelative = true;

		return geometry;

	} );

}

/**
 * @param {Mesh} mesh
 * @param {GLTF.Mesh} meshDef
 */
function updateMorphTargets( mesh, meshDef ) {

	mesh.updateMorphTargets();

	if ( meshDef.weights !== undefined ) {

		for ( let i = 0, il = meshDef.weights.length; i < il; i ++ ) {

			mesh.morphTargetInfluences[ i ] = meshDef.weights[ i ];

		}

	}

	// .extras has user-defined data, so check that .extras.targetNames is an array.
	if ( meshDef.extras && Array.isArray( meshDef.extras.targetNames ) ) {

		const targetNames = meshDef.extras.targetNames;

		if ( mesh.morphTargetInfluences.length === targetNames.length ) {

			mesh.morphTargetDictionary = {};

			for ( let i = 0, il = targetNames.length; i < il; i ++ ) {

				mesh.morphTargetDictionary[ targetNames[ i ] ] = i;

			}

		} else {

			console.warn( 'THREE.GLTFLoader: Invalid extras.targetNames length. Ignoring names.' );

		}

	}

}

function createPrimitiveKey( primitiveDef ) {

	const dracoExtension = primitiveDef.extensions && primitiveDef.extensions[ EXTENSIONS.KHR_DRACO_MESH_COMPRESSION ];
	let geometryKey;

	if ( dracoExtension ) {

		geometryKey = 'draco:' + dracoExtension.bufferView
				+ ':' + dracoExtension.indices
				+ ':' + createAttributesKey( dracoExtension.attributes );

	} else {

		geometryKey = primitiveDef.indices + ':' + createAttributesKey( primitiveDef.attributes ) + ':' + primitiveDef.mode;

	}

	return geometryKey;

}

function createAttributesKey( attributes ) {

	let attributesKey = '';

	const keys = Object.keys( attributes ).sort();

	for ( let i = 0, il = keys.length; i < il; i ++ ) {

		attributesKey += keys[ i ] + ':' + attributes[ keys[ i ] ] + ';';

	}

	return attributesKey;

}

function getNormalizedComponentScale( constructor ) {

	// Reference:
	// https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_mesh_quantization#encoding-quantized-data

	switch ( constructor ) {

		case Int8Array:
			return 1 / 127;

		case Uint8Array:
			return 1 / 255;

		case Int16Array:
			return 1 / 32767;

		case Uint16Array:
			return 1 / 65535;

		default:
			throw new Error( 'THREE.GLTFLoader: Unsupported normalized accessor component type.' );

	}

}

function getImageURIMimeType( uri ) {

	if ( uri.search( /\.jpe?g($|\?)/i ) > 0 || uri.search( /^data\:image\/jpeg/ ) === 0 ) return 'image/jpeg';
	if ( uri.search( /\.webp($|\?)/i ) > 0 || uri.search( /^data\:image\/webp/ ) === 0 ) return 'image/webp';

	return 'image/png';

}

/* GLTF PARSER */

class GLTFParser {

	constructor( json = {}, options = {} ) {

		this.json = json;
		this.extensions = {};
		this.plugins = {};
		this.options = options;

		// loader object cache
		this.cache = new GLTFRegistry();

		// associations between Three.js objects and glTF elements
		this.associations = new Map();

		// BufferGeometry caching
		this.primitiveCache = {};

		// Object3D instance caches
		this.meshCache = { refs: {}, uses: {} };
		this.cameraCache = { refs: {}, uses: {} };
		this.lightCache = { refs: {}, uses: {} };

		this.sourceCache = {};
		this.textureCache = {};

		// Track node names, to ensure no duplicates
		this.nodeNamesUsed = {};

		// Use an ImageBitmapLoader if imageBitmaps are supported. Moves much of the
		// expensive work of uploading a texture to the GPU off the main thread.

		const isSafari = /^((?!chrome|android).)*safari/i.test( navigator.userAgent ) === true;
		const isFirefox = navigator.userAgent.indexOf( 'Firefox' ) > - 1;
		const firefoxVersion = isFirefox ? navigator.userAgent.match( /Firefox\/([0-9]+)\./ )[ 1 ] : - 1;

		if ( typeof createImageBitmap === 'undefined' || isSafari || ( isFirefox && firefoxVersion < 98 ) ) {

			this.textureLoader = new TextureLoader( this.options.manager );

		} else {

			this.textureLoader = new ImageBitmapLoader( this.options.manager );

		}

		this.textureLoader.setCrossOrigin( this.options.crossOrigin );
		this.textureLoader.setRequestHeader( this.options.requestHeader );

		this.fileLoader = new FileLoader( this.options.manager );
		this.fileLoader.setResponseType( 'arraybuffer' );

		if ( this.options.crossOrigin === 'use-credentials' ) {

			this.fileLoader.setWithCredentials( true );

		}

	}

	setExtensions( extensions ) {

		this.extensions = extensions;

	}

	setPlugins( plugins ) {

		this.plugins = plugins;

	}

	parse( onLoad, onError ) {

		const parser = this;
		const json = this.json;
		const extensions = this.extensions;

		// Clear the loader cache
		this.cache.removeAll();

		// Mark the special nodes/meshes in json for efficient parse
		this._invokeAll( function ( ext ) {

			return ext._markDefs && ext._markDefs();

		} );

		Promise.all( this._invokeAll( function ( ext ) {

			return ext.beforeRoot && ext.beforeRoot();

		} ) ).then( function () {

			return Promise.all( [

				parser.getDependencies( 'scene' ),
				parser.getDependencies( 'animation' ),
				parser.getDependencies( 'camera' ),

			] );

		} ).then( function ( dependencies ) {

			const result = {
				scene: dependencies[ 0 ][ json.scene || 0 ],
				scenes: dependencies[ 0 ],
				animations: dependencies[ 1 ],
				cameras: dependencies[ 2 ],
				asset: json.asset,
				parser: parser,
				userData: {}
			};

			addUnknownExtensionsToUserData( extensions, result, json );

			assignExtrasToUserData( result, json );

			Promise.all( parser._invokeAll( function ( ext ) {

				return ext.afterRoot && ext.afterRoot( result );

			} ) ).then( function () {

				onLoad( result );

			} );

		} ).catch( onError );

	}

	/**
	 * Marks the special nodes/meshes in json for efficient parse.
	 */
	_markDefs() {

		const nodeDefs = this.json.nodes || [];
		const skinDefs = this.json.skins || [];
		const meshDefs = this.json.meshes || [];

		// Nothing in the node definition indicates whether it is a Bone or an
		// Object3D. Use the skins' joint references to mark bones.
		for ( let skinIndex = 0, skinLength = skinDefs.length; skinIndex < skinLength; skinIndex ++ ) {

			const joints = skinDefs[ skinIndex ].joints;

			for ( let i = 0, il = joints.length; i < il; i ++ ) {

				nodeDefs[ joints[ i ] ].isBone = true;

			}

		}

		// Iterate over all nodes, marking references to shared resources,
		// as well as skeleton joints.
		for ( let nodeIndex = 0, nodeLength = nodeDefs.length; nodeIndex < nodeLength; nodeIndex ++ ) {

			const nodeDef = nodeDefs[ nodeIndex ];

			if ( nodeDef.mesh !== undefined ) {

				this._addNodeRef( this.meshCache, nodeDef.mesh );

				// Nothing in the mesh definition indicates whether it is
				// a SkinnedMesh or Mesh. Use the node's mesh reference
				// to mark SkinnedMesh if node has skin.
				if ( nodeDef.skin !== undefined ) {

					meshDefs[ nodeDef.mesh ].isSkinnedMesh = true;

				}

			}

			if ( nodeDef.camera !== undefined ) {

				this._addNodeRef( this.cameraCache, nodeDef.camera );

			}

		}

	}

	/**
	 * Counts references to shared node / Object3D resources. These resources
	 * can be reused, or "instantiated", at multiple nodes in the scene
	 * hierarchy. Mesh, Camera, and Light instances are instantiated and must
	 * be marked. Non-scenegraph resources (like Materials, Geometries, and
	 * Textures) can be reused directly and are not marked here.
	 *
	 * Example: CesiumMilkTruck sample model reuses "Wheel" meshes.
	 */
	_addNodeRef( cache, index ) {

		if ( index === undefined ) return;

		if ( cache.refs[ index ] === undefined ) {

			cache.refs[ index ] = cache.uses[ index ] = 0;

		}

		cache.refs[ index ] ++;

	}

	/** Returns a reference to a shared resource, cloning it if necessary. */
	_getNodeRef( cache, index, object ) {

		if ( cache.refs[ index ] <= 1 ) return object;

		const ref = object.clone();

		// Propagates mappings to the cloned object, prevents mappings on the
		// original object from being lost.
		const updateMappings = ( original, clone ) => {

			const mappings = this.associations.get( original );
			if ( mappings != null ) {

				this.associations.set( clone, mappings );

			}

			for ( const [ i, child ] of original.children.entries() ) {

				updateMappings( child, clone.children[ i ] );

			}

		};

		updateMappings( object, ref );

		ref.name += '_instance_' + ( cache.uses[ index ] ++ );

		return ref;

	}

	_invokeOne( func ) {

		const extensions = Object.values( this.plugins );
		extensions.push( this );

		for ( let i = 0; i < extensions.length; i ++ ) {

			const result = func( extensions[ i ] );

			if ( result ) return result;

		}

		return null;

	}

	_invokeAll( func ) {

		const extensions = Object.values( this.plugins );
		extensions.unshift( this );

		const pending = [];

		for ( let i = 0; i < extensions.length; i ++ ) {

			const result = func( extensions[ i ] );

			if ( result ) pending.push( result );

		}

		return pending;

	}

	/**
	 * Requests the specified dependency asynchronously, with caching.
	 * @param {string} type
	 * @param {number} index
	 * @return {Promise<Object3D|Material|THREE.Texture|AnimationClip|ArrayBuffer|Object>}
	 */
	getDependency( type, index ) {

		const cacheKey = type + ':' + index;
		let dependency = this.cache.get( cacheKey );

		if ( ! dependency ) {

			switch ( type ) {

				case 'scene':
					dependency = this.loadScene( index );
					break;

				case 'node':
					dependency = this.loadNode( index );
					break;

				case 'mesh':
					dependency = this._invokeOne( function ( ext ) {

						return ext.loadMesh && ext.loadMesh( index );

					} );
					break;

				case 'accessor':
					dependency = this.loadAccessor( index );
					break;

				case 'bufferView':
					dependency = this._invokeOne( function ( ext ) {

						return ext.loadBufferView && ext.loadBufferView( index );

					} );
					break;

				case 'buffer':
					dependency = this.loadBuffer( index );
					break;

				case 'material':
					dependency = this._invokeOne( function ( ext ) {

						return ext.loadMaterial && ext.loadMaterial( index );

					} );
					break;

				case 'texture':
					dependency = this._invokeOne( function ( ext ) {

						return ext.loadTexture && ext.loadTexture( index );

					} );
					break;

				case 'skin':
					dependency = this.loadSkin( index );
					break;

				case 'animation':
					dependency = this._invokeOne( function ( ext ) {

						return ext.loadAnimation && ext.loadAnimation( index );

					} );
					break;

				case 'camera':
					dependency = this.loadCamera( index );
					break;

				default:
					throw new Error( 'Unknown type: ' + type );

			}

			this.cache.add( cacheKey, dependency );

		}

		return dependency;

	}

	/**
	 * Requests all dependencies of the specified type asynchronously, with caching.
	 * @param {string} type
	 * @return {Promise<Array<Object>>}
	 */
	getDependencies( type ) {

		let dependencies = this.cache.get( type );

		if ( ! dependencies ) {

			const parser = this;
			const defs = this.json[ type + ( type === 'mesh' ? 'es' : 's' ) ] || [];

			dependencies = Promise.all( defs.map( function ( def, index ) {

				return parser.getDependency( type, index );

			} ) );

			this.cache.add( type, dependencies );

		}

		return dependencies;

	}

	/**
	 * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#buffers-and-buffer-views
	 * @param {number} bufferIndex
	 * @return {Promise<ArrayBuffer>}
	 */
	loadBuffer( bufferIndex ) {

		const bufferDef = this.json.buffers[ bufferIndex ];
		const loader = this.fileLoader;

		if ( bufferDef.type && bufferDef.type !== 'arraybuffer' ) {

			throw new Error( 'THREE.GLTFLoader: ' + bufferDef.type + ' buffer type is not supported.' );

		}

		// If present, GLB container is required to be the first buffer.
		if ( bufferDef.uri === undefined && bufferIndex === 0 ) {

			return Promise.resolve( this.extensions[ EXTENSIONS.KHR_BINARY_GLTF ].body );

		}

		const options = this.options;

		return new Promise( function ( resolve, reject ) {

			loader.load( LoaderUtils.resolveURL( bufferDef.uri, options.path ), resolve, undefined, function () {

				reject( new Error( 'THREE.GLTFLoader: Failed to load buffer "' + bufferDef.uri + '".' ) );

			} );

		} );

	}

	/**
	 * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#buffers-and-buffer-views
	 * @param {number} bufferViewIndex
	 * @return {Promise<ArrayBuffer>}
	 */
	loadBufferView( bufferViewIndex ) {

		const bufferViewDef = this.json.bufferViews[ bufferViewIndex ];

		return this.getDependency( 'buffer', bufferViewDef.buffer ).then( function ( buffer ) {

			const byteLength = bufferViewDef.byteLength || 0;
			const byteOffset = bufferViewDef.byteOffset || 0;
			return buffer.slice( byteOffset, byteOffset + byteLength );

		} );

	}

	/**
	 * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#accessors
	 * @param {number} accessorIndex
	 * @return {Promise<BufferAttribute|InterleavedBufferAttribute>}
	 */
	loadAccessor( accessorIndex ) {

		const parser = this;
		const json = this.json;

		const accessorDef = this.json.accessors[ accessorIndex ];

		if ( accessorDef.bufferView === undefined && accessorDef.sparse === undefined ) {

			// Ignore empty accessors, which may be used to declare runtime
			// information about attributes coming from another source (e.g. Draco
			// compression extension).
			return Promise.resolve( null );

		}

		const pendingBufferViews = [];

		if ( accessorDef.bufferView !== undefined ) {

			pendingBufferViews.push( this.getDependency( 'bufferView', accessorDef.bufferView ) );

		} else {

			pendingBufferViews.push( null );

		}

		if ( accessorDef.sparse !== undefined ) {

			pendingBufferViews.push( this.getDependency( 'bufferView', accessorDef.sparse.indices.bufferView ) );
			pendingBufferViews.push( this.getDependency( 'bufferView', accessorDef.sparse.values.bufferView ) );

		}

		return Promise.all( pendingBufferViews ).then( function ( bufferViews ) {

			const bufferView = bufferViews[ 0 ];

			const itemSize = WEBGL_TYPE_SIZES[ accessorDef.type ];
			const TypedArray = WEBGL_COMPONENT_TYPES[ accessorDef.componentType ];

			// For VEC3: itemSize is 3, elementBytes is 4, itemBytes is 12.
			const elementBytes = TypedArray.BYTES_PER_ELEMENT;
			const itemBytes = elementBytes * itemSize;
			const byteOffset = accessorDef.byteOffset || 0;
			const byteStride = accessorDef.bufferView !== undefined ? json.bufferViews[ accessorDef.bufferView ].byteStride : undefined;
			const normalized = accessorDef.normalized === true;
			let array, bufferAttribute;

			// The buffer is not interleaved if the stride is the item size in bytes.
			if ( byteStride && byteStride !== itemBytes ) {

				// Each "slice" of the buffer, as defined by 'count' elements of 'byteStride' bytes, gets its own InterleavedBuffer
				// This makes sure that IBA.count reflects accessor.count properly
				const ibSlice = Math.floor( byteOffset / byteStride );
				const ibCacheKey = 'InterleavedBuffer:' + accessorDef.bufferView + ':' + accessorDef.componentType + ':' + ibSlice + ':' + accessorDef.count;
				let ib = parser.cache.get( ibCacheKey );

				if ( ! ib ) {

					array = new TypedArray( bufferView, ibSlice * byteStride, accessorDef.count * byteStride / elementBytes );

					// Integer parameters to IB/IBA are in array elements, not bytes.
					ib = new InterleavedBuffer( array, byteStride / elementBytes );

					parser.cache.add( ibCacheKey, ib );

				}

				bufferAttribute = new InterleavedBufferAttribute( ib, itemSize, ( byteOffset % byteStride ) / elementBytes, normalized );

			} else {

				if ( bufferView === null ) {

					array = new TypedArray( accessorDef.count * itemSize );

				} else {

					array = new TypedArray( bufferView, byteOffset, accessorDef.count * itemSize );

				}

				bufferAttribute = new BufferAttribute( array, itemSize, normalized );

			}

			// https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#sparse-accessors
			if ( accessorDef.sparse !== undefined ) {

				const itemSizeIndices = WEBGL_TYPE_SIZES.SCALAR;
				const TypedArrayIndices = WEBGL_COMPONENT_TYPES[ accessorDef.sparse.indices.componentType ];

				const byteOffsetIndices = accessorDef.sparse.indices.byteOffset || 0;
				const byteOffsetValues = accessorDef.sparse.values.byteOffset || 0;

				const sparseIndices = new TypedArrayIndices( bufferViews[ 1 ], byteOffsetIndices, accessorDef.sparse.count * itemSizeIndices );
				const sparseValues = new TypedArray( bufferViews[ 2 ], byteOffsetValues, accessorDef.sparse.count * itemSize );

				if ( bufferView !== null ) {

					// Avoid modifying the original ArrayBuffer, if the bufferView wasn't initialized with zeroes.
					bufferAttribute = new BufferAttribute( bufferAttribute.array.slice(), bufferAttribute.itemSize, bufferAttribute.normalized );

				}

				for ( let i = 0, il = sparseIndices.length; i < il; i ++ ) {

					const index = sparseIndices[ i ];

					bufferAttribute.setX( index, sparseValues[ i * itemSize ] );
					if ( itemSize >= 2 ) bufferAttribute.setY( index, sparseValues[ i * itemSize + 1 ] );
					if ( itemSize >= 3 ) bufferAttribute.setZ( index, sparseValues[ i * itemSize + 2 ] );
					if ( itemSize >= 4 ) bufferAttribute.setW( index, sparseValues[ i * itemSize + 3 ] );
					if ( itemSize >= 5 ) throw new Error( 'THREE.GLTFLoader: Unsupported itemSize in sparse BufferAttribute.' );

				}

			}

			return bufferAttribute;

		} );

	}

	/**
	 * Specification: https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#textures
	 * @param {number} textureIndex
	 * @return {Promise<THREE.Texture>}
	 */
	loadTexture( textureIndex ) {

		const json = this.json;
		const options = this.options;
		const textureDef = json.textures[ textureIndex ];
		const sourceIndex = textureDef.source;
		const sourceDef = json.images[ sourceIndex ];

		let loader = this.textureLoader;

		if ( sourceDef.uri ) {

			const handler = options.manager.getHandler( sourceDef.uri );
			if ( handler !== null ) loader = handler;

		}

		return this.loadTextureImage( textureIndex, sourceIndex, loader );

	}

	loadTextureImage( textureIndex, sourceIndex, loader ) {

		const parser = this;
		const json = this.json;

		const textureDef = json.textures[ textureIndex ];
		const sourceDef = json.images[ sourceIndex ];

		const cacheKey = ( sourceDef.uri || sourceDef.bufferView ) + ':' + textureDef.sampler;

		if ( this.textureCache[ cacheKey ] ) {

			// See https://github.com/mrdoob/three.js/issues/21559.
			return this.textureCache[ cacheKey ];

		}

		const promise = this.loadImageSource( sourceIndex, loader ).then( function ( texture ) {

			texture.flipY = false;

			if ( textureDef.name ) texture.name = textureDef.name;

			const samplers = json.samplers || {};
			const sampler = samplers[ textureDef.sampler ] || {};

			texture.magFilter = WEBGL_FILTERS[ sampler.magFilter ] || LinearFilter;
			texture.minFilter = WEBGL_FILTERS[ sampler.minFilter ] || LinearMipmapLinearFilter;
			texture.wrapS = WEBGL_WRAPPINGS[ sampler.wrapS ] || RepeatWrapping;
			texture.wrapT = WEBGL_WRAPPINGS[ sampler.wrapT ] || RepeatWrapping;

			parser.associations.set( texture, { textures: textureIndex } );

			return texture;

		} ).catch( function () {

			return null;

		} );

		this.textureCache[ cacheKey ] = promise;

		return promise;

	}

	loadImageSource( sourceIndex, loader ) {

		const parser = this;
		const json = this.json;
		const options = this.options;

		if ( this.sourceCache[ sourceIndex ] !== undefined ) {

			return this.sourceCache[ sourceIndex ].then( ( texture ) => texture.clone() );

		}

		const sourceDef = json.images[ sourceIndex ];

		const URL = self.URL || self.webkitURL;

		let sourceURI = sourceDef.uri || '';
		let isObjectURL = false;

		if ( sourceDef.bufferView !== undefined ) {

			// Load binary image data from bufferView, if provided.

			sourceURI = parser.getDependency( 'bufferView', sourceDef.bufferView ).then( function ( bufferView ) {

				isObjectURL = true;
				const blob = new Blob( [ bufferView ], { type: sourceDef.mimeType } );
				sourceURI = URL.createObjectURL( blob );
				return sourceURI;

			} );

		} else if ( sourceDef.uri === undefined ) {

			throw new Error( 'THREE.GLTFLoader: Image ' + sourceIndex + ' is missing URI and bufferView' );

		}

		const promise = Promise.resolve( sourceURI ).then( function ( sourceURI ) {

			return new Promise( function ( resolve, reject ) {

				let onLoad = resolve;

				if ( loader.isImageBitmapLoader === true ) {

					onLoad = function ( imageBitmap ) {

						const texture = new Texture( imageBitmap );
						texture.needsUpdate = true;

						resolve( texture );

					};

				}

				loader.load( LoaderUtils.resolveURL( sourceURI, options.path ), onLoad, undefined, reject );

			} );

		} ).then( function ( texture ) {

			// Clean up resources and configure Texture.

			if ( isObjectURL === true ) {

				URL.revokeObjectURL( sourceURI );

			}

			texture.userData.mimeType = sourceDef.mimeType || getImageURIMimeType( sourceDef.uri );

			return texture;

		} ).catch( function ( error ) {

			console.error( 'THREE.GLTFLoader: Couldn\'t load texture', sourceURI );
			throw error;

		} );

		this.sourceCache[ sourceIndex ] = promise;
		return promise;

	}

	/**
	 * Asynchronously assigns a texture to the given material parameters.
	 * @param {Object} materialParams
	 * @param {string} mapName
	 * @param {Object} mapDef
	 * @return {Promise<Texture>}
	 */
	assignTexture( materialParams, mapName, mapDef, encoding ) {

		const parser = this;

		return this.getDependency( 'texture', mapDef.index ).then( function ( texture ) {

			// Materials sample aoMap from UV set 1 and other maps from UV set 0 - this can't be configured
			// However, we will copy UV set 0 to UV set 1 on demand for aoMap
			if ( mapDef.texCoord !== undefined && mapDef.texCoord != 0 && ! ( mapName === 'aoMap' && mapDef.texCoord == 1 ) ) {

				console.warn( 'THREE.GLTFLoader: Custom UV set ' + mapDef.texCoord + ' for texture ' + mapName + ' not yet supported.' );

			}

			if ( parser.extensions[ EXTENSIONS.KHR_TEXTURE_TRANSFORM ] ) {

				const transform = mapDef.extensions !== undefined ? mapDef.extensions[ EXTENSIONS.KHR_TEXTURE_TRANSFORM ] : undefined;

				if ( transform ) {

					const gltfReference = parser.associations.get( texture );
					texture = parser.extensions[ EXTENSIONS.KHR_TEXTURE_TRANSFORM ].extendTexture( texture, transform );
					parser.associations.set( texture, gltfReference );

				}

			}

			if ( encoding !== undefined ) {

				texture.encoding = encoding;

			}

			materialParams[ mapName ] = texture;

			return texture;

		} );

	}

	/**
	 * Assigns final material to a Mesh, Line, or Points instance. The instance
	 * already has a material (generated from the glTF material options alone)
	 * but reuse of the same glTF material may require multiple threejs materials
	 * to accommodate different primitive types, defines, etc. New materials will
	 * be created if necessary, and reused from a cache.
	 * @param  {Object3D} mesh Mesh, Line, or Points instance.
	 */
	assignFinalMaterial( mesh ) {

		const geometry = mesh.geometry;
		let material = mesh.material;

		const useDerivativeTangents = geometry.attributes.tangent === undefined;
		const useVertexColors = geometry.attributes.color !== undefined;
		const useFlatShading = geometry.attributes.normal === undefined;

		if ( mesh.isPoints ) {

			const cacheKey = 'PointsMaterial:' + material.uuid;

			let pointsMaterial = this.cache.get( cacheKey );

			if ( ! pointsMaterial ) {

				pointsMaterial = new PointsMaterial();
				Material.prototype.copy.call( pointsMaterial, material );
				pointsMaterial.color.copy( material.color );
				pointsMaterial.map = material.map;
				pointsMaterial.sizeAttenuation = false; // glTF spec says points should be 1px

				this.cache.add( cacheKey, pointsMaterial );

			}

			material = pointsMaterial;

		} else if ( mesh.isLine ) {

			const cacheKey = 'LineBasicMaterial:' + material.uuid;

			let lineMaterial = this.cache.get( cacheKey );

			if ( ! lineMaterial ) {

				lineMaterial = new LineBasicMaterial();
				Material.prototype.copy.call( lineMaterial, material );
				lineMaterial.color.copy( material.color );

				this.cache.add( cacheKey, lineMaterial );

			}

			material = lineMaterial;

		}

		// Clone the material if it will be modified
		if ( useDerivativeTangents || useVertexColors || useFlatShading ) {

			let cacheKey = 'ClonedMaterial:' + material.uuid + ':';

			if ( material.isGLTFSpecularGlossinessMaterial ) cacheKey += 'specular-glossiness:';
			if ( useDerivativeTangents ) cacheKey += 'derivative-tangents:';
			if ( useVertexColors ) cacheKey += 'vertex-colors:';
			if ( useFlatShading ) cacheKey += 'flat-shading:';

			let cachedMaterial = this.cache.get( cacheKey );

			if ( ! cachedMaterial ) {

				cachedMaterial = material.clone();

				if ( useVertexColors ) cachedMaterial.vertexColors = true;
				if ( useFlatShading ) cachedMaterial.flatShading = true;

				if ( useDerivativeTangents ) {

					// https://github.com/mrdoob/three.js/issues/11438#issuecomment-507003995
					if ( cachedMaterial.normalScale ) cachedMaterial.normalScale.y *= - 1;
					if ( cachedMaterial.clearcoatNormalScale ) cachedMaterial.clearcoatNormalScale.y *= - 1;

				}

				this.cache.add( cacheKey, cachedMaterial );

				this.associations.set( cachedMaterial, this.associations.get( material ) );

			}

			material = cachedMaterial;

		}

		// workarounds for mesh and geometry

		if ( material.aoMap && geometry.attributes.uv2 === undefined && geometry.attributes.uv !== undefined ) {

			geometry.setAttribute( 'uv2', geometry.attributes.uv );

		}

		mesh.material = material;

	}

	getMaterialType( /* materialIndex */ ) {

		return MeshStandardMaterial;

	}

	/**
	 * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#materials
	 * @param {number} materialIndex
	 * @return {Promise<Material>}
	 */
	loadMaterial( materialIndex ) {

		const parser = this;
		const json = this.json;
		const extensions = this.extensions;
		const materialDef = json.materials[ materialIndex ];

		let materialType;
		const materialParams = {};
		const materialExtensions = materialDef.extensions || {};

		const pending = [];

		if ( materialExtensions[ EXTENSIONS.KHR_MATERIALS_PBR_SPECULAR_GLOSSINESS ] ) {

			const sgExtension = extensions[ EXTENSIONS.KHR_MATERIALS_PBR_SPECULAR_GLOSSINESS ];
			materialType = sgExtension.getMaterialType();
			pending.push( sgExtension.extendParams( materialParams, materialDef, parser ) );

		} else if ( materialExtensions[ EXTENSIONS.KHR_MATERIALS_UNLIT ] ) {

			const kmuExtension = extensions[ EXTENSIONS.KHR_MATERIALS_UNLIT ];
			materialType = kmuExtension.getMaterialType();
			pending.push( kmuExtension.extendParams( materialParams, materialDef, parser ) );

		} else {

			// Specification:
			// https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#metallic-roughness-material

			const metallicRoughness = materialDef.pbrMetallicRoughness || {};

			materialParams.color = new Color( 1.0, 1.0, 1.0 );
			materialParams.opacity = 1.0;

			if ( Array.isArray( metallicRoughness.baseColorFactor ) ) {

				const array = metallicRoughness.baseColorFactor;

				materialParams.color.fromArray( array );
				materialParams.opacity = array[ 3 ];

			}

			if ( metallicRoughness.baseColorTexture !== undefined ) {

				pending.push( parser.assignTexture( materialParams, 'map', metallicRoughness.baseColorTexture, sRGBEncoding ) );

			}

			materialParams.metalness = metallicRoughness.metallicFactor !== undefined ? metallicRoughness.metallicFactor : 1.0;
			materialParams.roughness = metallicRoughness.roughnessFactor !== undefined ? metallicRoughness.roughnessFactor : 1.0;

			if ( metallicRoughness.metallicRoughnessTexture !== undefined ) {

				pending.push( parser.assignTexture( materialParams, 'metalnessMap', metallicRoughness.metallicRoughnessTexture ) );
				pending.push( parser.assignTexture( materialParams, 'roughnessMap', metallicRoughness.metallicRoughnessTexture ) );

			}

			materialType = this._invokeOne( function ( ext ) {

				return ext.getMaterialType && ext.getMaterialType( materialIndex );

			} );

			pending.push( Promise.all( this._invokeAll( function ( ext ) {

				return ext.extendMaterialParams && ext.extendMaterialParams( materialIndex, materialParams );

			} ) ) );

		}

		if ( materialDef.doubleSided === true ) {

			materialParams.side = DoubleSide;

		}

		const alphaMode = materialDef.alphaMode || ALPHA_MODES.OPAQUE;

		if ( alphaMode === ALPHA_MODES.BLEND ) {

			materialParams.transparent = true;

			// See: https://github.com/mrdoob/three.js/issues/17706
			materialParams.depthWrite = false;

		} else {

			materialParams.transparent = false;

			if ( alphaMode === ALPHA_MODES.MASK ) {

				materialParams.alphaTest = materialDef.alphaCutoff !== undefined ? materialDef.alphaCutoff : 0.5;

			}

		}

		if ( materialDef.normalTexture !== undefined && materialType !== MeshBasicMaterial ) {

			pending.push( parser.assignTexture( materialParams, 'normalMap', materialDef.normalTexture ) );

			materialParams.normalScale = new Vector2( 1, 1 );

			if ( materialDef.normalTexture.scale !== undefined ) {

				const scale = materialDef.normalTexture.scale;

				materialParams.normalScale.set( scale, scale );

			}

		}

		if ( materialDef.occlusionTexture !== undefined && materialType !== MeshBasicMaterial ) {

			pending.push( parser.assignTexture( materialParams, 'aoMap', materialDef.occlusionTexture ) );

			if ( materialDef.occlusionTexture.strength !== undefined ) {

				materialParams.aoMapIntensity = materialDef.occlusionTexture.strength;

			}

		}

		if ( materialDef.emissiveFactor !== undefined && materialType !== MeshBasicMaterial ) {

			materialParams.emissive = new Color().fromArray( materialDef.emissiveFactor );

		}

		if ( materialDef.emissiveTexture !== undefined && materialType !== MeshBasicMaterial ) {

			pending.push( parser.assignTexture( materialParams, 'emissiveMap', materialDef.emissiveTexture, sRGBEncoding ) );

		}

		return Promise.all( pending ).then( function () {

			let material;

			if ( materialType === GLTFMeshStandardSGMaterial ) {

				material = extensions[ EXTENSIONS.KHR_MATERIALS_PBR_SPECULAR_GLOSSINESS ].createMaterial( materialParams );

			} else {

				material = new materialType( materialParams );

			}

			if ( materialDef.name ) material.name = materialDef.name;

			assignExtrasToUserData( material, materialDef );

			parser.associations.set( material, { materials: materialIndex } );

			if ( materialDef.extensions ) addUnknownExtensionsToUserData( extensions, material, materialDef );

			return material;

		} );

	}

	/** When Object3D instances are targeted by animation, they need unique names. */
	createUniqueName( originalName ) {

		const sanitizedName = PropertyBinding.sanitizeNodeName( originalName || '' );

		let name = sanitizedName;

		for ( let i = 1; this.nodeNamesUsed[ name ]; ++ i ) {

			name = sanitizedName + '_' + i;

		}

		this.nodeNamesUsed[ name ] = true;

		return name;

	}

	/**
	 * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#geometry
	 *
	 * Creates BufferGeometries from primitives.
	 *
	 * @param {Array<GLTF.Primitive>} primitives
	 * @return {Promise<Array<BufferGeometry>>}
	 */
	loadGeometries( primitives ) {

		const parser = this;
		const extensions = this.extensions;
		const cache = this.primitiveCache;

		function createDracoPrimitive( primitive ) {

			return extensions[ EXTENSIONS.KHR_DRACO_MESH_COMPRESSION ]
				.decodePrimitive( primitive, parser )
				.then( function ( geometry ) {

					return addPrimitiveAttributes( geometry, primitive, parser );

				} );

		}

		const pending = [];

		for ( let i = 0, il = primitives.length; i < il; i ++ ) {

			const primitive = primitives[ i ];
			const cacheKey = createPrimitiveKey( primitive );

			// See if we've already created this geometry
			const cached = cache[ cacheKey ];

			if ( cached ) {

				// Use the cached geometry if it exists
				pending.push( cached.promise );

			} else {

				let geometryPromise;

				if ( primitive.extensions && primitive.extensions[ EXTENSIONS.KHR_DRACO_MESH_COMPRESSION ] ) {

					// Use DRACO geometry if available
					geometryPromise = createDracoPrimitive( primitive );

				} else {

					// Otherwise create a new geometry
					geometryPromise = addPrimitiveAttributes( new BufferGeometry(), primitive, parser );

				}

				// Cache this geometry
				cache[ cacheKey ] = { primitive: primitive, promise: geometryPromise };

				pending.push( geometryPromise );

			}

		}

		return Promise.all( pending );

	}

	/**
	 * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#meshes
	 * @param {number} meshIndex
	 * @return {Promise<Group|Mesh|SkinnedMesh>}
	 */
	loadMesh( meshIndex ) {

		const parser = this;
		const json = this.json;
		const extensions = this.extensions;

		const meshDef = json.meshes[ meshIndex ];
		const primitives = meshDef.primitives;

		const pending = [];

		for ( let i = 0, il = primitives.length; i < il; i ++ ) {

			const material = primitives[ i ].material === undefined
				? createDefaultMaterial( this.cache )
				: this.getDependency( 'material', primitives[ i ].material );

			pending.push( material );

		}

		pending.push( parser.loadGeometries( primitives ) );

		return Promise.all( pending ).then( function ( results ) {

			const materials = results.slice( 0, results.length - 1 );
			const geometries = results[ results.length - 1 ];

			const meshes = [];

			for ( let i = 0, il = geometries.length; i < il; i ++ ) {

				const geometry = geometries[ i ];
				const primitive = primitives[ i ];

				// 1. create Mesh

				let mesh;

				const material = materials[ i ];

				if ( primitive.mode === WEBGL_CONSTANTS.TRIANGLES ||
						primitive.mode === WEBGL_CONSTANTS.TRIANGLE_STRIP ||
						primitive.mode === WEBGL_CONSTANTS.TRIANGLE_FAN ||
						primitive.mode === undefined ) {

					// .isSkinnedMesh isn't in glTF spec. See ._markDefs()
					mesh = meshDef.isSkinnedMesh === true
						? new SkinnedMesh( geometry, material )
						: new Mesh( geometry, material );

					if ( mesh.isSkinnedMesh === true && ! mesh.geometry.attributes.skinWeight.normalized ) {

						// we normalize floating point skin weight array to fix malformed assets (see #15319)
						// it's important to skip this for non-float32 data since normalizeSkinWeights assumes non-normalized inputs
						mesh.normalizeSkinWeights();

					}

					if ( primitive.mode === WEBGL_CONSTANTS.TRIANGLE_STRIP ) {

						mesh.geometry = toTrianglesDrawMode( mesh.geometry, TriangleStripDrawMode );

					} else if ( primitive.mode === WEBGL_CONSTANTS.TRIANGLE_FAN ) {

						mesh.geometry = toTrianglesDrawMode( mesh.geometry, TriangleFanDrawMode );

					}

				} else if ( primitive.mode === WEBGL_CONSTANTS.LINES ) {

					mesh = new LineSegments( geometry, material );

				} else if ( primitive.mode === WEBGL_CONSTANTS.LINE_STRIP ) {

					mesh = new Line( geometry, material );

				} else if ( primitive.mode === WEBGL_CONSTANTS.LINE_LOOP ) {

					mesh = new LineLoop( geometry, material );

				} else if ( primitive.mode === WEBGL_CONSTANTS.POINTS ) {

					mesh = new Points( geometry, material );

				} else {

					throw new Error( 'THREE.GLTFLoader: Primitive mode unsupported: ' + primitive.mode );

				}

				if ( Object.keys( mesh.geometry.morphAttributes ).length > 0 ) {

					updateMorphTargets( mesh, meshDef );

				}

				mesh.name = parser.createUniqueName( meshDef.name || ( 'mesh_' + meshIndex ) );

				assignExtrasToUserData( mesh, meshDef );

				if ( primitive.extensions ) addUnknownExtensionsToUserData( extensions, mesh, primitive );

				parser.assignFinalMaterial( mesh );

				meshes.push( mesh );

			}

			for ( let i = 0, il = meshes.length; i < il; i ++ ) {

				parser.associations.set( meshes[ i ], {
					meshes: meshIndex,
					primitives: i
				} );

			}

			if ( meshes.length === 1 ) {

				return meshes[ 0 ];

			}

			const group = new Group();

			parser.associations.set( group, { meshes: meshIndex } );

			for ( let i = 0, il = meshes.length; i < il; i ++ ) {

				group.add( meshes[ i ] );

			}

			return group;

		} );

	}

	/**
	 * Specification: https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#cameras
	 * @param {number} cameraIndex
	 * @return {Promise<THREE.Camera>}
	 */
	loadCamera( cameraIndex ) {

		let camera;
		const cameraDef = this.json.cameras[ cameraIndex ];
		const params = cameraDef[ cameraDef.type ];

		if ( ! params ) {

			console.warn( 'THREE.GLTFLoader: Missing camera parameters.' );
			return;

		}

		if ( cameraDef.type === 'perspective' ) {

			camera = new PerspectiveCamera( MathUtils.radToDeg( params.yfov ), params.aspectRatio || 1, params.znear || 1, params.zfar || 2e6 );

		} else if ( cameraDef.type === 'orthographic' ) {

			camera = new OrthographicCamera( - params.xmag, params.xmag, params.ymag, - params.ymag, params.znear, params.zfar );

		}

		if ( cameraDef.name ) camera.name = this.createUniqueName( cameraDef.name );

		assignExtrasToUserData( camera, cameraDef );

		return Promise.resolve( camera );

	}

	/**
	 * Specification: https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#skins
	 * @param {number} skinIndex
	 * @return {Promise<Object>}
	 */
	loadSkin( skinIndex ) {

		const skinDef = this.json.skins[ skinIndex ];

		const skinEntry = { joints: skinDef.joints };

		if ( skinDef.inverseBindMatrices === undefined ) {

			return Promise.resolve( skinEntry );

		}

		return this.getDependency( 'accessor', skinDef.inverseBindMatrices ).then( function ( accessor ) {

			skinEntry.inverseBindMatrices = accessor;

			return skinEntry;

		} );

	}

	/**
	 * Specification: https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#animations
	 * @param {number} animationIndex
	 * @return {Promise<AnimationClip>}
	 */
	loadAnimation( animationIndex ) {

		const json = this.json;

		const animationDef = json.animations[ animationIndex ];

		const pendingNodes = [];
		const pendingInputAccessors = [];
		const pendingOutputAccessors = [];
		const pendingSamplers = [];
		const pendingTargets = [];

		for ( let i = 0, il = animationDef.channels.length; i < il; i ++ ) {

			const channel = animationDef.channels[ i ];
			const sampler = animationDef.samplers[ channel.sampler ];
			const target = channel.target;
			const name = target.node !== undefined ? target.node : target.id; // NOTE: target.id is deprecated.
			const input = animationDef.parameters !== undefined ? animationDef.parameters[ sampler.input ] : sampler.input;
			const output = animationDef.parameters !== undefined ? animationDef.parameters[ sampler.output ] : sampler.output;

			pendingNodes.push( this.getDependency( 'node', name ) );
			pendingInputAccessors.push( this.getDependency( 'accessor', input ) );
			pendingOutputAccessors.push( this.getDependency( 'accessor', output ) );
			pendingSamplers.push( sampler );
			pendingTargets.push( target );

		}

		return Promise.all( [

			Promise.all( pendingNodes ),
			Promise.all( pendingInputAccessors ),
			Promise.all( pendingOutputAccessors ),
			Promise.all( pendingSamplers ),
			Promise.all( pendingTargets )

		] ).then( function ( dependencies ) {

			const nodes = dependencies[ 0 ];
			const inputAccessors = dependencies[ 1 ];
			const outputAccessors = dependencies[ 2 ];
			const samplers = dependencies[ 3 ];
			const targets = dependencies[ 4 ];

			const tracks = [];

			for ( let i = 0, il = nodes.length; i < il; i ++ ) {

				const node = nodes[ i ];
				const inputAccessor = inputAccessors[ i ];
				const outputAccessor = outputAccessors[ i ];
				const sampler = samplers[ i ];
				const target = targets[ i ];

				if ( node === undefined ) continue;

				node.updateMatrix();

				let TypedKeyframeTrack;

				switch ( PATH_PROPERTIES[ target.path ] ) {

					case PATH_PROPERTIES.weights:

						TypedKeyframeTrack = NumberKeyframeTrack;
						break;

					case PATH_PROPERTIES.rotation:

						TypedKeyframeTrack = QuaternionKeyframeTrack;
						break;

					case PATH_PROPERTIES.position:
					case PATH_PROPERTIES.scale:
					default:

						TypedKeyframeTrack = VectorKeyframeTrack;
						break;

				}

				const targetName = node.name ? node.name : node.uuid;

				const interpolation = sampler.interpolation !== undefined ? INTERPOLATION[ sampler.interpolation ] : InterpolateLinear;

				const targetNames = [];

				if ( PATH_PROPERTIES[ target.path ] === PATH_PROPERTIES.weights ) {

					node.traverse( function ( object ) {

						if ( object.morphTargetInfluences ) {

							targetNames.push( object.name ? object.name : object.uuid );

						}

					} );

				} else {

					targetNames.push( targetName );

				}

				let outputArray = outputAccessor.array;

				if ( outputAccessor.normalized ) {

					const scale = getNormalizedComponentScale( outputArray.constructor );
					const scaled = new Float32Array( outputArray.length );

					for ( let j = 0, jl = outputArray.length; j < jl; j ++ ) {

						scaled[ j ] = outputArray[ j ] * scale;

					}

					outputArray = scaled;

				}

				for ( let j = 0, jl = targetNames.length; j < jl; j ++ ) {

					const track = new TypedKeyframeTrack(
						targetNames[ j ] + '.' + PATH_PROPERTIES[ target.path ],
						inputAccessor.array,
						outputArray,
						interpolation
					);

					// Override interpolation with custom factory method.
					if ( sampler.interpolation === 'CUBICSPLINE' ) {

						track.createInterpolant = function InterpolantFactoryMethodGLTFCubicSpline( result ) {

							// A CUBICSPLINE keyframe in glTF has three output values for each input value,
							// representing inTangent, splineVertex, and outTangent. As a result, track.getValueSize()
							// must be divided by three to get the interpolant's sampleSize argument.

							const interpolantType = ( this instanceof QuaternionKeyframeTrack ) ? GLTFCubicSplineQuaternionInterpolant : GLTFCubicSplineInterpolant;

							return new interpolantType( this.times, this.values, this.getValueSize() / 3, result );

						};

						// Mark as CUBICSPLINE. `track.getInterpolation()` doesn't support custom interpolants.
						track.createInterpolant.isInterpolantFactoryMethodGLTFCubicSpline = true;

					}

					tracks.push( track );

				}

			}

			const name = animationDef.name ? animationDef.name : 'animation_' + animationIndex;

			return new AnimationClip( name, undefined, tracks );

		} );

	}

	createNodeMesh( nodeIndex ) {

		const json = this.json;
		const parser = this;
		const nodeDef = json.nodes[ nodeIndex ];

		if ( nodeDef.mesh === undefined ) return null;

		return parser.getDependency( 'mesh', nodeDef.mesh ).then( function ( mesh ) {

			const node = parser._getNodeRef( parser.meshCache, nodeDef.mesh, mesh );

			// if weights are provided on the node, override weights on the mesh.
			if ( nodeDef.weights !== undefined ) {

				node.traverse( function ( o ) {

					if ( ! o.isMesh ) return;

					for ( let i = 0, il = nodeDef.weights.length; i < il; i ++ ) {

						o.morphTargetInfluences[ i ] = nodeDef.weights[ i ];

					}

				} );

			}

			return node;

		} );

	}

	/**
	 * Specification: https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#nodes-and-hierarchy
	 * @param {number} nodeIndex
	 * @return {Promise<Object3D>}
	 */
	loadNode( nodeIndex ) {

		const json = this.json;
		const extensions = this.extensions;
		const parser = this;

		const nodeDef = json.nodes[ nodeIndex ];

		// reserve node's name before its dependencies, so the root has the intended name.
		const nodeName = nodeDef.name ? parser.createUniqueName( nodeDef.name ) : '';

		return ( function () {

			const pending = [];

			const meshPromise = parser._invokeOne( function ( ext ) {

				return ext.createNodeMesh && ext.createNodeMesh( nodeIndex );

			} );

			if ( meshPromise ) {

				pending.push( meshPromise );

			}

			if ( nodeDef.camera !== undefined ) {

				pending.push( parser.getDependency( 'camera', nodeDef.camera ).then( function ( camera ) {

					return parser._getNodeRef( parser.cameraCache, nodeDef.camera, camera );

				} ) );

			}

			parser._invokeAll( function ( ext ) {

				return ext.createNodeAttachment && ext.createNodeAttachment( nodeIndex );

			} ).forEach( function ( promise ) {

				pending.push( promise );

			} );

			return Promise.all( pending );

		}() ).then( function ( objects ) {

			let node;

			// .isBone isn't in glTF spec. See ._markDefs
			if ( nodeDef.isBone === true ) {

				node = new Bone();

			} else if ( objects.length > 1 ) {

				node = new Group();

			} else if ( objects.length === 1 ) {

				node = objects[ 0 ];

			} else {

				node = new Object3D();

			}

			if ( node !== objects[ 0 ] ) {

				for ( let i = 0, il = objects.length; i < il; i ++ ) {

					node.add( objects[ i ] );

				}

			}

			if ( nodeDef.name ) {

				node.userData.name = nodeDef.name;
				node.name = nodeName;

			}

			assignExtrasToUserData( node, nodeDef );

			if ( nodeDef.extensions ) addUnknownExtensionsToUserData( extensions, node, nodeDef );

			if ( nodeDef.matrix !== undefined ) {

				const matrix = new Matrix4();
				matrix.fromArray( nodeDef.matrix );
				node.applyMatrix4( matrix );

			} else {

				if ( nodeDef.translation !== undefined ) {

					node.position.fromArray( nodeDef.translation );

				}

				if ( nodeDef.rotation !== undefined ) {

					node.quaternion.fromArray( nodeDef.rotation );

				}

				if ( nodeDef.scale !== undefined ) {

					node.scale.fromArray( nodeDef.scale );

				}

			}

			if ( ! parser.associations.has( node ) ) {

				parser.associations.set( node, {} );

			}

			parser.associations.get( node ).nodes = nodeIndex;

			return node;

		} );

	}

	/**
	 * Specification: https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#scenes
	 * @param {number} sceneIndex
	 * @return {Promise<Group>}
	 */
	loadScene( sceneIndex ) {

		const json = this.json;
		const extensions = this.extensions;
		const sceneDef = this.json.scenes[ sceneIndex ];
		const parser = this;

		// Loader returns Group, not Scene.
		// See: https://github.com/mrdoob/three.js/issues/18342#issuecomment-578981172
		const scene = new Group();
		if ( sceneDef.name ) scene.name = parser.createUniqueName( sceneDef.name );

		assignExtrasToUserData( scene, sceneDef );

		if ( sceneDef.extensions ) addUnknownExtensionsToUserData( extensions, scene, sceneDef );

		const nodeIds = sceneDef.nodes || [];

		const pending = [];

		for ( let i = 0, il = nodeIds.length; i < il; i ++ ) {

			pending.push( buildNodeHierarchy( nodeIds[ i ], scene, json, parser ) );

		}

		return Promise.all( pending ).then( function () {

			// Removes dangling associations, associations that reference a node that
			// didn't make it into the scene.
			const reduceAssociations = ( node ) => {

				const reducedAssociations = new Map();

				for ( const [ key, value ] of parser.associations ) {

					if ( key instanceof Material || key instanceof Texture ) {

						reducedAssociations.set( key, value );

					}

				}

				node.traverse( ( node ) => {

					const mappings = parser.associations.get( node );

					if ( mappings != null ) {

						reducedAssociations.set( node, mappings );

					}

				} );

				return reducedAssociations;

			};

			parser.associations = reduceAssociations( scene );

			return scene;

		} );

	}

}

function buildNodeHierarchy( nodeId, parentObject, json, parser ) {

	const nodeDef = json.nodes[ nodeId ];

	return parser.getDependency( 'node', nodeId ).then( function ( node ) {

		if ( nodeDef.skin === undefined ) return node;

		// build skeleton here as well

		let skinEntry;

		return parser.getDependency( 'skin', nodeDef.skin ).then( function ( skin ) {

			skinEntry = skin;

			const pendingJoints = [];

			for ( let i = 0, il = skinEntry.joints.length; i < il; i ++ ) {

				pendingJoints.push( parser.getDependency( 'node', skinEntry.joints[ i ] ) );

			}

			return Promise.all( pendingJoints );

		} ).then( function ( jointNodes ) {

			node.traverse( function ( mesh ) {

				if ( ! mesh.isMesh ) return;

				const bones = [];
				const boneInverses = [];

				for ( let j = 0, jl = jointNodes.length; j < jl; j ++ ) {

					const jointNode = jointNodes[ j ];

					if ( jointNode ) {

						bones.push( jointNode );

						const mat = new Matrix4();

						if ( skinEntry.inverseBindMatrices !== undefined ) {

							mat.fromArray( skinEntry.inverseBindMatrices.array, j * 16 );

						}

						boneInverses.push( mat );

					} else {

						console.warn( 'THREE.GLTFLoader: Joint "%s" could not be found.', skinEntry.joints[ j ] );

					}

				}

				mesh.bind( new Skeleton( bones, boneInverses ), mesh.matrixWorld );

			} );

			return node;

		} );

	} ).then( function ( node ) {

		// build node hierachy

		parentObject.add( node );

		const pending = [];

		if ( nodeDef.children ) {

			const children = nodeDef.children;

			for ( let i = 0, il = children.length; i < il; i ++ ) {

				const child = children[ i ];
				pending.push( buildNodeHierarchy( child, node, json, parser ) );

			}

		}

		return Promise.all( pending );

	} );

}

/**
 * @param {BufferGeometry} geometry
 * @param {GLTF.Primitive} primitiveDef
 * @param {GLTFParser} parser
 */
function computeBounds( geometry, primitiveDef, parser ) {

	const attributes = primitiveDef.attributes;

	const box = new Box3();

	if ( attributes.POSITION !== undefined ) {

		const accessor = parser.json.accessors[ attributes.POSITION ];

		const min = accessor.min;
		const max = accessor.max;

		// glTF requires 'min' and 'max', but VRM (which extends glTF) currently ignores that requirement.

		if ( min !== undefined && max !== undefined ) {

			box.set(
				new Vector3( min[ 0 ], min[ 1 ], min[ 2 ] ),
				new Vector3( max[ 0 ], max[ 1 ], max[ 2 ] )
			);

			if ( accessor.normalized ) {

				const boxScale = getNormalizedComponentScale( WEBGL_COMPONENT_TYPES[ accessor.componentType ] );
				box.min.multiplyScalar( boxScale );
				box.max.multiplyScalar( boxScale );

			}

		} else {

			console.warn( 'THREE.GLTFLoader: Missing min/max properties for accessor POSITION.' );

			return;

		}

	} else {

		return;

	}

	const targets = primitiveDef.targets;

	if ( targets !== undefined ) {

		const maxDisplacement = new Vector3();
		const vector = new Vector3();

		for ( let i = 0, il = targets.length; i < il; i ++ ) {

			const target = targets[ i ];

			if ( target.POSITION !== undefined ) {

				const accessor = parser.json.accessors[ target.POSITION ];
				const min = accessor.min;
				const max = accessor.max;

				// glTF requires 'min' and 'max', but VRM (which extends glTF) currently ignores that requirement.

				if ( min !== undefined && max !== undefined ) {

					// we need to get max of absolute components because target weight is [-1,1]
					vector.setX( Math.max( Math.abs( min[ 0 ] ), Math.abs( max[ 0 ] ) ) );
					vector.setY( Math.max( Math.abs( min[ 1 ] ), Math.abs( max[ 1 ] ) ) );
					vector.setZ( Math.max( Math.abs( min[ 2 ] ), Math.abs( max[ 2 ] ) ) );


					if ( accessor.normalized ) {

						const boxScale = getNormalizedComponentScale( WEBGL_COMPONENT_TYPES[ accessor.componentType ] );
						vector.multiplyScalar( boxScale );

					}

					// Note: this assumes that the sum of all weights is at most 1. This isn't quite correct - it's more conservative
					// to assume that each target can have a max weight of 1. However, for some use cases - notably, when morph targets
					// are used to implement key-frame animations and as such only two are active at a time - this results in very large
					// boxes. So for now we make a box that's sometimes a touch too small but is hopefully mostly of reasonable size.
					maxDisplacement.max( vector );

				} else {

					console.warn( 'THREE.GLTFLoader: Missing min/max properties for accessor POSITION.' );

				}

			}

		}

		// As per comment above this box isn't conservative, but has a reasonable size for a very large number of morph targets.
		box.expandByVector( maxDisplacement );

	}

	geometry.boundingBox = box;

	const sphere = new Sphere();

	box.getCenter( sphere.center );
	sphere.radius = box.min.distanceTo( box.max ) / 2;

	geometry.boundingSphere = sphere;

}

/**
 * @param {BufferGeometry} geometry
 * @param {GLTF.Primitive} primitiveDef
 * @param {GLTFParser} parser
 * @return {Promise<BufferGeometry>}
 */
function addPrimitiveAttributes( geometry, primitiveDef, parser ) {

	const attributes = primitiveDef.attributes;

	const pending = [];

	function assignAttributeAccessor( accessorIndex, attributeName ) {

		return parser.getDependency( 'accessor', accessorIndex )
			.then( function ( accessor ) {

				geometry.setAttribute( attributeName, accessor );

			} );

	}

	for ( const gltfAttributeName in attributes ) {

		const threeAttributeName = ATTRIBUTES[ gltfAttributeName ] || gltfAttributeName.toLowerCase();

		// Skip attributes already provided by e.g. Draco extension.
		if ( threeAttributeName in geometry.attributes ) continue;

		pending.push( assignAttributeAccessor( attributes[ gltfAttributeName ], threeAttributeName ) );

	}

	if ( primitiveDef.indices !== undefined && ! geometry.index ) {

		const accessor = parser.getDependency( 'accessor', primitiveDef.indices ).then( function ( accessor ) {

			geometry.setIndex( accessor );

		} );

		pending.push( accessor );

	}

	assignExtrasToUserData( geometry, primitiveDef );

	computeBounds( geometry, primitiveDef, parser );

	return Promise.all( pending ).then( function () {

		return primitiveDef.targets !== undefined
			? addMorphTargets( geometry, primitiveDef.targets, parser )
			: geometry;

	} );

}

/**
 * @param {BufferGeometry} geometry
 * @param {Number} drawMode
 * @return {BufferGeometry}
 */
function toTrianglesDrawMode( geometry, drawMode ) {

	let index = geometry.getIndex();

	// generate index if not present

	if ( index === null ) {

		const indices = [];

		const position = geometry.getAttribute( 'position' );

		if ( position !== undefined ) {

			for ( let i = 0; i < position.count; i ++ ) {

				indices.push( i );

			}

			geometry.setIndex( indices );
			index = geometry.getIndex();

		} else {

			console.error( 'THREE.GLTFLoader.toTrianglesDrawMode(): Undefined position attribute. Processing not possible.' );
			return geometry;

		}

	}

	//

	const numberOfTriangles = index.count - 2;
	const newIndices = [];

	if ( drawMode === TriangleFanDrawMode ) {

		// gl.TRIANGLE_FAN

		for ( let i = 1; i <= numberOfTriangles; i ++ ) {

			newIndices.push( index.getX( 0 ) );
			newIndices.push( index.getX( i ) );
			newIndices.push( index.getX( i + 1 ) );

		}

	} else {

		// gl.TRIANGLE_STRIP

		for ( let i = 0; i < numberOfTriangles; i ++ ) {

			if ( i % 2 === 0 ) {

				newIndices.push( index.getX( i ) );
				newIndices.push( index.getX( i + 1 ) );
				newIndices.push( index.getX( i + 2 ) );


			} else {

				newIndices.push( index.getX( i + 2 ) );
				newIndices.push( index.getX( i + 1 ) );
				newIndices.push( index.getX( i ) );

			}

		}

	}

	if ( ( newIndices.length / 3 ) !== numberOfTriangles ) {

		console.error( 'THREE.GLTFLoader.toTrianglesDrawMode(): Unable to generate correct amount of triangles.' );

	}

	// build final geometry

	const newGeometry = geometry.clone();
	newGeometry.setIndex( newIndices );

	return newGeometry;

}

const GLTFLoaderPromise = (url, onProgress) => {
    const loader = new GLTFLoader();
    return new Promise((resolve, reject) => {
        // 📝 [Three.js gltf模型加载后是黑色的](https://zhuanlan.zhihu.com/p/350136476)
        loader.load(
        // TODO:参考 axios 的 combine url，保证路径不会出错
        url, ({ scene }) => resolve(scene), onProgress, reject);
    });
};

const warn = (msg, ...args) => {
    console.warn(`[KTMap warn] ${msg}`, ...args);
};

var global$1 = (typeof global !== "undefined" ? global :
  typeof self !== "undefined" ? self :
  typeof window !== "undefined" ? window : {});

/** Detect free variable `global` from Node.js. */
var freeGlobal = typeof global$1 == 'object' && global$1 && global$1.Object === Object && global$1;

var freeGlobal$1 = freeGlobal;

/** Detect free variable `self`. */
var freeSelf = typeof self == 'object' && self && self.Object === Object && self;

/** Used as a reference to the global object. */
var root = freeGlobal$1 || freeSelf || Function('return this')();

var root$1 = root;

/** Built-in value references. */
var Symbol = root$1.Symbol;

var Symbol$1 = Symbol;

/** Used for built-in method references. */
var objectProto$a = Object.prototype;

/** Used to check objects for own properties. */
var hasOwnProperty$8 = objectProto$a.hasOwnProperty;

/**
 * Used to resolve the
 * [`toStringTag`](http://ecma-international.org/ecma-262/7.0/#sec-object.prototype.tostring)
 * of values.
 */
var nativeObjectToString$1 = objectProto$a.toString;

/** Built-in value references. */
var symToStringTag$1 = Symbol$1 ? Symbol$1.toStringTag : undefined;

/**
 * A specialized version of `baseGetTag` which ignores `Symbol.toStringTag` values.
 *
 * @private
 * @param {*} value The value to query.
 * @returns {string} Returns the raw `toStringTag`.
 */
function getRawTag(value) {
  var isOwn = hasOwnProperty$8.call(value, symToStringTag$1),
      tag = value[symToStringTag$1];

  try {
    value[symToStringTag$1] = undefined;
    var unmasked = true;
  } catch (e) {}

  var result = nativeObjectToString$1.call(value);
  if (unmasked) {
    if (isOwn) {
      value[symToStringTag$1] = tag;
    } else {
      delete value[symToStringTag$1];
    }
  }
  return result;
}

/** Used for built-in method references. */
var objectProto$9 = Object.prototype;

/**
 * Used to resolve the
 * [`toStringTag`](http://ecma-international.org/ecma-262/7.0/#sec-object.prototype.tostring)
 * of values.
 */
var nativeObjectToString = objectProto$9.toString;

/**
 * Converts `value` to a string using `Object.prototype.toString`.
 *
 * @private
 * @param {*} value The value to convert.
 * @returns {string} Returns the converted string.
 */
function objectToString$1(value) {
  return nativeObjectToString.call(value);
}

/** `Object#toString` result references. */
var nullTag = '[object Null]',
    undefinedTag = '[object Undefined]';

/** Built-in value references. */
var symToStringTag = Symbol$1 ? Symbol$1.toStringTag : undefined;

/**
 * The base implementation of `getTag` without fallbacks for buggy environments.
 *
 * @private
 * @param {*} value The value to query.
 * @returns {string} Returns the `toStringTag`.
 */
function baseGetTag(value) {
  if (value == null) {
    return value === undefined ? undefinedTag : nullTag;
  }
  return (symToStringTag && symToStringTag in Object(value))
    ? getRawTag(value)
    : objectToString$1(value);
}

/**
 * Checks if `value` is object-like. A value is object-like if it's not `null`
 * and has a `typeof` result of "object".
 *
 * @static
 * @memberOf _
 * @since 4.0.0
 * @category Lang
 * @param {*} value The value to check.
 * @returns {boolean} Returns `true` if `value` is object-like, else `false`.
 * @example
 *
 * _.isObjectLike({});
 * // => true
 *
 * _.isObjectLike([1, 2, 3]);
 * // => true
 *
 * _.isObjectLike(_.noop);
 * // => false
 *
 * _.isObjectLike(null);
 * // => false
 */
function isObjectLike(value) {
  return value != null && typeof value == 'object';
}

/** `Object#toString` result references. */
var symbolTag = '[object Symbol]';

/**
 * Checks if `value` is classified as a `Symbol` primitive or object.
 *
 * @static
 * @memberOf _
 * @since 4.0.0
 * @category Lang
 * @param {*} value The value to check.
 * @returns {boolean} Returns `true` if `value` is a symbol, else `false`.
 * @example
 *
 * _.isSymbol(Symbol.iterator);
 * // => true
 *
 * _.isSymbol('abc');
 * // => false
 */
function isSymbol$1(value) {
  return typeof value == 'symbol' ||
    (isObjectLike(value) && baseGetTag(value) == symbolTag);
}

/**
 * Checks if `value` is classified as an `Array` object.
 *
 * @static
 * @memberOf _
 * @since 0.1.0
 * @category Lang
 * @param {*} value The value to check.
 * @returns {boolean} Returns `true` if `value` is an array, else `false`.
 * @example
 *
 * _.isArray([1, 2, 3]);
 * // => true
 *
 * _.isArray(document.body.children);
 * // => false
 *
 * _.isArray('abc');
 * // => false
 *
 * _.isArray(_.noop);
 * // => false
 */
var isArray$1 = Array.isArray;

var isArray$2 = isArray$1;

/** Used to match a single whitespace character. */
var reWhitespace = /\s/;

/**
 * Used by `_.trim` and `_.trimEnd` to get the index of the last non-whitespace
 * character of `string`.
 *
 * @private
 * @param {string} string The string to inspect.
 * @returns {number} Returns the index of the last non-whitespace character.
 */
function trimmedEndIndex(string) {
  var index = string.length;

  while (index-- && reWhitespace.test(string.charAt(index))) {}
  return index;
}

/** Used to match leading whitespace. */
var reTrimStart = /^\s+/;

/**
 * The base implementation of `_.trim`.
 *
 * @private
 * @param {string} string The string to trim.
 * @returns {string} Returns the trimmed string.
 */
function baseTrim(string) {
  return string
    ? string.slice(0, trimmedEndIndex(string) + 1).replace(reTrimStart, '')
    : string;
}

/**
 * Checks if `value` is the
 * [language type](http://www.ecma-international.org/ecma-262/7.0/#sec-ecmascript-language-types)
 * of `Object`. (e.g. arrays, functions, objects, regexes, `new Number(0)`, and `new String('')`)
 *
 * @static
 * @memberOf _
 * @since 0.1.0
 * @category Lang
 * @param {*} value The value to check.
 * @returns {boolean} Returns `true` if `value` is an object, else `false`.
 * @example
 *
 * _.isObject({});
 * // => true
 *
 * _.isObject([1, 2, 3]);
 * // => true
 *
 * _.isObject(_.noop);
 * // => true
 *
 * _.isObject(null);
 * // => false
 */
function isObject$1(value) {
  var type = typeof value;
  return value != null && (type == 'object' || type == 'function');
}

/** Used as references for various `Number` constants. */
var NAN = 0 / 0;

/** Used to detect bad signed hexadecimal string values. */
var reIsBadHex = /^[-+]0x[0-9a-f]+$/i;

/** Used to detect binary string values. */
var reIsBinary = /^0b[01]+$/i;

/** Used to detect octal string values. */
var reIsOctal = /^0o[0-7]+$/i;

/** Built-in method references without a dependency on `root`. */
var freeParseInt = parseInt;

/**
 * Converts `value` to a number.
 *
 * @static
 * @memberOf _
 * @since 4.0.0
 * @category Lang
 * @param {*} value The value to process.
 * @returns {number} Returns the number.
 * @example
 *
 * _.toNumber(3.2);
 * // => 3.2
 *
 * _.toNumber(Number.MIN_VALUE);
 * // => 5e-324
 *
 * _.toNumber(Infinity);
 * // => Infinity
 *
 * _.toNumber('3.2');
 * // => 3.2
 */
function toNumber(value) {
  if (typeof value == 'number') {
    return value;
  }
  if (isSymbol$1(value)) {
    return NAN;
  }
  if (isObject$1(value)) {
    var other = typeof value.valueOf == 'function' ? value.valueOf() : value;
    value = isObject$1(other) ? (other + '') : other;
  }
  if (typeof value != 'string') {
    return value === 0 ? value : +value;
  }
  value = baseTrim(value);
  var isBinary = reIsBinary.test(value);
  return (isBinary || reIsOctal.test(value))
    ? freeParseInt(value.slice(2), isBinary ? 2 : 8)
    : (reIsBadHex.test(value) ? NAN : +value);
}

/**
 * This method returns the first argument it receives.
 *
 * @static
 * @since 0.1.0
 * @memberOf _
 * @category Util
 * @param {*} value Any value.
 * @returns {*} Returns `value`.
 * @example
 *
 * var object = { 'a': 1 };
 *
 * console.log(_.identity(object) === object);
 * // => true
 */
function identity(value) {
  return value;
}

/** `Object#toString` result references. */
var asyncTag = '[object AsyncFunction]',
    funcTag$1 = '[object Function]',
    genTag = '[object GeneratorFunction]',
    proxyTag = '[object Proxy]';

/**
 * Checks if `value` is classified as a `Function` object.
 *
 * @static
 * @memberOf _
 * @since 0.1.0
 * @category Lang
 * @param {*} value The value to check.
 * @returns {boolean} Returns `true` if `value` is a function, else `false`.
 * @example
 *
 * _.isFunction(_);
 * // => true
 *
 * _.isFunction(/abc/);
 * // => false
 */
function isFunction$1(value) {
  if (!isObject$1(value)) {
    return false;
  }
  // The use of `Object#toString` avoids issues with the `typeof` operator
  // in Safari 9 which returns 'object' for typed arrays and other constructors.
  var tag = baseGetTag(value);
  return tag == funcTag$1 || tag == genTag || tag == asyncTag || tag == proxyTag;
}

/** Used to detect overreaching core-js shims. */
var coreJsData = root$1['__core-js_shared__'];

var coreJsData$1 = coreJsData;

/** Used to detect methods masquerading as native. */
var maskSrcKey = (function() {
  var uid = /[^.]+$/.exec(coreJsData$1 && coreJsData$1.keys && coreJsData$1.keys.IE_PROTO || '');
  return uid ? ('Symbol(src)_1.' + uid) : '';
}());

/**
 * Checks if `func` has its source masked.
 *
 * @private
 * @param {Function} func The function to check.
 * @returns {boolean} Returns `true` if `func` is masked, else `false`.
 */
function isMasked(func) {
  return !!maskSrcKey && (maskSrcKey in func);
}

/** Used for built-in method references. */
var funcProto$2 = Function.prototype;

/** Used to resolve the decompiled source of functions. */
var funcToString$2 = funcProto$2.toString;

/**
 * Converts `func` to its source code.
 *
 * @private
 * @param {Function} func The function to convert.
 * @returns {string} Returns the source code.
 */
function toSource(func) {
  if (func != null) {
    try {
      return funcToString$2.call(func);
    } catch (e) {}
    try {
      return (func + '');
    } catch (e) {}
  }
  return '';
}

/**
 * Used to match `RegExp`
 * [syntax characters](http://ecma-international.org/ecma-262/7.0/#sec-patterns).
 */
var reRegExpChar = /[\\^$.*+?()[\]{}|]/g;

/** Used to detect host constructors (Safari). */
var reIsHostCtor = /^\[object .+?Constructor\]$/;

/** Used for built-in method references. */
var funcProto$1 = Function.prototype,
    objectProto$8 = Object.prototype;

/** Used to resolve the decompiled source of functions. */
var funcToString$1 = funcProto$1.toString;

/** Used to check objects for own properties. */
var hasOwnProperty$7 = objectProto$8.hasOwnProperty;

/** Used to detect if a method is native. */
var reIsNative = RegExp('^' +
  funcToString$1.call(hasOwnProperty$7).replace(reRegExpChar, '\\$&')
  .replace(/hasOwnProperty|(function).*?(?=\\\()| for .+?(?=\\\])/g, '$1.*?') + '$'
);

/**
 * The base implementation of `_.isNative` without bad shim checks.
 *
 * @private
 * @param {*} value The value to check.
 * @returns {boolean} Returns `true` if `value` is a native function,
 *  else `false`.
 */
function baseIsNative(value) {
  if (!isObject$1(value) || isMasked(value)) {
    return false;
  }
  var pattern = isFunction$1(value) ? reIsNative : reIsHostCtor;
  return pattern.test(toSource(value));
}

/**
 * Gets the value at `key` of `object`.
 *
 * @private
 * @param {Object} [object] The object to query.
 * @param {string} key The key of the property to get.
 * @returns {*} Returns the property value.
 */
function getValue(object, key) {
  return object == null ? undefined : object[key];
}

/**
 * Gets the native function at `key` of `object`.
 *
 * @private
 * @param {Object} object The object to query.
 * @param {string} key The key of the method to get.
 * @returns {*} Returns the function if it's native, else `undefined`.
 */
function getNative(object, key) {
  var value = getValue(object, key);
  return baseIsNative(value) ? value : undefined;
}

/** Built-in value references. */
var objectCreate = Object.create;

/**
 * The base implementation of `_.create` without support for assigning
 * properties to the created object.
 *
 * @private
 * @param {Object} proto The object to inherit from.
 * @returns {Object} Returns the new object.
 */
var baseCreate = (function() {
  function object() {}
  return function(proto) {
    if (!isObject$1(proto)) {
      return {};
    }
    if (objectCreate) {
      return objectCreate(proto);
    }
    object.prototype = proto;
    var result = new object;
    object.prototype = undefined;
    return result;
  };
}());

var baseCreate$1 = baseCreate;

/**
 * A faster alternative to `Function#apply`, this function invokes `func`
 * with the `this` binding of `thisArg` and the arguments of `args`.
 *
 * @private
 * @param {Function} func The function to invoke.
 * @param {*} thisArg The `this` binding of `func`.
 * @param {Array} args The arguments to invoke `func` with.
 * @returns {*} Returns the result of `func`.
 */
function apply(func, thisArg, args) {
  switch (args.length) {
    case 0: return func.call(thisArg);
    case 1: return func.call(thisArg, args[0]);
    case 2: return func.call(thisArg, args[0], args[1]);
    case 3: return func.call(thisArg, args[0], args[1], args[2]);
  }
  return func.apply(thisArg, args);
}

/**
 * Copies the values of `source` to `array`.
 *
 * @private
 * @param {Array} source The array to copy values from.
 * @param {Array} [array=[]] The array to copy values to.
 * @returns {Array} Returns `array`.
 */
function copyArray(source, array) {
  var index = -1,
      length = source.length;

  array || (array = Array(length));
  while (++index < length) {
    array[index] = source[index];
  }
  return array;
}

/** Used to detect hot functions by number of calls within a span of milliseconds. */
var HOT_COUNT = 800,
    HOT_SPAN = 16;

/* Built-in method references for those with the same name as other `lodash` methods. */
var nativeNow = Date.now;

/**
 * Creates a function that'll short out and invoke `identity` instead
 * of `func` when it's called `HOT_COUNT` or more times in `HOT_SPAN`
 * milliseconds.
 *
 * @private
 * @param {Function} func The function to restrict.
 * @returns {Function} Returns the new shortable function.
 */
function shortOut(func) {
  var count = 0,
      lastCalled = 0;

  return function() {
    var stamp = nativeNow(),
        remaining = HOT_SPAN - (stamp - lastCalled);

    lastCalled = stamp;
    if (remaining > 0) {
      if (++count >= HOT_COUNT) {
        return arguments[0];
      }
    } else {
      count = 0;
    }
    return func.apply(undefined, arguments);
  };
}

/**
 * Creates a function that returns `value`.
 *
 * @static
 * @memberOf _
 * @since 2.4.0
 * @category Util
 * @param {*} value The value to return from the new function.
 * @returns {Function} Returns the new constant function.
 * @example
 *
 * var objects = _.times(2, _.constant({ 'a': 1 }));
 *
 * console.log(objects);
 * // => [{ 'a': 1 }, { 'a': 1 }]
 *
 * console.log(objects[0] === objects[1]);
 * // => true
 */
function constant(value) {
  return function() {
    return value;
  };
}

var defineProperty = (function() {
  try {
    var func = getNative(Object, 'defineProperty');
    func({}, '', {});
    return func;
  } catch (e) {}
}());

var defineProperty$1 = defineProperty;

/**
 * The base implementation of `setToString` without support for hot loop shorting.
 *
 * @private
 * @param {Function} func The function to modify.
 * @param {Function} string The `toString` result.
 * @returns {Function} Returns `func`.
 */
var baseSetToString = !defineProperty$1 ? identity : function(func, string) {
  return defineProperty$1(func, 'toString', {
    'configurable': true,
    'enumerable': false,
    'value': constant(string),
    'writable': true
  });
};

var baseSetToString$1 = baseSetToString;

/**
 * Sets the `toString` method of `func` to return `string`.
 *
 * @private
 * @param {Function} func The function to modify.
 * @param {Function} string The `toString` result.
 * @returns {Function} Returns `func`.
 */
var setToString = shortOut(baseSetToString$1);

var setToString$1 = setToString;

/** Used as references for various `Number` constants. */
var MAX_SAFE_INTEGER$1 = 9007199254740991;

/** Used to detect unsigned integer values. */
var reIsUint = /^(?:0|[1-9]\d*)$/;

/**
 * Checks if `value` is a valid array-like index.
 *
 * @private
 * @param {*} value The value to check.
 * @param {number} [length=MAX_SAFE_INTEGER] The upper bounds of a valid index.
 * @returns {boolean} Returns `true` if `value` is a valid index, else `false`.
 */
function isIndex(value, length) {
  var type = typeof value;
  length = length == null ? MAX_SAFE_INTEGER$1 : length;

  return !!length &&
    (type == 'number' ||
      (type != 'symbol' && reIsUint.test(value))) &&
        (value > -1 && value % 1 == 0 && value < length);
}

/**
 * The base implementation of `assignValue` and `assignMergeValue` without
 * value checks.
 *
 * @private
 * @param {Object} object The object to modify.
 * @param {string} key The key of the property to assign.
 * @param {*} value The value to assign.
 */
function baseAssignValue(object, key, value) {
  if (key == '__proto__' && defineProperty$1) {
    defineProperty$1(object, key, {
      'configurable': true,
      'enumerable': true,
      'value': value,
      'writable': true
    });
  } else {
    object[key] = value;
  }
}

/**
 * Performs a
 * [`SameValueZero`](http://ecma-international.org/ecma-262/7.0/#sec-samevaluezero)
 * comparison between two values to determine if they are equivalent.
 *
 * @static
 * @memberOf _
 * @since 4.0.0
 * @category Lang
 * @param {*} value The value to compare.
 * @param {*} other The other value to compare.
 * @returns {boolean} Returns `true` if the values are equivalent, else `false`.
 * @example
 *
 * var object = { 'a': 1 };
 * var other = { 'a': 1 };
 *
 * _.eq(object, object);
 * // => true
 *
 * _.eq(object, other);
 * // => false
 *
 * _.eq('a', 'a');
 * // => true
 *
 * _.eq('a', Object('a'));
 * // => false
 *
 * _.eq(NaN, NaN);
 * // => true
 */
function eq(value, other) {
  return value === other || (value !== value && other !== other);
}

/** Used for built-in method references. */
var objectProto$7 = Object.prototype;

/** Used to check objects for own properties. */
var hasOwnProperty$6 = objectProto$7.hasOwnProperty;

/**
 * Assigns `value` to `key` of `object` if the existing value is not equivalent
 * using [`SameValueZero`](http://ecma-international.org/ecma-262/7.0/#sec-samevaluezero)
 * for equality comparisons.
 *
 * @private
 * @param {Object} object The object to modify.
 * @param {string} key The key of the property to assign.
 * @param {*} value The value to assign.
 */
function assignValue(object, key, value) {
  var objValue = object[key];
  if (!(hasOwnProperty$6.call(object, key) && eq(objValue, value)) ||
      (value === undefined && !(key in object))) {
    baseAssignValue(object, key, value);
  }
}

/**
 * Copies properties of `source` to `object`.
 *
 * @private
 * @param {Object} source The object to copy properties from.
 * @param {Array} props The property identifiers to copy.
 * @param {Object} [object={}] The object to copy properties to.
 * @param {Function} [customizer] The function to customize copied values.
 * @returns {Object} Returns `object`.
 */
function copyObject(source, props, object, customizer) {
  var isNew = !object;
  object || (object = {});

  var index = -1,
      length = props.length;

  while (++index < length) {
    var key = props[index];

    var newValue = customizer
      ? customizer(object[key], source[key], key, object, source)
      : undefined;

    if (newValue === undefined) {
      newValue = source[key];
    }
    if (isNew) {
      baseAssignValue(object, key, newValue);
    } else {
      assignValue(object, key, newValue);
    }
  }
  return object;
}

/* Built-in method references for those with the same name as other `lodash` methods. */
var nativeMax$1 = Math.max;

/**
 * A specialized version of `baseRest` which transforms the rest array.
 *
 * @private
 * @param {Function} func The function to apply a rest parameter to.
 * @param {number} [start=func.length-1] The start position of the rest parameter.
 * @param {Function} transform The rest array transform.
 * @returns {Function} Returns the new function.
 */
function overRest(func, start, transform) {
  start = nativeMax$1(start === undefined ? (func.length - 1) : start, 0);
  return function() {
    var args = arguments,
        index = -1,
        length = nativeMax$1(args.length - start, 0),
        array = Array(length);

    while (++index < length) {
      array[index] = args[start + index];
    }
    index = -1;
    var otherArgs = Array(start + 1);
    while (++index < start) {
      otherArgs[index] = args[index];
    }
    otherArgs[start] = transform(array);
    return apply(func, this, otherArgs);
  };
}

/**
 * The base implementation of `_.rest` which doesn't validate or coerce arguments.
 *
 * @private
 * @param {Function} func The function to apply a rest parameter to.
 * @param {number} [start=func.length-1] The start position of the rest parameter.
 * @returns {Function} Returns the new function.
 */
function baseRest(func, start) {
  return setToString$1(overRest(func, start, identity), func + '');
}

/** Used as references for various `Number` constants. */
var MAX_SAFE_INTEGER = 9007199254740991;

/**
 * Checks if `value` is a valid array-like length.
 *
 * **Note:** This method is loosely based on
 * [`ToLength`](http://ecma-international.org/ecma-262/7.0/#sec-tolength).
 *
 * @static
 * @memberOf _
 * @since 4.0.0
 * @category Lang
 * @param {*} value The value to check.
 * @returns {boolean} Returns `true` if `value` is a valid length, else `false`.
 * @example
 *
 * _.isLength(3);
 * // => true
 *
 * _.isLength(Number.MIN_VALUE);
 * // => false
 *
 * _.isLength(Infinity);
 * // => false
 *
 * _.isLength('3');
 * // => false
 */
function isLength(value) {
  return typeof value == 'number' &&
    value > -1 && value % 1 == 0 && value <= MAX_SAFE_INTEGER;
}

/**
 * Checks if `value` is array-like. A value is considered array-like if it's
 * not a function and has a `value.length` that's an integer greater than or
 * equal to `0` and less than or equal to `Number.MAX_SAFE_INTEGER`.
 *
 * @static
 * @memberOf _
 * @since 4.0.0
 * @category Lang
 * @param {*} value The value to check.
 * @returns {boolean} Returns `true` if `value` is array-like, else `false`.
 * @example
 *
 * _.isArrayLike([1, 2, 3]);
 * // => true
 *
 * _.isArrayLike(document.body.children);
 * // => true
 *
 * _.isArrayLike('abc');
 * // => true
 *
 * _.isArrayLike(_.noop);
 * // => false
 */
function isArrayLike(value) {
  return value != null && isLength(value.length) && !isFunction$1(value);
}

/**
 * Checks if the given arguments are from an iteratee call.
 *
 * @private
 * @param {*} value The potential iteratee value argument.
 * @param {*} index The potential iteratee index or key argument.
 * @param {*} object The potential iteratee object argument.
 * @returns {boolean} Returns `true` if the arguments are from an iteratee call,
 *  else `false`.
 */
function isIterateeCall(value, index, object) {
  if (!isObject$1(object)) {
    return false;
  }
  var type = typeof index;
  if (type == 'number'
        ? (isArrayLike(object) && isIndex(index, object.length))
        : (type == 'string' && index in object)
      ) {
    return eq(object[index], value);
  }
  return false;
}

/**
 * Creates a function like `_.assign`.
 *
 * @private
 * @param {Function} assigner The function to assign values.
 * @returns {Function} Returns the new assigner function.
 */
function createAssigner(assigner) {
  return baseRest(function(object, sources) {
    var index = -1,
        length = sources.length,
        customizer = length > 1 ? sources[length - 1] : undefined,
        guard = length > 2 ? sources[2] : undefined;

    customizer = (assigner.length > 3 && typeof customizer == 'function')
      ? (length--, customizer)
      : undefined;

    if (guard && isIterateeCall(sources[0], sources[1], guard)) {
      customizer = length < 3 ? undefined : customizer;
      length = 1;
    }
    object = Object(object);
    while (++index < length) {
      var source = sources[index];
      if (source) {
        assigner(object, source, index, customizer);
      }
    }
    return object;
  });
}

/** Used for built-in method references. */
var objectProto$6 = Object.prototype;

/**
 * Checks if `value` is likely a prototype object.
 *
 * @private
 * @param {*} value The value to check.
 * @returns {boolean} Returns `true` if `value` is a prototype, else `false`.
 */
function isPrototype(value) {
  var Ctor = value && value.constructor,
      proto = (typeof Ctor == 'function' && Ctor.prototype) || objectProto$6;

  return value === proto;
}

/**
 * The base implementation of `_.times` without support for iteratee shorthands
 * or max array length checks.
 *
 * @private
 * @param {number} n The number of times to invoke `iteratee`.
 * @param {Function} iteratee The function invoked per iteration.
 * @returns {Array} Returns the array of results.
 */
function baseTimes(n, iteratee) {
  var index = -1,
      result = Array(n);

  while (++index < n) {
    result[index] = iteratee(index);
  }
  return result;
}

/** `Object#toString` result references. */
var argsTag$1 = '[object Arguments]';

/**
 * The base implementation of `_.isArguments`.
 *
 * @private
 * @param {*} value The value to check.
 * @returns {boolean} Returns `true` if `value` is an `arguments` object,
 */
function baseIsArguments(value) {
  return isObjectLike(value) && baseGetTag(value) == argsTag$1;
}

/** Used for built-in method references. */
var objectProto$5 = Object.prototype;

/** Used to check objects for own properties. */
var hasOwnProperty$5 = objectProto$5.hasOwnProperty;

/** Built-in value references. */
var propertyIsEnumerable = objectProto$5.propertyIsEnumerable;

/**
 * Checks if `value` is likely an `arguments` object.
 *
 * @static
 * @memberOf _
 * @since 0.1.0
 * @category Lang
 * @param {*} value The value to check.
 * @returns {boolean} Returns `true` if `value` is an `arguments` object,
 *  else `false`.
 * @example
 *
 * _.isArguments(function() { return arguments; }());
 * // => true
 *
 * _.isArguments([1, 2, 3]);
 * // => false
 */
var isArguments = baseIsArguments(function() { return arguments; }()) ? baseIsArguments : function(value) {
  return isObjectLike(value) && hasOwnProperty$5.call(value, 'callee') &&
    !propertyIsEnumerable.call(value, 'callee');
};

var isArguments$1 = isArguments;

/**
 * This method returns `false`.
 *
 * @static
 * @memberOf _
 * @since 4.13.0
 * @category Util
 * @returns {boolean} Returns `false`.
 * @example
 *
 * _.times(2, _.stubFalse);
 * // => [false, false]
 */
function stubFalse() {
  return false;
}

/** Detect free variable `exports`. */
var freeExports$2 = typeof exports == 'object' && exports && !exports.nodeType && exports;

/** Detect free variable `module`. */
var freeModule$2 = freeExports$2 && typeof module == 'object' && module && !module.nodeType && module;

/** Detect the popular CommonJS extension `module.exports`. */
var moduleExports$2 = freeModule$2 && freeModule$2.exports === freeExports$2;

/** Built-in value references. */
var Buffer$1 = moduleExports$2 ? root$1.Buffer : undefined;

/* Built-in method references for those with the same name as other `lodash` methods. */
var nativeIsBuffer = Buffer$1 ? Buffer$1.isBuffer : undefined;

/**
 * Checks if `value` is a buffer.
 *
 * @static
 * @memberOf _
 * @since 4.3.0
 * @category Lang
 * @param {*} value The value to check.
 * @returns {boolean} Returns `true` if `value` is a buffer, else `false`.
 * @example
 *
 * _.isBuffer(new Buffer(2));
 * // => true
 *
 * _.isBuffer(new Uint8Array(2));
 * // => false
 */
var isBuffer = nativeIsBuffer || stubFalse;

var isBuffer$1 = isBuffer;

/** `Object#toString` result references. */
var argsTag = '[object Arguments]',
    arrayTag = '[object Array]',
    boolTag = '[object Boolean]',
    dateTag = '[object Date]',
    errorTag = '[object Error]',
    funcTag = '[object Function]',
    mapTag = '[object Map]',
    numberTag = '[object Number]',
    objectTag$1 = '[object Object]',
    regexpTag = '[object RegExp]',
    setTag = '[object Set]',
    stringTag = '[object String]',
    weakMapTag = '[object WeakMap]';

var arrayBufferTag = '[object ArrayBuffer]',
    dataViewTag = '[object DataView]',
    float32Tag = '[object Float32Array]',
    float64Tag = '[object Float64Array]',
    int8Tag = '[object Int8Array]',
    int16Tag = '[object Int16Array]',
    int32Tag = '[object Int32Array]',
    uint8Tag = '[object Uint8Array]',
    uint8ClampedTag = '[object Uint8ClampedArray]',
    uint16Tag = '[object Uint16Array]',
    uint32Tag = '[object Uint32Array]';

/** Used to identify `toStringTag` values of typed arrays. */
var typedArrayTags = {};
typedArrayTags[float32Tag] = typedArrayTags[float64Tag] =
typedArrayTags[int8Tag] = typedArrayTags[int16Tag] =
typedArrayTags[int32Tag] = typedArrayTags[uint8Tag] =
typedArrayTags[uint8ClampedTag] = typedArrayTags[uint16Tag] =
typedArrayTags[uint32Tag] = true;
typedArrayTags[argsTag] = typedArrayTags[arrayTag] =
typedArrayTags[arrayBufferTag] = typedArrayTags[boolTag] =
typedArrayTags[dataViewTag] = typedArrayTags[dateTag] =
typedArrayTags[errorTag] = typedArrayTags[funcTag] =
typedArrayTags[mapTag] = typedArrayTags[numberTag] =
typedArrayTags[objectTag$1] = typedArrayTags[regexpTag] =
typedArrayTags[setTag] = typedArrayTags[stringTag] =
typedArrayTags[weakMapTag] = false;

/**
 * The base implementation of `_.isTypedArray` without Node.js optimizations.
 *
 * @private
 * @param {*} value The value to check.
 * @returns {boolean} Returns `true` if `value` is a typed array, else `false`.
 */
function baseIsTypedArray(value) {
  return isObjectLike(value) &&
    isLength(value.length) && !!typedArrayTags[baseGetTag(value)];
}

/**
 * The base implementation of `_.unary` without support for storing metadata.
 *
 * @private
 * @param {Function} func The function to cap arguments for.
 * @returns {Function} Returns the new capped function.
 */
function baseUnary(func) {
  return function(value) {
    return func(value);
  };
}

/** Detect free variable `exports`. */
var freeExports$1 = typeof exports == 'object' && exports && !exports.nodeType && exports;

/** Detect free variable `module`. */
var freeModule$1 = freeExports$1 && typeof module == 'object' && module && !module.nodeType && module;

/** Detect the popular CommonJS extension `module.exports`. */
var moduleExports$1 = freeModule$1 && freeModule$1.exports === freeExports$1;

/** Detect free variable `process` from Node.js. */
var freeProcess = moduleExports$1 && freeGlobal$1.process;

/** Used to access faster Node.js helpers. */
var nodeUtil = (function() {
  try {
    // Use `util.types` for Node.js 10+.
    var types = freeModule$1 && freeModule$1.require && freeModule$1.require('util').types;

    if (types) {
      return types;
    }

    // Legacy `process.binding('util')` for Node.js < 10.
    return freeProcess && freeProcess.binding && freeProcess.binding('util');
  } catch (e) {}
}());

var nodeUtil$1 = nodeUtil;

/* Node.js helper references. */
var nodeIsTypedArray = nodeUtil$1 && nodeUtil$1.isTypedArray;

/**
 * Checks if `value` is classified as a typed array.
 *
 * @static
 * @memberOf _
 * @since 3.0.0
 * @category Lang
 * @param {*} value The value to check.
 * @returns {boolean} Returns `true` if `value` is a typed array, else `false`.
 * @example
 *
 * _.isTypedArray(new Uint8Array);
 * // => true
 *
 * _.isTypedArray([]);
 * // => false
 */
var isTypedArray = nodeIsTypedArray ? baseUnary(nodeIsTypedArray) : baseIsTypedArray;

var isTypedArray$1 = isTypedArray;

/** Used for built-in method references. */
var objectProto$4 = Object.prototype;

/** Used to check objects for own properties. */
var hasOwnProperty$4 = objectProto$4.hasOwnProperty;

/**
 * Creates an array of the enumerable property names of the array-like `value`.
 *
 * @private
 * @param {*} value The value to query.
 * @param {boolean} inherited Specify returning inherited property names.
 * @returns {Array} Returns the array of property names.
 */
function arrayLikeKeys(value, inherited) {
  var isArr = isArray$2(value),
      isArg = !isArr && isArguments$1(value),
      isBuff = !isArr && !isArg && isBuffer$1(value),
      isType = !isArr && !isArg && !isBuff && isTypedArray$1(value),
      skipIndexes = isArr || isArg || isBuff || isType,
      result = skipIndexes ? baseTimes(value.length, String) : [],
      length = result.length;

  for (var key in value) {
    if ((inherited || hasOwnProperty$4.call(value, key)) &&
        !(skipIndexes && (
           // Safari 9 has enumerable `arguments.length` in strict mode.
           key == 'length' ||
           // Node.js 0.10 has enumerable non-index properties on buffers.
           (isBuff && (key == 'offset' || key == 'parent')) ||
           // PhantomJS 2 has enumerable non-index properties on typed arrays.
           (isType && (key == 'buffer' || key == 'byteLength' || key == 'byteOffset')) ||
           // Skip index properties.
           isIndex(key, length)
        ))) {
      result.push(key);
    }
  }
  return result;
}

/**
 * Creates a unary function that invokes `func` with its argument transformed.
 *
 * @private
 * @param {Function} func The function to wrap.
 * @param {Function} transform The argument transform.
 * @returns {Function} Returns the new function.
 */
function overArg(func, transform) {
  return function(arg) {
    return func(transform(arg));
  };
}

/**
 * This function is like
 * [`Object.keys`](http://ecma-international.org/ecma-262/7.0/#sec-object.keys)
 * except that it includes inherited enumerable properties.
 *
 * @private
 * @param {Object} object The object to query.
 * @returns {Array} Returns the array of property names.
 */
function nativeKeysIn(object) {
  var result = [];
  if (object != null) {
    for (var key in Object(object)) {
      result.push(key);
    }
  }
  return result;
}

/** Used for built-in method references. */
var objectProto$3 = Object.prototype;

/** Used to check objects for own properties. */
var hasOwnProperty$3 = objectProto$3.hasOwnProperty;

/**
 * The base implementation of `_.keysIn` which doesn't treat sparse arrays as dense.
 *
 * @private
 * @param {Object} object The object to query.
 * @returns {Array} Returns the array of property names.
 */
function baseKeysIn(object) {
  if (!isObject$1(object)) {
    return nativeKeysIn(object);
  }
  var isProto = isPrototype(object),
      result = [];

  for (var key in object) {
    if (!(key == 'constructor' && (isProto || !hasOwnProperty$3.call(object, key)))) {
      result.push(key);
    }
  }
  return result;
}

/**
 * Creates an array of the own and inherited enumerable property names of `object`.
 *
 * **Note:** Non-object values are coerced to objects.
 *
 * @static
 * @memberOf _
 * @since 3.0.0
 * @category Object
 * @param {Object} object The object to query.
 * @returns {Array} Returns the array of property names.
 * @example
 *
 * function Foo() {
 *   this.a = 1;
 *   this.b = 2;
 * }
 *
 * Foo.prototype.c = 3;
 *
 * _.keysIn(new Foo);
 * // => ['a', 'b', 'c'] (iteration order is not guaranteed)
 */
function keysIn(object) {
  return isArrayLike(object) ? arrayLikeKeys(object, true) : baseKeysIn(object);
}

/* Built-in method references that are verified to be native. */
var nativeCreate = getNative(Object, 'create');

var nativeCreate$1 = nativeCreate;

/**
 * Removes all key-value entries from the hash.
 *
 * @private
 * @name clear
 * @memberOf Hash
 */
function hashClear() {
  this.__data__ = nativeCreate$1 ? nativeCreate$1(null) : {};
  this.size = 0;
}

/**
 * Removes `key` and its value from the hash.
 *
 * @private
 * @name delete
 * @memberOf Hash
 * @param {Object} hash The hash to modify.
 * @param {string} key The key of the value to remove.
 * @returns {boolean} Returns `true` if the entry was removed, else `false`.
 */
function hashDelete(key) {
  var result = this.has(key) && delete this.__data__[key];
  this.size -= result ? 1 : 0;
  return result;
}

/** Used to stand-in for `undefined` hash values. */
var HASH_UNDEFINED$1 = '__lodash_hash_undefined__';

/** Used for built-in method references. */
var objectProto$2 = Object.prototype;

/** Used to check objects for own properties. */
var hasOwnProperty$2 = objectProto$2.hasOwnProperty;

/**
 * Gets the hash value for `key`.
 *
 * @private
 * @name get
 * @memberOf Hash
 * @param {string} key The key of the value to get.
 * @returns {*} Returns the entry value.
 */
function hashGet(key) {
  var data = this.__data__;
  if (nativeCreate$1) {
    var result = data[key];
    return result === HASH_UNDEFINED$1 ? undefined : result;
  }
  return hasOwnProperty$2.call(data, key) ? data[key] : undefined;
}

/** Used for built-in method references. */
var objectProto$1 = Object.prototype;

/** Used to check objects for own properties. */
var hasOwnProperty$1 = objectProto$1.hasOwnProperty;

/**
 * Checks if a hash value for `key` exists.
 *
 * @private
 * @name has
 * @memberOf Hash
 * @param {string} key The key of the entry to check.
 * @returns {boolean} Returns `true` if an entry for `key` exists, else `false`.
 */
function hashHas(key) {
  var data = this.__data__;
  return nativeCreate$1 ? (data[key] !== undefined) : hasOwnProperty$1.call(data, key);
}

/** Used to stand-in for `undefined` hash values. */
var HASH_UNDEFINED = '__lodash_hash_undefined__';

/**
 * Sets the hash `key` to `value`.
 *
 * @private
 * @name set
 * @memberOf Hash
 * @param {string} key The key of the value to set.
 * @param {*} value The value to set.
 * @returns {Object} Returns the hash instance.
 */
function hashSet(key, value) {
  var data = this.__data__;
  this.size += this.has(key) ? 0 : 1;
  data[key] = (nativeCreate$1 && value === undefined) ? HASH_UNDEFINED : value;
  return this;
}

/**
 * Creates a hash object.
 *
 * @private
 * @constructor
 * @param {Array} [entries] The key-value pairs to cache.
 */
function Hash(entries) {
  var index = -1,
      length = entries == null ? 0 : entries.length;

  this.clear();
  while (++index < length) {
    var entry = entries[index];
    this.set(entry[0], entry[1]);
  }
}

// Add methods to `Hash`.
Hash.prototype.clear = hashClear;
Hash.prototype['delete'] = hashDelete;
Hash.prototype.get = hashGet;
Hash.prototype.has = hashHas;
Hash.prototype.set = hashSet;

/**
 * Removes all key-value entries from the list cache.
 *
 * @private
 * @name clear
 * @memberOf ListCache
 */
function listCacheClear() {
  this.__data__ = [];
  this.size = 0;
}

/**
 * Gets the index at which the `key` is found in `array` of key-value pairs.
 *
 * @private
 * @param {Array} array The array to inspect.
 * @param {*} key The key to search for.
 * @returns {number} Returns the index of the matched value, else `-1`.
 */
function assocIndexOf(array, key) {
  var length = array.length;
  while (length--) {
    if (eq(array[length][0], key)) {
      return length;
    }
  }
  return -1;
}

/** Used for built-in method references. */
var arrayProto = Array.prototype;

/** Built-in value references. */
var splice = arrayProto.splice;

/**
 * Removes `key` and its value from the list cache.
 *
 * @private
 * @name delete
 * @memberOf ListCache
 * @param {string} key The key of the value to remove.
 * @returns {boolean} Returns `true` if the entry was removed, else `false`.
 */
function listCacheDelete(key) {
  var data = this.__data__,
      index = assocIndexOf(data, key);

  if (index < 0) {
    return false;
  }
  var lastIndex = data.length - 1;
  if (index == lastIndex) {
    data.pop();
  } else {
    splice.call(data, index, 1);
  }
  --this.size;
  return true;
}

/**
 * Gets the list cache value for `key`.
 *
 * @private
 * @name get
 * @memberOf ListCache
 * @param {string} key The key of the value to get.
 * @returns {*} Returns the entry value.
 */
function listCacheGet(key) {
  var data = this.__data__,
      index = assocIndexOf(data, key);

  return index < 0 ? undefined : data[index][1];
}

/**
 * Checks if a list cache value for `key` exists.
 *
 * @private
 * @name has
 * @memberOf ListCache
 * @param {string} key The key of the entry to check.
 * @returns {boolean} Returns `true` if an entry for `key` exists, else `false`.
 */
function listCacheHas(key) {
  return assocIndexOf(this.__data__, key) > -1;
}

/**
 * Sets the list cache `key` to `value`.
 *
 * @private
 * @name set
 * @memberOf ListCache
 * @param {string} key The key of the value to set.
 * @param {*} value The value to set.
 * @returns {Object} Returns the list cache instance.
 */
function listCacheSet(key, value) {
  var data = this.__data__,
      index = assocIndexOf(data, key);

  if (index < 0) {
    ++this.size;
    data.push([key, value]);
  } else {
    data[index][1] = value;
  }
  return this;
}

/**
 * Creates an list cache object.
 *
 * @private
 * @constructor
 * @param {Array} [entries] The key-value pairs to cache.
 */
function ListCache(entries) {
  var index = -1,
      length = entries == null ? 0 : entries.length;

  this.clear();
  while (++index < length) {
    var entry = entries[index];
    this.set(entry[0], entry[1]);
  }
}

// Add methods to `ListCache`.
ListCache.prototype.clear = listCacheClear;
ListCache.prototype['delete'] = listCacheDelete;
ListCache.prototype.get = listCacheGet;
ListCache.prototype.has = listCacheHas;
ListCache.prototype.set = listCacheSet;

/* Built-in method references that are verified to be native. */
var Map$1 = getNative(root$1, 'Map');

var Map$2 = Map$1;

/**
 * Removes all key-value entries from the map.
 *
 * @private
 * @name clear
 * @memberOf MapCache
 */
function mapCacheClear() {
  this.size = 0;
  this.__data__ = {
    'hash': new Hash,
    'map': new (Map$2 || ListCache),
    'string': new Hash
  };
}

/**
 * Checks if `value` is suitable for use as unique object key.
 *
 * @private
 * @param {*} value The value to check.
 * @returns {boolean} Returns `true` if `value` is suitable, else `false`.
 */
function isKeyable(value) {
  var type = typeof value;
  return (type == 'string' || type == 'number' || type == 'symbol' || type == 'boolean')
    ? (value !== '__proto__')
    : (value === null);
}

/**
 * Gets the data for `map`.
 *
 * @private
 * @param {Object} map The map to query.
 * @param {string} key The reference key.
 * @returns {*} Returns the map data.
 */
function getMapData(map, key) {
  var data = map.__data__;
  return isKeyable(key)
    ? data[typeof key == 'string' ? 'string' : 'hash']
    : data.map;
}

/**
 * Removes `key` and its value from the map.
 *
 * @private
 * @name delete
 * @memberOf MapCache
 * @param {string} key The key of the value to remove.
 * @returns {boolean} Returns `true` if the entry was removed, else `false`.
 */
function mapCacheDelete(key) {
  var result = getMapData(this, key)['delete'](key);
  this.size -= result ? 1 : 0;
  return result;
}

/**
 * Gets the map value for `key`.
 *
 * @private
 * @name get
 * @memberOf MapCache
 * @param {string} key The key of the value to get.
 * @returns {*} Returns the entry value.
 */
function mapCacheGet(key) {
  return getMapData(this, key).get(key);
}

/**
 * Checks if a map value for `key` exists.
 *
 * @private
 * @name has
 * @memberOf MapCache
 * @param {string} key The key of the entry to check.
 * @returns {boolean} Returns `true` if an entry for `key` exists, else `false`.
 */
function mapCacheHas(key) {
  return getMapData(this, key).has(key);
}

/**
 * Sets the map `key` to `value`.
 *
 * @private
 * @name set
 * @memberOf MapCache
 * @param {string} key The key of the value to set.
 * @param {*} value The value to set.
 * @returns {Object} Returns the map cache instance.
 */
function mapCacheSet(key, value) {
  var data = getMapData(this, key),
      size = data.size;

  data.set(key, value);
  this.size += data.size == size ? 0 : 1;
  return this;
}

/**
 * Creates a map cache object to store key-value pairs.
 *
 * @private
 * @constructor
 * @param {Array} [entries] The key-value pairs to cache.
 */
function MapCache(entries) {
  var index = -1,
      length = entries == null ? 0 : entries.length;

  this.clear();
  while (++index < length) {
    var entry = entries[index];
    this.set(entry[0], entry[1]);
  }
}

// Add methods to `MapCache`.
MapCache.prototype.clear = mapCacheClear;
MapCache.prototype['delete'] = mapCacheDelete;
MapCache.prototype.get = mapCacheGet;
MapCache.prototype.has = mapCacheHas;
MapCache.prototype.set = mapCacheSet;

/** Built-in value references. */
var getPrototype = overArg(Object.getPrototypeOf, Object);

var getPrototype$1 = getPrototype;

/** `Object#toString` result references. */
var objectTag = '[object Object]';

/** Used for built-in method references. */
var funcProto = Function.prototype,
    objectProto = Object.prototype;

/** Used to resolve the decompiled source of functions. */
var funcToString = funcProto.toString;

/** Used to check objects for own properties. */
var hasOwnProperty = objectProto.hasOwnProperty;

/** Used to infer the `Object` constructor. */
var objectCtorString = funcToString.call(Object);

/**
 * Checks if `value` is a plain object, that is, an object created by the
 * `Object` constructor or one with a `[[Prototype]]` of `null`.
 *
 * @static
 * @memberOf _
 * @since 0.8.0
 * @category Lang
 * @param {*} value The value to check.
 * @returns {boolean} Returns `true` if `value` is a plain object, else `false`.
 * @example
 *
 * function Foo() {
 *   this.a = 1;
 * }
 *
 * _.isPlainObject(new Foo);
 * // => false
 *
 * _.isPlainObject([1, 2, 3]);
 * // => false
 *
 * _.isPlainObject({ 'x': 0, 'y': 0 });
 * // => true
 *
 * _.isPlainObject(Object.create(null));
 * // => true
 */
function isPlainObject(value) {
  if (!isObjectLike(value) || baseGetTag(value) != objectTag) {
    return false;
  }
  var proto = getPrototype$1(value);
  if (proto === null) {
    return true;
  }
  var Ctor = hasOwnProperty.call(proto, 'constructor') && proto.constructor;
  return typeof Ctor == 'function' && Ctor instanceof Ctor &&
    funcToString.call(Ctor) == objectCtorString;
}

/**
 * Removes all key-value entries from the stack.
 *
 * @private
 * @name clear
 * @memberOf Stack
 */
function stackClear() {
  this.__data__ = new ListCache;
  this.size = 0;
}

/**
 * Removes `key` and its value from the stack.
 *
 * @private
 * @name delete
 * @memberOf Stack
 * @param {string} key The key of the value to remove.
 * @returns {boolean} Returns `true` if the entry was removed, else `false`.
 */
function stackDelete(key) {
  var data = this.__data__,
      result = data['delete'](key);

  this.size = data.size;
  return result;
}

/**
 * Gets the stack value for `key`.
 *
 * @private
 * @name get
 * @memberOf Stack
 * @param {string} key The key of the value to get.
 * @returns {*} Returns the entry value.
 */
function stackGet(key) {
  return this.__data__.get(key);
}

/**
 * Checks if a stack value for `key` exists.
 *
 * @private
 * @name has
 * @memberOf Stack
 * @param {string} key The key of the entry to check.
 * @returns {boolean} Returns `true` if an entry for `key` exists, else `false`.
 */
function stackHas(key) {
  return this.__data__.has(key);
}

/** Used as the size to enable large array optimizations. */
var LARGE_ARRAY_SIZE = 200;

/**
 * Sets the stack `key` to `value`.
 *
 * @private
 * @name set
 * @memberOf Stack
 * @param {string} key The key of the value to set.
 * @param {*} value The value to set.
 * @returns {Object} Returns the stack cache instance.
 */
function stackSet(key, value) {
  var data = this.__data__;
  if (data instanceof ListCache) {
    var pairs = data.__data__;
    if (!Map$2 || (pairs.length < LARGE_ARRAY_SIZE - 1)) {
      pairs.push([key, value]);
      this.size = ++data.size;
      return this;
    }
    data = this.__data__ = new MapCache(pairs);
  }
  data.set(key, value);
  this.size = data.size;
  return this;
}

/**
 * Creates a stack cache object to store key-value pairs.
 *
 * @private
 * @constructor
 * @param {Array} [entries] The key-value pairs to cache.
 */
function Stack(entries) {
  var data = this.__data__ = new ListCache(entries);
  this.size = data.size;
}

// Add methods to `Stack`.
Stack.prototype.clear = stackClear;
Stack.prototype['delete'] = stackDelete;
Stack.prototype.get = stackGet;
Stack.prototype.has = stackHas;
Stack.prototype.set = stackSet;

/** Detect free variable `exports`. */
var freeExports = typeof exports == 'object' && exports && !exports.nodeType && exports;

/** Detect free variable `module`. */
var freeModule = freeExports && typeof module == 'object' && module && !module.nodeType && module;

/** Detect the popular CommonJS extension `module.exports`. */
var moduleExports = freeModule && freeModule.exports === freeExports;

/** Built-in value references. */
var Buffer = moduleExports ? root$1.Buffer : undefined,
    allocUnsafe = Buffer ? Buffer.allocUnsafe : undefined;

/**
 * Creates a clone of  `buffer`.
 *
 * @private
 * @param {Buffer} buffer The buffer to clone.
 * @param {boolean} [isDeep] Specify a deep clone.
 * @returns {Buffer} Returns the cloned buffer.
 */
function cloneBuffer(buffer, isDeep) {
  if (isDeep) {
    return buffer.slice();
  }
  var length = buffer.length,
      result = allocUnsafe ? allocUnsafe(length) : new buffer.constructor(length);

  buffer.copy(result);
  return result;
}

/** Built-in value references. */
var Uint8Array$1 = root$1.Uint8Array;

var Uint8Array$2 = Uint8Array$1;

/**
 * Creates a clone of `arrayBuffer`.
 *
 * @private
 * @param {ArrayBuffer} arrayBuffer The array buffer to clone.
 * @returns {ArrayBuffer} Returns the cloned array buffer.
 */
function cloneArrayBuffer(arrayBuffer) {
  var result = new arrayBuffer.constructor(arrayBuffer.byteLength);
  new Uint8Array$2(result).set(new Uint8Array$2(arrayBuffer));
  return result;
}

/**
 * Creates a clone of `typedArray`.
 *
 * @private
 * @param {Object} typedArray The typed array to clone.
 * @param {boolean} [isDeep] Specify a deep clone.
 * @returns {Object} Returns the cloned typed array.
 */
function cloneTypedArray(typedArray, isDeep) {
  var buffer = isDeep ? cloneArrayBuffer(typedArray.buffer) : typedArray.buffer;
  return new typedArray.constructor(buffer, typedArray.byteOffset, typedArray.length);
}

/**
 * Initializes an object clone.
 *
 * @private
 * @param {Object} object The object to clone.
 * @returns {Object} Returns the initialized clone.
 */
function initCloneObject(object) {
  return (typeof object.constructor == 'function' && !isPrototype(object))
    ? baseCreate$1(getPrototype$1(object))
    : {};
}

/**
 * Creates a base function for methods like `_.forIn` and `_.forOwn`.
 *
 * @private
 * @param {boolean} [fromRight] Specify iterating from right to left.
 * @returns {Function} Returns the new base function.
 */
function createBaseFor(fromRight) {
  return function(object, iteratee, keysFunc) {
    var index = -1,
        iterable = Object(object),
        props = keysFunc(object),
        length = props.length;

    while (length--) {
      var key = props[fromRight ? length : ++index];
      if (iteratee(iterable[key], key, iterable) === false) {
        break;
      }
    }
    return object;
  };
}

/**
 * The base implementation of `baseForOwn` which iterates over `object`
 * properties returned by `keysFunc` and invokes `iteratee` for each property.
 * Iteratee functions may exit iteration early by explicitly returning `false`.
 *
 * @private
 * @param {Object} object The object to iterate over.
 * @param {Function} iteratee The function invoked per iteration.
 * @param {Function} keysFunc The function to get the keys of `object`.
 * @returns {Object} Returns `object`.
 */
var baseFor = createBaseFor();

var baseFor$1 = baseFor;

/**
 * Gets the timestamp of the number of milliseconds that have elapsed since
 * the Unix epoch (1 January 1970 00:00:00 UTC).
 *
 * @static
 * @memberOf _
 * @since 2.4.0
 * @category Date
 * @returns {number} Returns the timestamp.
 * @example
 *
 * _.defer(function(stamp) {
 *   console.log(_.now() - stamp);
 * }, _.now());
 * // => Logs the number of milliseconds it took for the deferred invocation.
 */
var now = function() {
  return root$1.Date.now();
};

var now$1 = now;

/** Error message constants. */
var FUNC_ERROR_TEXT$1 = 'Expected a function';

/* Built-in method references for those with the same name as other `lodash` methods. */
var nativeMax = Math.max,
    nativeMin = Math.min;

/**
 * Creates a debounced function that delays invoking `func` until after `wait`
 * milliseconds have elapsed since the last time the debounced function was
 * invoked. The debounced function comes with a `cancel` method to cancel
 * delayed `func` invocations and a `flush` method to immediately invoke them.
 * Provide `options` to indicate whether `func` should be invoked on the
 * leading and/or trailing edge of the `wait` timeout. The `func` is invoked
 * with the last arguments provided to the debounced function. Subsequent
 * calls to the debounced function return the result of the last `func`
 * invocation.
 *
 * **Note:** If `leading` and `trailing` options are `true`, `func` is
 * invoked on the trailing edge of the timeout only if the debounced function
 * is invoked more than once during the `wait` timeout.
 *
 * If `wait` is `0` and `leading` is `false`, `func` invocation is deferred
 * until to the next tick, similar to `setTimeout` with a timeout of `0`.
 *
 * See [David Corbacho's article](https://css-tricks.com/debouncing-throttling-explained-examples/)
 * for details over the differences between `_.debounce` and `_.throttle`.
 *
 * @static
 * @memberOf _
 * @since 0.1.0
 * @category Function
 * @param {Function} func The function to debounce.
 * @param {number} [wait=0] The number of milliseconds to delay.
 * @param {Object} [options={}] The options object.
 * @param {boolean} [options.leading=false]
 *  Specify invoking on the leading edge of the timeout.
 * @param {number} [options.maxWait]
 *  The maximum time `func` is allowed to be delayed before it's invoked.
 * @param {boolean} [options.trailing=true]
 *  Specify invoking on the trailing edge of the timeout.
 * @returns {Function} Returns the new debounced function.
 * @example
 *
 * // Avoid costly calculations while the window size is in flux.
 * jQuery(window).on('resize', _.debounce(calculateLayout, 150));
 *
 * // Invoke `sendMail` when clicked, debouncing subsequent calls.
 * jQuery(element).on('click', _.debounce(sendMail, 300, {
 *   'leading': true,
 *   'trailing': false
 * }));
 *
 * // Ensure `batchLog` is invoked once after 1 second of debounced calls.
 * var debounced = _.debounce(batchLog, 250, { 'maxWait': 1000 });
 * var source = new EventSource('/stream');
 * jQuery(source).on('message', debounced);
 *
 * // Cancel the trailing debounced invocation.
 * jQuery(window).on('popstate', debounced.cancel);
 */
function debounce(func, wait, options) {
  var lastArgs,
      lastThis,
      maxWait,
      result,
      timerId,
      lastCallTime,
      lastInvokeTime = 0,
      leading = false,
      maxing = false,
      trailing = true;

  if (typeof func != 'function') {
    throw new TypeError(FUNC_ERROR_TEXT$1);
  }
  wait = toNumber(wait) || 0;
  if (isObject$1(options)) {
    leading = !!options.leading;
    maxing = 'maxWait' in options;
    maxWait = maxing ? nativeMax(toNumber(options.maxWait) || 0, wait) : maxWait;
    trailing = 'trailing' in options ? !!options.trailing : trailing;
  }

  function invokeFunc(time) {
    var args = lastArgs,
        thisArg = lastThis;

    lastArgs = lastThis = undefined;
    lastInvokeTime = time;
    result = func.apply(thisArg, args);
    return result;
  }

  function leadingEdge(time) {
    // Reset any `maxWait` timer.
    lastInvokeTime = time;
    // Start the timer for the trailing edge.
    timerId = setTimeout(timerExpired, wait);
    // Invoke the leading edge.
    return leading ? invokeFunc(time) : result;
  }

  function remainingWait(time) {
    var timeSinceLastCall = time - lastCallTime,
        timeSinceLastInvoke = time - lastInvokeTime,
        timeWaiting = wait - timeSinceLastCall;

    return maxing
      ? nativeMin(timeWaiting, maxWait - timeSinceLastInvoke)
      : timeWaiting;
  }

  function shouldInvoke(time) {
    var timeSinceLastCall = time - lastCallTime,
        timeSinceLastInvoke = time - lastInvokeTime;

    // Either this is the first call, activity has stopped and we're at the
    // trailing edge, the system time has gone backwards and we're treating
    // it as the trailing edge, or we've hit the `maxWait` limit.
    return (lastCallTime === undefined || (timeSinceLastCall >= wait) ||
      (timeSinceLastCall < 0) || (maxing && timeSinceLastInvoke >= maxWait));
  }

  function timerExpired() {
    var time = now$1();
    if (shouldInvoke(time)) {
      return trailingEdge(time);
    }
    // Restart the timer.
    timerId = setTimeout(timerExpired, remainingWait(time));
  }

  function trailingEdge(time) {
    timerId = undefined;

    // Only invoke if we have `lastArgs` which means `func` has been
    // debounced at least once.
    if (trailing && lastArgs) {
      return invokeFunc(time);
    }
    lastArgs = lastThis = undefined;
    return result;
  }

  function cancel() {
    if (timerId !== undefined) {
      clearTimeout(timerId);
    }
    lastInvokeTime = 0;
    lastArgs = lastCallTime = lastThis = timerId = undefined;
  }

  function flush() {
    return timerId === undefined ? result : trailingEdge(now$1());
  }

  function debounced() {
    var time = now$1(),
        isInvoking = shouldInvoke(time);

    lastArgs = arguments;
    lastThis = this;
    lastCallTime = time;

    if (isInvoking) {
      if (timerId === undefined) {
        return leadingEdge(lastCallTime);
      }
      if (maxing) {
        // Handle invocations in a tight loop.
        clearTimeout(timerId);
        timerId = setTimeout(timerExpired, wait);
        return invokeFunc(lastCallTime);
      }
    }
    if (timerId === undefined) {
      timerId = setTimeout(timerExpired, wait);
    }
    return result;
  }
  debounced.cancel = cancel;
  debounced.flush = flush;
  return debounced;
}

/**
 * This function is like `assignValue` except that it doesn't assign
 * `undefined` values.
 *
 * @private
 * @param {Object} object The object to modify.
 * @param {string} key The key of the property to assign.
 * @param {*} value The value to assign.
 */
function assignMergeValue(object, key, value) {
  if ((value !== undefined && !eq(object[key], value)) ||
      (value === undefined && !(key in object))) {
    baseAssignValue(object, key, value);
  }
}

/**
 * This method is like `_.isArrayLike` except that it also checks if `value`
 * is an object.
 *
 * @static
 * @memberOf _
 * @since 4.0.0
 * @category Lang
 * @param {*} value The value to check.
 * @returns {boolean} Returns `true` if `value` is an array-like object,
 *  else `false`.
 * @example
 *
 * _.isArrayLikeObject([1, 2, 3]);
 * // => true
 *
 * _.isArrayLikeObject(document.body.children);
 * // => true
 *
 * _.isArrayLikeObject('abc');
 * // => false
 *
 * _.isArrayLikeObject(_.noop);
 * // => false
 */
function isArrayLikeObject(value) {
  return isObjectLike(value) && isArrayLike(value);
}

/**
 * Gets the value at `key`, unless `key` is "__proto__" or "constructor".
 *
 * @private
 * @param {Object} object The object to query.
 * @param {string} key The key of the property to get.
 * @returns {*} Returns the property value.
 */
function safeGet(object, key) {
  if (key === 'constructor' && typeof object[key] === 'function') {
    return;
  }

  if (key == '__proto__') {
    return;
  }

  return object[key];
}

/**
 * Converts `value` to a plain object flattening inherited enumerable string
 * keyed properties of `value` to own properties of the plain object.
 *
 * @static
 * @memberOf _
 * @since 3.0.0
 * @category Lang
 * @param {*} value The value to convert.
 * @returns {Object} Returns the converted plain object.
 * @example
 *
 * function Foo() {
 *   this.b = 2;
 * }
 *
 * Foo.prototype.c = 3;
 *
 * _.assign({ 'a': 1 }, new Foo);
 * // => { 'a': 1, 'b': 2 }
 *
 * _.assign({ 'a': 1 }, _.toPlainObject(new Foo));
 * // => { 'a': 1, 'b': 2, 'c': 3 }
 */
function toPlainObject(value) {
  return copyObject(value, keysIn(value));
}

/**
 * A specialized version of `baseMerge` for arrays and objects which performs
 * deep merges and tracks traversed objects enabling objects with circular
 * references to be merged.
 *
 * @private
 * @param {Object} object The destination object.
 * @param {Object} source The source object.
 * @param {string} key The key of the value to merge.
 * @param {number} srcIndex The index of `source`.
 * @param {Function} mergeFunc The function to merge values.
 * @param {Function} [customizer] The function to customize assigned values.
 * @param {Object} [stack] Tracks traversed source values and their merged
 *  counterparts.
 */
function baseMergeDeep(object, source, key, srcIndex, mergeFunc, customizer, stack) {
  var objValue = safeGet(object, key),
      srcValue = safeGet(source, key),
      stacked = stack.get(srcValue);

  if (stacked) {
    assignMergeValue(object, key, stacked);
    return;
  }
  var newValue = customizer
    ? customizer(objValue, srcValue, (key + ''), object, source, stack)
    : undefined;

  var isCommon = newValue === undefined;

  if (isCommon) {
    var isArr = isArray$2(srcValue),
        isBuff = !isArr && isBuffer$1(srcValue),
        isTyped = !isArr && !isBuff && isTypedArray$1(srcValue);

    newValue = srcValue;
    if (isArr || isBuff || isTyped) {
      if (isArray$2(objValue)) {
        newValue = objValue;
      }
      else if (isArrayLikeObject(objValue)) {
        newValue = copyArray(objValue);
      }
      else if (isBuff) {
        isCommon = false;
        newValue = cloneBuffer(srcValue, true);
      }
      else if (isTyped) {
        isCommon = false;
        newValue = cloneTypedArray(srcValue, true);
      }
      else {
        newValue = [];
      }
    }
    else if (isPlainObject(srcValue) || isArguments$1(srcValue)) {
      newValue = objValue;
      if (isArguments$1(objValue)) {
        newValue = toPlainObject(objValue);
      }
      else if (!isObject$1(objValue) || isFunction$1(objValue)) {
        newValue = initCloneObject(srcValue);
      }
    }
    else {
      isCommon = false;
    }
  }
  if (isCommon) {
    // Recursively merge objects and arrays (susceptible to call stack limits).
    stack.set(srcValue, newValue);
    mergeFunc(newValue, srcValue, srcIndex, customizer, stack);
    stack['delete'](srcValue);
  }
  assignMergeValue(object, key, newValue);
}

/**
 * The base implementation of `_.merge` without support for multiple sources.
 *
 * @private
 * @param {Object} object The destination object.
 * @param {Object} source The source object.
 * @param {number} srcIndex The index of `source`.
 * @param {Function} [customizer] The function to customize merged values.
 * @param {Object} [stack] Tracks traversed source values and their merged
 *  counterparts.
 */
function baseMerge(object, source, srcIndex, customizer, stack) {
  if (object === source) {
    return;
  }
  baseFor$1(source, function(srcValue, key) {
    stack || (stack = new Stack);
    if (isObject$1(srcValue)) {
      baseMergeDeep(object, source, key, srcIndex, baseMerge, customizer, stack);
    }
    else {
      var newValue = customizer
        ? customizer(safeGet(object, key), srcValue, (key + ''), object, source, stack)
        : undefined;

      if (newValue === undefined) {
        newValue = srcValue;
      }
      assignMergeValue(object, key, newValue);
    }
  }, keysIn);
}

/**
 * This method is like `_.assign` except that it recursively merges own and
 * inherited enumerable string keyed properties of source objects into the
 * destination object. Source properties that resolve to `undefined` are
 * skipped if a destination value exists. Array and plain object properties
 * are merged recursively. Other objects and value types are overridden by
 * assignment. Source objects are applied from left to right. Subsequent
 * sources overwrite property assignments of previous sources.
 *
 * **Note:** This method mutates `object`.
 *
 * @static
 * @memberOf _
 * @since 0.5.0
 * @category Object
 * @param {Object} object The destination object.
 * @param {...Object} [sources] The source objects.
 * @returns {Object} Returns `object`.
 * @example
 *
 * var object = {
 *   'a': [{ 'b': 2 }, { 'd': 4 }]
 * };
 *
 * var other = {
 *   'a': [{ 'c': 3 }, { 'e': 5 }]
 * };
 *
 * _.merge(object, other);
 * // => { 'a': [{ 'b': 2, 'c': 3 }, { 'd': 4, 'e': 5 }] }
 */
var merge = createAssigner(function(object, source, srcIndex) {
  baseMerge(object, source, srcIndex);
});

var merge$1 = merge;

/** Error message constants. */
var FUNC_ERROR_TEXT = 'Expected a function';

/**
 * Creates a throttled function that only invokes `func` at most once per
 * every `wait` milliseconds. The throttled function comes with a `cancel`
 * method to cancel delayed `func` invocations and a `flush` method to
 * immediately invoke them. Provide `options` to indicate whether `func`
 * should be invoked on the leading and/or trailing edge of the `wait`
 * timeout. The `func` is invoked with the last arguments provided to the
 * throttled function. Subsequent calls to the throttled function return the
 * result of the last `func` invocation.
 *
 * **Note:** If `leading` and `trailing` options are `true`, `func` is
 * invoked on the trailing edge of the timeout only if the throttled function
 * is invoked more than once during the `wait` timeout.
 *
 * If `wait` is `0` and `leading` is `false`, `func` invocation is deferred
 * until to the next tick, similar to `setTimeout` with a timeout of `0`.
 *
 * See [David Corbacho's article](https://css-tricks.com/debouncing-throttling-explained-examples/)
 * for details over the differences between `_.throttle` and `_.debounce`.
 *
 * @static
 * @memberOf _
 * @since 0.1.0
 * @category Function
 * @param {Function} func The function to throttle.
 * @param {number} [wait=0] The number of milliseconds to throttle invocations to.
 * @param {Object} [options={}] The options object.
 * @param {boolean} [options.leading=true]
 *  Specify invoking on the leading edge of the timeout.
 * @param {boolean} [options.trailing=true]
 *  Specify invoking on the trailing edge of the timeout.
 * @returns {Function} Returns the new throttled function.
 * @example
 *
 * // Avoid excessively updating the position while scrolling.
 * jQuery(window).on('scroll', _.throttle(updatePosition, 100));
 *
 * // Invoke `renewToken` when the click event is fired, but not more than once every 5 minutes.
 * var throttled = _.throttle(renewToken, 300000, { 'trailing': false });
 * jQuery(element).on('click', throttled);
 *
 * // Cancel the trailing throttled invocation.
 * jQuery(window).on('popstate', throttled.cancel);
 */
function throttle(func, wait, options) {
  var leading = true,
      trailing = true;

  if (typeof func != 'function') {
    throw new TypeError(FUNC_ERROR_TEXT);
  }
  if (isObject$1(options)) {
    leading = 'leading' in options ? !!options.leading : leading;
    trailing = 'trailing' in options ? !!options.trailing : trailing;
  }
  return debounce(func, wait, {
    'leading': leading,
    'maxWait': wait,
    'trailing': trailing
  });
}

/**
 * 射线拾取
 */
const getIntersects = ({ event, $map, scene, camera, objects }) => {
    const { top, left } = $map.getBoundingClientRect();
    // 声明raycaster和mouse变量
    const raycaster = new Raycaster();
    const mouse = new Vector2();
    // 通过鼠标点击的位置计算出raycaster所需要的点的位置，以屏幕中心为原点，值的范围为-1到1.
    mouse.x = ((event.clientX - left) / $map.clientWidth) * 2 - 1;
    mouse.y = -((event.clientY - top) / $map.clientHeight) * 2 + 1;
    // 通过鼠标点的位置和当前相机的矩阵计算出raycaster
    raycaster.setFromCamera(mouse, camera);
    // 获取raycaster直线和所有模型相交的数组集合，注意：true表示返回的值会递归，找到更深层次的模型
    const intersects = raycaster.intersectObjects(objects || scene.children, true);
    // 2d 场景下会存在bug，就是选择点的时候，跑到中心点去了，数组第一个是对象 AxesHelper 导致的，这里进行过滤
    // intersects = intersects.filter(item => !(item.object instanceof AxesHelper))
    // if (filter) {
    //   intersects = filter(intersects)
    // }
    return intersects;
};
/**
 * 获取世界坐标
 * 用于射线拾取对象
 * objects 传入需要被射线拾取的物体。精准判断情况，不传入 objects， 获取被射线拾取的所有对象，然后再判断第一个对象是否被命中，即可判断当前是否点击了想要的对象。
 * @return 返回第一个点和所有被射线拾取的对象
 */
const getWorldPosition = ({ event, $map, scene, camera, objects }) => {
    const intersects = getIntersects({ event, $map, scene, camera, objects });
    const points = intersects.map(item => item.point);
    const worldPosition = new Vector3();
    if (points.length > 0) {
        worldPosition.set(points[0].x, points[0].y, points[0].z);
        return { worldPosition, intersects };
    }
    return {};
};
/**
 * 获取屏幕坐标
 */
const getScreenPostion = ({ worldPosition, $map, scene, camera }) => {
    const { top, left, width, height } = $map.getBoundingClientRect();
    const standardVector = new Vector3().copy(worldPosition).project(camera);
    const halfWidth = width / 2;
    const halfHeight = height / 2;
    const x = Math.round(standardVector.x * halfWidth + halfWidth);
    const y = Math.round(-standardVector.y * halfHeight + halfHeight);
    return {
        x: x + left,
        y: y + top
    };
};
/**
 * 根据 name 获取对应的对象集合
 */
const getObjectsByName = (name, parent) => {
    // ❌ 方法1
    // scene.getObjectByName 只会返回第一个
    // return scene.getObjectByName(name);
    // ❌ 方法2
    // 不能深层遍历
    // return scene.children.filter(item => item.name === name);
    // ✅ 较优算法
    const arr = [];
    parent.traverse(item => {
        if (item.name === name)
            arr.push(item);
    });
    return arr;
};
/**
 * 根据 name 获取对应的对象
 */
const getObjectByName = (name, parent) => {
    return getObjectsByName(name, parent)[0];
};
const getPointBetweenPoints = ({ p1, p2, 
// +1 把终点加入
segment = Math.abs(Math.sqrt(Math.pow(p1.x - p2.x, 2) + Math.pow(p1.y - p2.y, 2))) + 1, 
// 从 0 开始，把起点加入
i = 0 }) => {
    return {
        point: new Vector2(((p2.x - p1.x) / segment) * i + p1.x, ((p2.y - p1.y) / segment) * i + p1.y),
        segment
    };
};
/**
 * 计算两个坐标连线后的倾斜角度
 */
const getAngle = (p1, p2) => {
    const radian = Math.atan2(p2.y - p1.y, p2.x - p1.x);
    const angle = radian * (180 / Math.PI);
    return {
        radian,
        angle
    };
};
const CLS_PREFIX = 'ktmap';
/**
 * 截取精度
 */
const truncateBase = (n, precision = 3) => {
    if (isNaN(+n))
        return n;
    return parseFloat((+n).toFixed(precision));
};
const truncateNumber = (data, precision = 3) => {
    return (Array.isArray(data)
        ? data.map(_ => truncateBase(_, precision))
        : truncateBase(data, precision));
};
const truncateVector2 = (data, precision = 3) => {
    return (Array.isArray(data)
        ? data.map(_ => new Vector2(truncateBase(_.x, precision), truncateBase(_.y, precision)))
        : new Vector2(truncateBase(data.x, precision), truncateBase(data.y, precision)));
};
const truncateVector3 = (data, precision = 3) => {
    return (Array.isArray(data)
        ? data.map(_ => new Vector3(truncateBase(_.x, precision), truncateBase(_.y, precision), truncateBase(_.z, precision)))
        : new Vector3(truncateBase(data.x, precision), truncateBase(data.y, precision), truncateBase(data.z, precision)));
};
/**
 * 获取两点间距离
 */
const getDistance = (p1, p2) => {
    return Math.abs(Math.sqrt(Math.pow(p1.x - p2.x, 2) + Math.pow(p1.y - p2.y, 2)));
};
/**
 * 获取包围盒的中心点
 */
const getBox3Center = (mesh) => {
    return new Box3().setFromObject(mesh).getCenter(new Vector3());
};
/**
 * sleep
 */
const sleep = (delay = 1000) => new Promise(_ => setTimeout(_, delay));
const getDollys = (targetMesh, controls, offset = 5) => {
    if (!targetMesh) {
        return { fitDistance: 0, dollys: [0] };
    }
    const bb = new Box3().setFromObject(targetMesh);
    const fitDistance = controls.getDistanceToFitBox(bb.max.x - bb.min.x, bb.max.y - bb.min.y, bb.max.z - bb.min.z);
    const minDollys = [...new Array(offset)]
        .map((_, i) => fitDistance / (i + 2))
        .reverse();
    const maxDollys = [...new Array(offset)].map((_, i) => fitDistance * (i + 2));
    const dollys = [...minDollys, fitDistance, ...maxDollys];
    return { fitDistance, dollys };
};
const NOOP = () => { };
const extend = Object.assign;
const objectToString = Object.prototype.toString;
const toTypeString = (value) => objectToString.call(value);
// is
const isArray = Array.isArray;
const isMap = (val) => toTypeString(val) === '[object Map]';
const isSet = (val) => toTypeString(val) === '[object Set]';
const isDate = (val) => toTypeString(val) === '[object Date]';
const isFunction = (val) => typeof val === 'function';
const isString = (val) => typeof val === 'string';
const isSymbol = (val) => typeof val === 'symbol';
const isObject = (val) => val !== null && typeof val === 'object';
const isPromise = (val) => {
    return isObject(val) && isFunction(val.then) && isFunction(val.catch);
};

export { AStar, CLS_PREFIX, GLTFLoaderPromise, NOOP, debounce, extend, getAngle, getBox3Center, getDistance, getDollys, getIntersects, getObjectByName, getObjectsByName, getPointBetweenPoints, getScreenPostion, getWorldPosition, isArray, isDate, isFunction, isMap, isObject, isPromise, isSet, isString, isSymbol, merge$1 as merge, objectToString, sleep, throttle, toTypeString, truncateNumber, truncateVector2, truncateVector3, warn };
