/**
 * @author Rich Tibbett / https://github.com/richtr
 * @author mrdoob / http://mrdoob.com/
 * @author Tony Parisi / http://www.tonyparisi.com/
 * @author Takahiro / https://github.com/takahirox
 * @author Don McCurdy / https://www.donmccurdy.com
 */

THREE.GLTFLoader = (function () {

    function GLTFLoader(manager) {

        this.manager = (manager !== undefined) ? manager : THREE.DefaultLoadingManager;
        this.dracoLoader = null;

    }

    GLTFLoader.prototype = {

        constructor: GLTFLoader,

        crossOrigin: 'Anonymous',

        load: function (url, onLoad, onProgress, onError) {

            var scope = this;

            var path = this.path !== undefined ? this.path : THREE.LoaderUtils.extractUrlBase(url);

            var loader = new THREE.FileLoader(scope.manager);

            loader.setResponseType('arraybuffer');

            loader.load(url, function (data) {

                try {

                    scope.parse(data, path, onLoad, onError);

                } catch (e) {

                    if (onError !== undefined) {

                        onError(e);

                    } else {

                        throw e;

                    }

                }

            }, onProgress, onError);

        },

        setCrossOrigin: function (value) {

            this.crossOrigin = value;
            return this;

        },

        setPath: function (value) {

            this.path = value;
            return this;

        },

        setDRACOLoader: function (dracoLoader) {

            this.dracoLoader = dracoLoader;
            return this;

        },

        parse: function (data, path, onLoad, onError) {

            var content;
            var extensions = {};

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

                content = data;

            } else {

                var magic = THREE.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 = THREE.LoaderUtils.decodeText(new Uint8Array(data));

                }

            }

            var 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. Use LegacyGLTFLoader instead.'));
                return;

            }

            if (json.extensionsUsed) {

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

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

                    switch (extensionName) {

                        case EXTENSIONS.KHR_LIGHTS:
                            extensions[extensionName] = new GLTFLightsExtension(json);
                            break;

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

                        default:

                            if (extensionsRequired.indexOf(extensionName) >= 0) {

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

                            }

                    }

                }

            }

            var parser = new GLTFParser(json, extensions, {

                path: path || this.path || '',
                crossOrigin: this.crossOrigin,
                manager: this.manager

            });

            parser.parse(function (scene, scenes, cameras, animations, json) {

                var glTF = {
                    scene: scene,
                    scenes: scenes,
                    cameras: cameras,
                    animations: animations,
                    asset: json.asset,
                    parser: parser,
                    userData: {}
                };

                addUnknownExtensionsToUserData(extensions, glTF, json);

                onLoad(glTF);

            }, onError);

        }

    };

    /* GLTFREGISTRY */

    function GLTFRegistry() {

        var 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 ***********/
    /*********************************/

    var EXTENSIONS = {
        KHR_BINARY_GLTF: 'KHR_binary_glTF',
        KHR_DRACO_MESH_COMPRESSION: 'KHR_draco_mesh_compression',
        KHR_LIGHTS: 'KHR_lights',
        KHR_MATERIALS_PBR_SPECULAR_GLOSSINESS: 'KHR_materials_pbrSpecularGlossiness',
        KHR_MATERIALS_UNLIT: 'KHR_materials_unlit',
        MSFT_TEXTURE_DDS: 'MSFT_texture_dds'
    };

    /**
	 * DDS Texture Extension
	 *
	 * Specification: 
	 * https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Vendor/MSFT_texture_dds
	 * 
	 */
    function GLTFTextureDDSExtension() {

        if (!THREE.DDSLoader) {

            throw new Error('THREE.GLTFLoader: Attempting to load .dds texture without importing THREE.DDSLoader');

        }

        this.name = EXTENSIONS.MSFT_TEXTURE_DDS;
        this.ddsLoader = new THREE.DDSLoader();

    }

    /**
	 * Lights Extension
	 *
	 * Specification: PENDING
	 */
    function GLTFLightsExtension(json) {

        this.name = EXTENSIONS.KHR_LIGHTS;

        this.lights = {};

        var extension = (json.extensions && json.extensions[EXTENSIONS.KHR_LIGHTS]) || {};
        var lights = extension.lights || {};

        for (var lightId in lights) {

            var light = lights[lightId];
            var lightNode;

            var color = new THREE.Color().fromArray(light.color);

            switch (light.type) {

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

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

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

                case 'ambient':
                    lightNode = new THREE.AmbientLight(color);
                    break;

            }

            if (lightNode) {

                lightNode.decay = 2;

                if (light.intensity !== undefined) {

                    lightNode.intensity = light.intensity;

                }

                lightNode.name = light.name || ('light_' + lightId);
                this.lights[lightId] = lightNode;

            }

        }

    }

    /**
	 * Unlit Materials Extension (pending)
	 *
	 * PR: https://github.com/KhronosGroup/glTF/pull/1163
	 */
    function GLTFMaterialsUnlitExtension(json) {

        this.name = EXTENSIONS.KHR_MATERIALS_UNLIT;

    }

    GLTFMaterialsUnlitExtension.prototype.getMaterialType = function (material) {

        return THREE.MeshBasicMaterial;

    };

    GLTFMaterialsUnlitExtension.prototype.extendParams = function (materialParams, material, parser) {

        var pending = [];

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

        var metallicRoughness = material.pbrMetallicRoughness;

        if (metallicRoughness) {

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

                var array = metallicRoughness.baseColorFactor;

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

            }

            if (metallicRoughness.baseColorTexture !== undefined) {

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

            }

        }

        return Promise.all(pending);

    };

    /* BINARY EXTENSION */

    var BINARY_EXTENSION_BUFFER_NAME = 'binary_glTF';
    var BINARY_EXTENSION_HEADER_MAGIC = 'glTF';
    var BINARY_EXTENSION_HEADER_LENGTH = 12;
    var BINARY_EXTENSION_CHUNK_TYPES = { JSON: 0x4E4F534A, BIN: 0x004E4942 };

    function GLTFBinaryExtension(data) {

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

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

        this.header = {
            magic: THREE.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. Use LegacyGLTFLoader instead.');

        }

        var chunkView = new DataView(data, BINARY_EXTENSION_HEADER_LENGTH);
        var chunkIndex = 0;

        while (chunkIndex < chunkView.byteLength) {

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

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

            if (chunkType === BINARY_EXTENSION_CHUNK_TYPES.JSON) {

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

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

                var 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/pull/874
	 */
    function GLTFDracoMeshCompressionExtension(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;

    }

    GLTFDracoMeshCompressionExtension.prototype.decodePrimitive = function (primitive, parser) {

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

        for (var attributeName in gltfAttributeMap) {

            if (!(attributeName in ATTRIBUTES)) continue;

            threeAttributeMap[ATTRIBUTES[attributeName]] = gltfAttributeMap[attributeName];

        }

        for (attributeName in primitive.attributes) {

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

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

                attributeTypeMap[ATTRIBUTES[attributeName]] = componentType;
                attributeNormalizedMap[ATTRIBUTES[attributeName]] = accessorDef.normalized === true;

            }

        }

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

            return new Promise(function (resolve) {

                dracoLoader.decodeDracoFile(bufferView, function (geometry) {

                    for (var attributeName in geometry.attributes) {

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

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

                    }

                    resolve(geometry);

                }, threeAttributeMap, attributeTypeMap);

            });

        });

    };

    /**
	 * Specular-Glossiness Extension
	 *
	 * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_materials_pbrSpecularGlossiness
	 */
    function GLTFMaterialsPbrSpecularGlossinessExtension() {

        return {

            name: EXTENSIONS.KHR_MATERIALS_PBR_SPECULAR_GLOSSINESS,

            specularGlossinessParams: [
				'color',
				'map',
				'lightMap',
				'lightMapIntensity',
				'aoMap',
				'aoMapIntensity',
				'emissive',
				'emissiveIntensity',
				'emissiveMap',
				'bumpMap',
				'bumpScale',
				'normalMap',
				'displacementMap',
				'displacementScale',
				'displacementBias',
				'specularMap',
				'specular',
				'glossinessMap',
				'glossiness',
				'alphaMap',
				'envMap',
				'envMapIntensity',
				'refractionRatio',
            ],

            getMaterialType: function () {

                return THREE.ShaderMaterial;

            },

            extendParams: function (params, material, parser) {

                var pbrSpecularGlossiness = material.extensions[this.name];

                var shader = THREE.ShaderLib['standard'];

                var uniforms = THREE.UniformsUtils.clone(shader.uniforms);

                var specularMapParsFragmentChunk = [
					'#ifdef USE_SPECULARMAP',
					'	uniform sampler2D specularMap;',
					'#endif'
                ].join('\n');

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

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

                var 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');

                var lightPhysicalFragmentChunk = [
					'PhysicalMaterial material;',
					'material.diffuseColor = diffuseColor.rgb;',
					'material.specularRoughness = clamp( 1.0 - glossinessFactor, 0.04, 1.0 );',
					'material.specularColor = specularFactor.rgb;',
                ].join('\n');

                var 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);

                delete uniforms.roughness;
                delete uniforms.metalness;
                delete uniforms.roughnessMap;
                delete uniforms.metalnessMap;

                uniforms.specular = { value: new THREE.Color().setHex(0x111111) };
                uniforms.glossiness = { value: 0.5 };
                uniforms.specularMap = { value: null };
                uniforms.glossinessMap = { value: null };

                params.vertexShader = shader.vertexShader;
                params.fragmentShader = fragmentShader;
                params.uniforms = uniforms;
                params.defines = { 'STANDARD': '' };

                params.color = new THREE.Color(1.0, 1.0, 1.0);
                params.opacity = 1.0;

                var pending = [];

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

                    var array = pbrSpecularGlossiness.diffuseFactor;

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

                }

                if (pbrSpecularGlossiness.diffuseTexture !== undefined) {

                    pending.push(parser.assignTexture(params, 'map', pbrSpecularGlossiness.diffuseTexture.index));

                }

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

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

                    params.specular.fromArray(pbrSpecularGlossiness.specularFactor);

                }

                if (pbrSpecularGlossiness.specularGlossinessTexture !== undefined) {

                    var specGlossIndex = pbrSpecularGlossiness.specularGlossinessTexture.index;
                    pending.push(parser.assignTexture(params, 'glossinessMap', specGlossIndex));
                    pending.push(parser.assignTexture(params, 'specularMap', specGlossIndex));

                }

                return Promise.all(pending);

            },

            createMaterial: function (params) {

                // setup material properties based on MeshStandardMaterial for Specular-Glossiness

                var material = new THREE.ShaderMaterial({
                    defines: params.defines,
                    vertexShader: params.vertexShader,
                    fragmentShader: params.fragmentShader,
                    uniforms: params.uniforms,
                    fog: true,
                    lights: true,
                    opacity: params.opacity,
                    transparent: params.transparent
                });

                material.isGLTFSpecularGlossinessMaterial = true;

                material.color = params.color;

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

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

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

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

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

                material.normalMap = params.normalMap === undefined ? null : params.normalMap;
                if (params.normalScale) material.normalScale = params.normalScale;

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

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

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

                material.alphaMap = null;

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

                material.refractionRatio = 0.98;

                material.extensions.derivatives = true;

                return material;

            },

            /**
			 * Clones a GLTFSpecularGlossinessMaterial instance. The ShaderMaterial.copy() method can
			 * copy only properties it knows about or inherits, and misses many properties that would
			 * normally be defined by MeshStandardMaterial.
			 *
			 * This method allows GLTFSpecularGlossinessMaterials to be cloned in the process of
			 * loading a glTF model, but cloning later (e.g. by the user) would require these changes
			 * AND also updating `.onBeforeRender` on the parent mesh.
			 *
			 * @param  {THREE.ShaderMaterial} source
			 * @return {THREE.ShaderMaterial}
			 */
            cloneMaterial: function (source) {

                var target = source.clone();

                target.isGLTFSpecularGlossinessMaterial = true;

                var params = this.specularGlossinessParams;

                for (var i = 0, il = params.length; i < il; i++) {

                    target[params[i]] = source[params[i]];

                }

                return target;

            },

            // Here's based on refreshUniformsCommon() and refreshUniformsStandard() in WebGLRenderer.
            refreshUniforms: function (renderer, scene, camera, geometry, material, group) {

                if (material.isGLTFSpecularGlossinessMaterial !== true) {

                    return;

                }

                var uniforms = material.uniforms;
                var defines = material.defines;

                uniforms.opacity.value = material.opacity;

                uniforms.diffuse.value.copy(material.color);
                uniforms.emissive.value.copy(material.emissive).multiplyScalar(material.emissiveIntensity);

                uniforms.map.value = material.map;
                uniforms.specularMap.value = material.specularMap;
                uniforms.alphaMap.value = material.alphaMap;

                uniforms.lightMap.value = material.lightMap;
                uniforms.lightMapIntensity.value = material.lightMapIntensity;

                uniforms.aoMap.value = material.aoMap;
                uniforms.aoMapIntensity.value = material.aoMapIntensity;

                // uv repeat and offset setting priorities
                // 1. color map
                // 2. specular map
                // 3. normal map
                // 4. bump map
                // 5. alpha map
                // 6. emissive map

                var uvScaleMap;

                if (material.map) {

                    uvScaleMap = material.map;

                } else if (material.specularMap) {

                    uvScaleMap = material.specularMap;

                } else if (material.displacementMap) {

                    uvScaleMap = material.displacementMap;

                } else if (material.normalMap) {

                    uvScaleMap = material.normalMap;

                } else if (material.bumpMap) {

                    uvScaleMap = material.bumpMap;

                } else if (material.glossinessMap) {

                    uvScaleMap = material.glossinessMap;

                } else if (material.alphaMap) {

                    uvScaleMap = material.alphaMap;

                } else if (material.emissiveMap) {

                    uvScaleMap = material.emissiveMap;

                }

                if (uvScaleMap !== undefined) {

                    // backwards compatibility
                    if (uvScaleMap.isWebGLRenderTarget) {

                        uvScaleMap = uvScaleMap.texture;

                    }

                    var offset;
                    var repeat;

                    if (uvScaleMap.matrix !== undefined) {

                        // > r88.

                        if (uvScaleMap.matrixAutoUpdate === true) {

                            offset = uvScaleMap.offset;
                            repeat = uvScaleMap.repeat;
                            var rotation = uvScaleMap.rotation;
                            var center = uvScaleMap.center;

                            uvScaleMap.matrix.setUvTransform(offset.x, offset.y, repeat.x, repeat.y, rotation, center.x, center.y);

                        }

                        uniforms.uvTransform.value.copy(uvScaleMap.matrix);

                    } else {

                        // <= r87. Remove when reasonable.

                        offset = uvScaleMap.offset;
                        repeat = uvScaleMap.repeat;

                        uniforms.offsetRepeat.value.set(offset.x, offset.y, repeat.x, repeat.y);

                    }

                }

                uniforms.envMap.value = material.envMap;
                uniforms.envMapIntensity.value = material.envMapIntensity;
                uniforms.flipEnvMap.value = (material.envMap && material.envMap.isCubeTexture) ? -1 : 1;

                uniforms.refractionRatio.value = material.refractionRatio;

                uniforms.specular.value.copy(material.specular);
                uniforms.glossiness.value = material.glossiness;

                uniforms.glossinessMap.value = material.glossinessMap;

                uniforms.emissiveMap.value = material.emissiveMap;
                uniforms.bumpMap.value = material.bumpMap;
                uniforms.normalMap.value = material.normalMap;

                uniforms.displacementMap.value = material.displacementMap;
                uniforms.displacementScale.value = material.displacementScale;
                uniforms.displacementBias.value = material.displacementBias;

                if (uniforms.glossinessMap.value !== null && defines.USE_GLOSSINESSMAP === undefined) {

                    defines.USE_GLOSSINESSMAP = '';
                    // set USE_ROUGHNESSMAP to enable vUv
                    defines.USE_ROUGHNESSMAP = '';

                }

                if (uniforms.glossinessMap.value === null && defines.USE_GLOSSINESSMAP !== undefined) {

                    delete defines.USE_GLOSSINESSMAP;
                    delete defines.USE_ROUGHNESSMAP;

                }

            }

        };

    }

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

    // Spline Interpolation
    // Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#appendix-c-spline-interpolation
    function GLTFCubicSplineInterpolant(parameterPositions, sampleValues, sampleSize, resultBuffer) {

        THREE.Interpolant.call(this, parameterPositions, sampleValues, sampleSize, resultBuffer);

    };

    GLTFCubicSplineInterpolant.prototype = Object.create(THREE.Interpolant.prototype);
    GLTFCubicSplineInterpolant.prototype.constructor = GLTFCubicSplineInterpolant;

    GLTFCubicSplineInterpolant.prototype.interpolate_ = function (i1, t0, t, t1) {

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

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

        var td = t1 - t0;

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

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

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

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

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

    };

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

    /* CONSTANTS */

    var 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
    };

    var WEBGL_TYPE = {
        5126: Number,
        //35674: THREE.Matrix2,
        35675: THREE.Matrix3,
        35676: THREE.Matrix4,
        35664: THREE.Vector2,
        35665: THREE.Vector3,
        35666: THREE.Vector4,
        35678: THREE.Texture
    };

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

    var WEBGL_FILTERS = {
        9728: THREE.NearestFilter,
        9729: THREE.LinearFilter,
        9984: THREE.NearestMipMapNearestFilter,
        9985: THREE.LinearMipMapNearestFilter,
        9986: THREE.NearestMipMapLinearFilter,
        9987: THREE.LinearMipMapLinearFilter
    };

    var WEBGL_WRAPPINGS = {
        33071: THREE.ClampToEdgeWrapping,
        33648: THREE.MirroredRepeatWrapping,
        10497: THREE.RepeatWrapping
    };

    var WEBGL_TEXTURE_FORMATS = {
        6406: THREE.AlphaFormat,
        6407: THREE.RGBFormat,
        6408: THREE.RGBAFormat,
        6409: THREE.LuminanceFormat,
        6410: THREE.LuminanceAlphaFormat
    };

    var WEBGL_TEXTURE_DATATYPES = {
        5121: THREE.UnsignedByteType,
        32819: THREE.UnsignedShort4444Type,
        32820: THREE.UnsignedShort5551Type,
        33635: THREE.UnsignedShort565Type
    };

    var WEBGL_SIDES = {
        1028: THREE.BackSide, // Culling front
        1029: THREE.FrontSide // Culling back
        //1032: THREE.NoSide   // Culling front and back, what to do?
    };

    var WEBGL_DEPTH_FUNCS = {
        512: THREE.NeverDepth,
        513: THREE.LessDepth,
        514: THREE.EqualDepth,
        515: THREE.LessEqualDepth,
        516: THREE.GreaterEqualDepth,
        517: THREE.NotEqualDepth,
        518: THREE.GreaterEqualDepth,
        519: THREE.AlwaysDepth
    };

    var WEBGL_BLEND_EQUATIONS = {
        32774: THREE.AddEquation,
        32778: THREE.SubtractEquation,
        32779: THREE.ReverseSubtractEquation
    };

    var WEBGL_BLEND_FUNCS = {
        0: THREE.ZeroFactor,
        1: THREE.OneFactor,
        768: THREE.SrcColorFactor,
        769: THREE.OneMinusSrcColorFactor,
        770: THREE.SrcAlphaFactor,
        771: THREE.OneMinusSrcAlphaFactor,
        772: THREE.DstAlphaFactor,
        773: THREE.OneMinusDstAlphaFactor,
        774: THREE.DstColorFactor,
        775: THREE.OneMinusDstColorFactor,
        776: THREE.SrcAlphaSaturateFactor
        // The followings are not supported by Three.js yet
        //32769: CONSTANT_COLOR,
        //32770: ONE_MINUS_CONSTANT_COLOR,
        //32771: CONSTANT_ALPHA,
        //32772: ONE_MINUS_CONSTANT_COLOR
    };

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

    var ATTRIBUTES = {
        POSITION: 'position',
        NORMAL: 'normal',
        TEXCOORD_0: 'uv',
        TEXCOORD0: 'uv', // deprecated
        TEXCOORD: 'uv', // deprecated
        TEXCOORD_1: 'uv2',
        COLOR_0: 'color',
        COLOR0: 'color', // deprecated
        COLOR: 'color', // deprecated
        WEIGHTS_0: 'skinWeight',
        WEIGHT: 'skinWeight', // deprecated
        JOINTS_0: 'skinIndex',
        JOINT: 'skinIndex' // deprecated
    }

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

    var INTERPOLATION = {
        CUBICSPLINE: THREE.InterpolateSmooth, // We use custom interpolation GLTFCubicSplineInterpolation for CUBICSPLINE.
        // KeyframeTrack.optimize() can't handle glTF Cubic Spline output values layout,
        // using THREE.InterpolateSmooth for KeyframeTrack instantiation to prevent optimization.
        // See KeyframeTrack.optimize() for the detail.
        LINEAR: THREE.InterpolateLinear,
        STEP: THREE.InterpolateDiscrete
    };

    var STATES_ENABLES = {
        2884: 'CULL_FACE',
        2929: 'DEPTH_TEST',
        3042: 'BLEND',
        3089: 'SCISSOR_TEST',
        32823: 'POLYGON_OFFSET_FILL',
        32926: 'SAMPLE_ALPHA_TO_COVERAGE'
    };

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

    /* UTILITY FUNCTIONS */

    function resolveURL(url, path) {

        // Invalid URL
        if (typeof url !== 'string' || url === '') return '';

        // Absolute URL http://,https://,//
        if (/^(https?:)?\/\//i.test(url)) return url;

        // Data URI
        if (/^data:.*,.*$/i.test(url)) return url;

        // Blob URL
        if (/^blob:.*$/i.test(url)) return url;

        // Relative URL
        return path + url;

    }

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

        return new THREE.MeshStandardMaterial({
            color: 0xFFFFFF,
            emissive: 0x000000,
            metalness: 1,
            roughness: 1,
            transparent: false,
            depthTest: true,
            side: THREE.FrontSide
        });

    }

    function addUnknownExtensionsToUserData(knownExtensions, object, objectDef) {

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

        for (var name in objectDef.extensions) {

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

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

            }

        }

    }

    /**
	 * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#morph-targets
	 *
	 * @param {THREE.Geometry} geometry
	 * @param {Array<GLTF.Target>} targets
	 * @param {Array<THREE.BufferAttribute>} accessors
	 */
    function addMorphTargets(geometry, targets, accessors) {

        var hasMorphPosition = false;
        var hasMorphNormal = false;

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

            var target = targets[i];

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

            if (hasMorphPosition && hasMorphNormal) break;

        }

        if (!hasMorphPosition && !hasMorphNormal) return;

        var morphPositions = [];
        var morphNormals = [];

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

            var target = targets[i];
            var attributeName = 'morphTarget' + i;

            if (hasMorphPosition) {

                // Three.js morph position is absolute value. The formula is
                //   basePosition
                //     + weight0 * ( morphPosition0 - basePosition )
                //     + weight1 * ( morphPosition1 - basePosition )
                //     ...
                // while the glTF one is relative
                //   basePosition
                //     + weight0 * glTFmorphPosition0
                //     + weight1 * glTFmorphPosition1
                //     ...
                // then we need to convert from relative to absolute here.

                if (target.POSITION !== undefined) {

                    // Cloning not to pollute original accessor
                    var positionAttribute = cloneBufferAttribute(accessors[target.POSITION]);
                    positionAttribute.name = attributeName;

                    var position = geometry.attributes.position;

                    for (var j = 0, jl = positionAttribute.count; j < jl; j++) {

                        positionAttribute.setXYZ(
							j,
							positionAttribute.getX(j) + position.getX(j),
							positionAttribute.getY(j) + position.getY(j),
							positionAttribute.getZ(j) + position.getZ(j)
						);

                    }

                } else {

                    positionAttribute = geometry.attributes.position;

                }

                morphPositions.push(positionAttribute);

            }

            if (hasMorphNormal) {

                // see target.POSITION's comment

                var normalAttribute;

                if (target.NORMAL !== undefined) {

                    var normalAttribute = cloneBufferAttribute(accessors[target.NORMAL]);
                    normalAttribute.name = attributeName;

                    var normal = geometry.attributes.normal;

                    for (var j = 0, jl = normalAttribute.count; j < jl; j++) {

                        normalAttribute.setXYZ(
							j,
							normalAttribute.getX(j) + normal.getX(j),
							normalAttribute.getY(j) + normal.getY(j),
							normalAttribute.getZ(j) + normal.getZ(j)
						);

                    }

                } else {

                    normalAttribute = geometry.attributes.normal;

                }

                morphNormals.push(normalAttribute);

            }

        }

        if (hasMorphPosition) geometry.morphAttributes.position = morphPositions;
        if (hasMorphNormal) geometry.morphAttributes.normal = morphNormals;

    }

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

        mesh.updateMorphTargets();

        if (meshDef.weights !== undefined) {

            for (var 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)) {

            var targetNames = meshDef.extras.targetNames;

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

                mesh.morphTargetDictionary = {};

                for (var 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 isPrimitiveEqual(a, b) {

        if (a.indices !== b.indices) {

            return false;

        }

        return isObjectEqual(a.attributes, b.attributes);

    }

    function isObjectEqual(a, b) {

        if (Object.keys(a).length !== Object.keys(b).length) return false;

        for (var key in a) {

            if (a[key] !== b[key]) return false;

        }

        return true;

    }

    function isArrayEqual(a, b) {

        if (a.length !== b.length) return false;

        for (var i = 0, il = a.length; i < il; i++) {

            if (a[i] !== b[i]) return false;

        }

        return true;

    }

    function getCachedGeometry(cache, newPrimitive) {

        for (var i = 0, il = cache.length; i < il; i++) {

            var cached = cache[i];

            if (isPrimitiveEqual(cached.primitive, newPrimitive)) return cached.promise;

        }

        return null;

    }

    function getCachedCombinedGeometry(cache, geometries) {

        for (var i = 0, il = cache.length; i < il; i++) {

            var cached = cache[i];

            if (isArrayEqual(geometries, cached.baseGeometries)) return cached.geometry;

        }

        return null;

    }

    function getCachedMultiPassGeometry(cache, geometry, primitives) {

        for (var i = 0, il = cache.length; i < il; i++) {

            var cached = cache[i];

            if (geometry === cached.baseGeometry && isArrayEqual(primitives, cached.primitives)) return cached.geometry;

        }

        return null;

    }

    function cloneBufferAttribute(attribute) {

        if (attribute.isInterleavedBufferAttribute) {

            var count = attribute.count;
            var itemSize = attribute.itemSize;
            var array = attribute.array.slice(0, count * itemSize);

            for (var i = 0; i < count; ++i) {

                array[i] = attribute.getX(i);
                if (itemSize >= 2) array[i + 1] = attribute.getY(i);
                if (itemSize >= 3) array[i + 2] = attribute.getZ(i);
                if (itemSize >= 4) array[i + 3] = attribute.getW(i);

            }

            return new THREE.BufferAttribute(array, itemSize, attribute.normalized);

        }

        return attribute.clone();

    }

    /**
	 * Checks if we can build a single Mesh with MultiMaterial from multiple primitives.
	 * Returns true if all primitives use the same attributes/morphAttributes/mode
	 * and also have index. Otherwise returns false.
	 *
	 * @param {Array<GLTF.Primitive>} primitives
	 * @return {Boolean}
	 */
    function isMultiPassGeometry(primitives) {

        if (primitives.length < 2) return false;

        var primitive0 = primitives[0];
        var targets0 = primitive0.targets || [];

        if (primitive0.indices === undefined) return false;

        for (var i = 1, il = primitives.length; i < il; i++) {

            var primitive = primitives[i];

            if (primitive0.mode !== primitive.mode) return false;
            if (primitive.indices === undefined) return false;
            if (!isObjectEqual(primitive0.attributes, primitive.attributes)) return false;

            var targets = primitive.targets || [];

            if (targets0.length !== targets.length) return false;

            for (var j = 0, jl = targets0.length; j < jl; j++) {

                if (!isObjectEqual(targets0[j], targets[j])) return false;

            }

        }

        return true;

    }

    /* GLTF PARSER */

    function GLTFParser(json, extensions, options) {

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

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

        // BufferGeometry caching
        this.primitiveCache = [];
        this.multiplePrimitivesCache = [];
        this.multiPassGeometryCache = []

        this.textureLoader = new THREE.TextureLoader(this.options.manager);
        this.textureLoader.setCrossOrigin(this.options.crossOrigin);

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

    }

    GLTFParser.prototype.parse = function (onLoad, onError) {

        var json = this.json;

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

        // Mark the special nodes/meshes in json for efficient parse
        this.markDefs();

        // Fire the callback on complete
        this.getMultiDependencies([

			'scene',
			'animation',
			'camera'

        ]).then(function (dependencies) {

            var scenes = dependencies.scenes || [];
            var scene = scenes[json.scene || 0];
            var animations = dependencies.animations || [];
            var cameras = dependencies.cameras || [];

            onLoad(scene, scenes, cameras, animations, json);

        }).catch(onError);

    };

    /**
	 * Marks the special nodes/meshes in json for efficient parse.
	 */
    GLTFParser.prototype.markDefs = function () {

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

        var meshReferences = {};
        var meshUses = {};

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

            var joints = skinDefs[skinIndex].joints;

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

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

            }

        }

        // Meshes can (and should) be reused by multiple nodes in a glTF asset. To
        // avoid having more than one THREE.Mesh with the same name, count
        // references and rename instances below.
        //
        // Example: CesiumMilkTruck sample model reuses "Wheel" meshes.
        for (var nodeIndex = 0, nodeLength = nodeDefs.length; nodeIndex < nodeLength; nodeIndex++) {

            var nodeDef = nodeDefs[nodeIndex];

            if (nodeDef.mesh !== undefined) {

                if (meshReferences[nodeDef.mesh] === undefined) {

                    meshReferences[nodeDef.mesh] = meshUses[nodeDef.mesh] = 0;

                }

                meshReferences[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;

                }

            }

        }

        this.json.meshReferences = meshReferences;
        this.json.meshUses = meshUses;

    };

    /**
	 * Requests the specified dependency asynchronously, with caching.
	 * @param {string} type
	 * @param {number} index
	 * @return {Promise<Object>}
	 */
    GLTFParser.prototype.getDependency = function (type, index) {

        var cacheKey = type + ':' + index;
        var 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.loadMesh(index);
                    break;

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

                case 'bufferView':
                    dependency = this.loadBufferView(index);
                    break;

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

                case 'material':
                    dependency = this.loadMaterial(index);
                    break;

                case 'texture':
                    dependency = this.loadTexture(index);
                    break;

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

                case 'animation':
                    dependency = this.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>>}
	 */
    GLTFParser.prototype.getDependencies = function (type) {

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

        if (!dependencies) {

            var parser = this;
            var 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;

    };

    /**
	 * Requests all multiple dependencies of the specified types asynchronously, with caching.
	 * @param {Array<string>} types
	 * @return {Promise<Object<Array<Object>>>}
	 */
    GLTFParser.prototype.getMultiDependencies = function (types) {

        var results = {};
        var pendings = [];

        for (var i = 0, il = types.length; i < il; i++) {

            var type = types[i];
            var value = this.getDependencies(type);

            value = value.then(function (key, value) {

                results[key] = value;

            }.bind(this, type + (type === 'mesh' ? 'es' : 's')));

            pendings.push(value);

        }

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

            return results;

        });

    };

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

        var bufferDef = this.json.buffers[bufferIndex];
        var 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);

        }

        var options = this.options;

        return new Promise(function (resolve, reject) {

            loader.load(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>}
	 */
    GLTFParser.prototype.loadBufferView = function (bufferViewIndex) {

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

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

            var byteLength = bufferViewDef.byteLength || 0;
            var 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<THREE.BufferAttribute|THREE.InterleavedBufferAttribute>}
	 */
    GLTFParser.prototype.loadAccessor = function (accessorIndex) {

        var parser = this;
        var json = this.json;

        var 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 null;

        }

        var 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) {

            var bufferView = bufferViews[0];

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

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

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

                var ibCacheKey = 'InterleavedBuffer:' + accessorDef.bufferView + ':' + accessorDef.componentType;
                var ib = parser.cache.get(ibCacheKey);

                if (!ib) {

                    // Use the full buffer if it's interleaved.
                    array = new TypedArray(bufferView);

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

                    parser.cache.add(ibCacheKey, ib);

                }

                bufferAttribute = new THREE.InterleavedBufferAttribute(ib, itemSize, byteOffset / elementBytes, normalized);

            } else {

                if (bufferView === null) {

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

                } else {

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

                }

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

            }

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

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

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

                var sparseIndices = new TypedArrayIndices(bufferViews[1], byteOffsetIndices, accessorDef.sparse.count * itemSizeIndices);
                var 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.setArray(bufferAttribute.array.slice());

                }

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

                    var 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>}
	 */
    GLTFParser.prototype.loadTexture = function (textureIndex) {

        var parser = this;
        var json = this.json;
        var options = this.options;
        var textureLoader = this.textureLoader;

        var URL = window.URL || window.webkitURL;

        var textureDef = json.textures[textureIndex];

        var textureExtensions = textureDef.extensions || {};

        var source;

        if (textureExtensions[EXTENSIONS.MSFT_TEXTURE_DDS]) {

            source = json.images[textureExtensions[EXTENSIONS.MSFT_TEXTURE_DDS].source];

        } else {

            source = json.images[textureDef.source];

        }

        var sourceURI = source.uri;
        var isObjectURL = false;

        if (source.bufferView !== undefined) {

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

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

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

            });

        }

        return Promise.resolve(sourceURI).then(function (sourceURI) {

            // Load Texture resource.

            var loader = THREE.Loader.Handlers.get(sourceURI);

            if (!loader) {

                loader = textureExtensions[EXTENSIONS.MSFT_TEXTURE_DDS]
					? parser.extensions[EXTENSIONS.MSFT_TEXTURE_DDS].ddsLoader
					: textureLoader;

            }

            return new Promise(function (resolve, reject) {

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

            });

        }).then(function (texture) {

            // Clean up resources and configure Texture.

            if (isObjectURL === true) {

                URL.revokeObjectURL(sourceURI);

            }

            texture.flipY = false;

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

            // .format of dds texture is set in DDSLoader
            if (!textureExtensions[EXTENSIONS.MSFT_TEXTURE_DDS]) {

                texture.format = textureDef.format !== undefined ? WEBGL_TEXTURE_FORMATS[textureDef.format] : THREE.RGBAFormat;

            }

            if (textureDef.internalFormat !== undefined && texture.format !== WEBGL_TEXTURE_FORMATS[textureDef.internalFormat]) {

                console.warn('THREE.GLTFLoader: Three.js does not support texture internalFormat which is different from texture format. ' +
											'internalFormat will be forced to be the same value as format.');

            }

            texture.type = textureDef.type !== undefined ? WEBGL_TEXTURE_DATATYPES[textureDef.type] : THREE.UnsignedByteType;

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

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

            return texture;

        });

    };

    /**
	 * Asynchronously assigns a texture to the given material parameters.
	 * @param {Object} materialParams
	 * @param {string} textureName
	 * @param {number} textureIndex
	 * @return {Promise}
	 */
    GLTFParser.prototype.assignTexture = function (materialParams, textureName, textureIndex) {

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

            materialParams[textureName] = texture;

        });

    };

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

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

        var materialType;
        var materialParams = {};
        var materialExtensions = materialDef.extensions || {};

        var pending = [];

        if (materialExtensions[EXTENSIONS.KHR_MATERIALS_PBR_SPECULAR_GLOSSINESS]) {

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

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

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

        } else {

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

            materialType = THREE.MeshStandardMaterial;

            var metallicRoughness = materialDef.pbrMetallicRoughness || {};

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

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

                var array = metallicRoughness.baseColorFactor;

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

            }

            if (metallicRoughness.baseColorTexture !== undefined) {

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

            }

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

            if (metallicRoughness.metallicRoughnessTexture !== undefined) {

                var textureIndex = metallicRoughness.metallicRoughnessTexture.index;
                pending.push(parser.assignTexture(materialParams, 'metalnessMap', textureIndex));
                pending.push(parser.assignTexture(materialParams, 'roughnessMap', textureIndex));

            }

        }

        if (materialDef.doubleSided === true) {

            materialParams.side = THREE.DoubleSide;

        }

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

        if (alphaMode === ALPHA_MODES.BLEND) {

            materialParams.transparent = true;

        } else {

            materialParams.transparent = false;

            if (alphaMode === ALPHA_MODES.MASK) {

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

            }

        }

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

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

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

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

                materialParams.normalScale.set(materialDef.normalTexture.scale, materialDef.normalTexture.scale);

            }

        }

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

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

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

                materialParams.aoMapIntensity = materialDef.occlusionTexture.strength;

            }

        }

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

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

        }

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

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

        }

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

            var material;

            if (materialType === THREE.ShaderMaterial) {

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

            } else {

                material = new materialType(materialParams);

            }

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

            // Normal map textures use OpenGL conventions:
            // https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#materialnormaltexture
            if (material.normalScale) {

                material.normalScale.y = -material.normalScale.y;

            }

            // baseColorTexture, emissiveTexture, and specularGlossinessTexture use sRGB encoding.
            if (material.map) material.map.encoding = THREE.sRGBEncoding;
            if (material.emissiveMap) material.emissiveMap.encoding = THREE.sRGBEncoding;
            if (material.specularMap) material.specularMap.encoding = THREE.sRGBEncoding;

            if (materialDef.extras) material.userData = materialDef.extras;

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

            return material;

        });

    };

    /**
	 * @param  {THREE.BufferGeometry} geometry
	 * @param  {GLTF.Primitive} primitiveDef
	 * @param  {Array<THREE.BufferAttribute>} accessors
	 */
    function addPrimitiveAttributes(geometry, primitiveDef, accessors) {

        var attributes = primitiveDef.attributes;

        for (var gltfAttributeName in attributes) {

            var threeAttributeName = ATTRIBUTES[gltfAttributeName];
            var bufferAttribute = accessors[attributes[gltfAttributeName]];

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

            geometry.addAttribute(threeAttributeName, bufferAttribute);

        }

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

            geometry.setIndex(accessors[primitiveDef.indices]);

        }

        if (primitiveDef.targets !== undefined) {

            addMorphTargets(geometry, primitiveDef.targets, accessors);

        }

        if (primitiveDef.extras !== undefined) {

            geometry.userData = primitiveDef.extras;

        }

    }

    /**
	 * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#geometry
	 *
	 * Creates BufferGeometries from primitives.
	 * If we can build a single BufferGeometry with .groups from multiple primitives, returns one BufferGeometry.
	 * Otherwise, returns BufferGeometries without .groups as many as primitives.
	 *
	 * @param {Array<Object>} primitives
	 * @return {Promise<Array<THREE.BufferGeometry>>}
	 */
    GLTFParser.prototype.loadGeometries = function (primitives) {

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

        var isMultiPass = isMultiPassGeometry(primitives);
        var originalPrimitives;

        if (isMultiPass) {

            originalPrimitives = primitives; // save original primitives and use later

            // We build a single BufferGeometry with .groups from multiple primitives
            // because all primitives share the same attributes/morph/mode and have indices.

            primitives = [primitives[0]];

            // Sets .groups and combined indices to a geometry later in this method.

        }

        return this.getDependencies('accessor').then(function (accessors) {

            var pending = [];

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

                var primitive = primitives[i];

                // See if we've already created this geometry
                var cached = getCachedGeometry(cache, primitive);

                if (cached) {

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

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

                    // Use DRACO geometry if available
                    var geometryPromise = extensions[EXTENSIONS.KHR_DRACO_MESH_COMPRESSION]
						.decodePrimitive(primitive, parser)
						.then(function (geometry) {

						    addPrimitiveAttributes(geometry, primitive, accessors);

						    return geometry;

						});

                    cache.push({ primitive: primitive, promise: geometryPromise });

                    pending.push(geometryPromise);

                } else {

                    // Otherwise create a new geometry
                    var geometry = new THREE.BufferGeometry();

                    addPrimitiveAttributes(geometry, primitive, accessors);

                    var geometryPromise = Promise.resolve(geometry);

                    // Cache this geometry
                    cache.push({ primitive: primitive, promise: geometryPromise });

                    pending.push(geometryPromise);

                }

            }

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

                if (isMultiPass) {

                    var baseGeometry = geometries[0];

                    // See if we've already created this combined geometry
                    var cache = parser.multiPassGeometryCache;
                    var cached = getCachedMultiPassGeometry(cache, baseGeometry, originalPrimitives);

                    if (cached !== null) return [cached.geometry];

                    // Cloning geometry because of index override.
                    // Attributes can be reused so cloning by myself here.
                    var geometry = new THREE.BufferGeometry();

                    geometry.name = baseGeometry.name;
                    geometry.userData = baseGeometry.userData;

                    for (var key in baseGeometry.attributes) geometry.addAttribute(key, baseGeometry.attributes[key]);
                    for (var key in baseGeometry.morphAttributes) geometry.morphAttributes[key] = baseGeometry.morphAttributes[key];

                    var indices = [];
                    var offset = 0;

                    for (var i = 0, il = originalPrimitives.length; i < il; i++) {

                        var accessor = accessors[originalPrimitives[i].indices];

                        for (var j = 0, jl = accessor.count; j < jl; j++) indices.push(accessor.array[j]);

                        geometry.addGroup(offset, accessor.count, i);

                        offset += accessor.count;

                    }

                    geometry.setIndex(indices);

                    cache.push({ geometry: geometry, baseGeometry: baseGeometry, primitives: originalPrimitives });

                    return [geometry];

                } else if (geometries.length > 1 && THREE.BufferGeometryUtils !== undefined) {

                    // Tries to merge geometries with BufferGeometryUtils if possible

                    for (var i = 1, il = primitives.length; i < il; i++) {

                        // can't merge if draw mode is different
                        if (primitives[0].mode !== primitives[i].mode) return geometries;

                    }

                    // See if we've already created this combined geometry
                    var cache = parser.multiplePrimitivesCache;
                    var cached = getCachedCombinedGeometry(cache, geometries);

                    if (cached) {

                        if (cached.geometry !== null) return [cached.geometry];

                    } else {

                        var geometry = THREE.BufferGeometryUtils.mergeBufferGeometries(geometries, true);

                        cache.push({ geometry: geometry, baseGeometries: geometries });

                        if (geometry !== null) return [geometry];

                    }

                }

                return geometries;

            });

        });

    };

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

        var scope = this;
        var json = this.json;
        var extensions = this.extensions;

        var meshDef = this.json.meshes[meshIndex];

        return this.getMultiDependencies([

			'accessor',
			'material'

        ]).then(function (dependencies) {

            var primitives = meshDef.primitives;
            var originalMaterials = [];

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

                originalMaterials[i] = primitives[i].material === undefined
					? createDefaultMaterial()
					: dependencies.materials[primitives[i].material];

            }

            return scope.loadGeometries(primitives).then(function (geometries) {

                var isMultiMaterial = geometries.length === 1 && geometries[0].groups.length > 0;

                var meshes = [];

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

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

                    // 1. create Mesh

                    var mesh;

                    var material = isMultiMaterial ? originalMaterials : originalMaterials[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 THREE.SkinnedMesh(geometry, material)
							: new THREE.Mesh(geometry, material);

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

                            mesh.drawMode = THREE.TriangleStripDrawMode;

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

                            mesh.drawMode = THREE.TriangleFanDrawMode;

                        }

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

                        mesh = new THREE.LineSegments(geometry, material);

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

                        mesh = new THREE.Line(geometry, material);

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

                        mesh = new THREE.LineLoop(geometry, material);

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

                        mesh = new THREE.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 = meshDef.name || ('mesh_' + meshIndex);

                    if (geometries.length > 1) mesh.name += '_' + i;

                    if (meshDef.extras !== undefined) mesh.userData = meshDef.extras;

                    meshes.push(mesh);

                    // 2. update Material depending on Mesh and BufferGeometry

                    var materials = isMultiMaterial ? mesh.material : [mesh.material];

                    var useVertexColors = geometry.attributes.color !== undefined;
                    var useFlatShading = geometry.attributes.normal === undefined;
                    var useSkinning = mesh.isSkinnedMesh === true;
                    var useMorphTargets = Object.keys(geometry.morphAttributes).length > 0;
                    var useMorphNormals = useMorphTargets && geometry.morphAttributes.normal !== undefined;

                    for (var j = 0, jl = materials.length; j < jl; j++) {

                        var material = materials[j];

                        if (mesh.isPoints) {

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

                            var pointsMaterial = scope.cache.get(cacheKey);

                            if (!pointsMaterial) {

                                pointsMaterial = new THREE.PointsMaterial();
                                THREE.Material.prototype.copy.call(pointsMaterial, material);
                                pointsMaterial.color.copy(material.color);
                                pointsMaterial.map = material.map;
                                pointsMaterial.lights = false;  // PointsMaterial doesn't support lights yet

                                scope.cache.add(cacheKey, pointsMaterial);

                            }

                            material = pointsMaterial;

                        } else if (mesh.isLine) {

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

                            var lineMaterial = scope.cache.get(cacheKey);

                            if (!lineMaterial) {

                                lineMaterial = new THREE.LineBasicMaterial();
                                THREE.Material.prototype.copy.call(lineMaterial, material);
                                lineMaterial.color.copy(material.color);
                                lineMaterial.lights = false;  // LineBasicMaterial doesn't support lights yet

                                scope.cache.add(cacheKey, lineMaterial);

                            }

                            material = lineMaterial;

                        }

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

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

                            if (material.isGLTFSpecularGlossinessMaterial) cacheKey += 'specular-glossiness:';
                            if (useSkinning) cacheKey += 'skinning:';
                            if (useVertexColors) cacheKey += 'vertex-colors:';
                            if (useFlatShading) cacheKey += 'flat-shading:';
                            if (useMorphTargets) cacheKey += 'morph-targets:';
                            if (useMorphNormals) cacheKey += 'morph-normals:';

                            var cachedMaterial = scope.cache.get(cacheKey);

                            if (!cachedMaterial) {

                                cachedMaterial = material.isGLTFSpecularGlossinessMaterial
										? extensions[EXTENSIONS.KHR_MATERIALS_PBR_SPECULAR_GLOSSINESS].cloneMaterial(material)
										: material.clone();

                                if (useSkinning) cachedMaterial.skinning = true;
                                if (useVertexColors) cachedMaterial.vertexColors = THREE.VertexColors;
                                if (useFlatShading) cachedMaterial.flatShading = true;
                                if (useMorphTargets) cachedMaterial.morphTargets = true;
                                if (useMorphNormals) cachedMaterial.morphNormals = true;

                                scope.cache.add(cacheKey, cachedMaterial);

                            }

                            material = cachedMaterial;

                        }

                        materials[j] = material;

                        // workarounds for mesh and geometry

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

                            console.log('THREE.GLTFLoader: Duplicating UVs to support aoMap.');
                            geometry.addAttribute('uv2', new THREE.BufferAttribute(geometry.attributes.uv.array, 2));

                        }

                        if (material.isGLTFSpecularGlossinessMaterial) {

                            // for GLTFSpecularGlossinessMaterial(ShaderMaterial) uniforms runtime update
                            mesh.onBeforeRender = extensions[EXTENSIONS.KHR_MATERIALS_PBR_SPECULAR_GLOSSINESS].refreshUniforms;

                        }

                    }

                    mesh.material = isMultiMaterial ? materials : materials[0];

                }

                if (meshes.length === 1) {

                    return meshes[0];

                }

                var group = new THREE.Group();

                for (var 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>}
	 */
    GLTFParser.prototype.loadCamera = function (cameraIndex) {

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

        if (!params) {

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

        }

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

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

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

            camera = new THREE.OrthographicCamera(params.xmag / -2, params.xmag / 2, params.ymag / 2, params.ymag / -2, params.znear, params.zfar);

        }

        if (cameraDef.name !== undefined) camera.name = cameraDef.name;
        if (cameraDef.extras) camera.userData = cameraDef.extras;

        return Promise.resolve(camera);

    };

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

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

        var 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<THREE.AnimationClip>}
	 */
    GLTFParser.prototype.loadAnimation = function (animationIndex) {

        var json = this.json;

        var animationDef = this.json.animations[animationIndex];

        return this.getMultiDependencies([

			'accessor',
			'node'

        ]).then(function (dependencies) {

            var tracks = [];

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

                var channel = animationDef.channels[i];
                var sampler = animationDef.samplers[channel.sampler];

                if (sampler) {

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

                    var inputAccessor = dependencies.accessors[input];
                    var outputAccessor = dependencies.accessors[output];

                    var node = dependencies.nodes[name];

                    if (node) {

                        node.updateMatrix();
                        node.matrixAutoUpdate = true;

                        var TypedKeyframeTrack;

                        switch (PATH_PROPERTIES[target.path]) {

                            case PATH_PROPERTIES.weights:

                                TypedKeyframeTrack = THREE.NumberKeyframeTrack;
                                break;

                            case PATH_PROPERTIES.rotation:

                                TypedKeyframeTrack = THREE.QuaternionKeyframeTrack;
                                break;

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

                                TypedKeyframeTrack = THREE.VectorKeyframeTrack;
                                break;

                        }

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

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

                        var targetNames = [];

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

                            // node can be THREE.Group here but
                            // PATH_PROPERTIES.weights(morphTargetInfluences) should be
                            // the property of a mesh object under group.

                            node.traverse(function (object) {

                                if (object.isMesh === true && object.morphTargetInfluences) {

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

                                }

                            });

                        } else {

                            targetNames.push(targetName);

                        }

                        // KeyframeTrack.optimize() will modify given 'times' and 'values'
                        // buffers before creating a truncated copy to keep. Because buffers may
                        // be reused by other tracks, make copies here.
                        for (var j = 0, jl = targetNames.length; j < jl; j++) {

                            var track = new TypedKeyframeTrack(
								targetNames[j] + '.' + PATH_PROPERTIES[target.path],
								THREE.AnimationUtils.arraySlice(inputAccessor.array, 0),
								THREE.AnimationUtils.arraySlice(outputAccessor.array, 0),
								interpolation
							);

                            // Here is the trick to enable custom interpolation.
                            // Overrides .createInterpolant in a factory method which creates custom interpolation.
                            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.

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

                                };

                                // Workaround, provide an alternate way to know if the interpolant type is cubis spline to track.
                                // track.getInterpolation() doesn't return valid value for custom interpolant.
                                track.createInterpolant.isInterpolantFactoryMethodGLTFCubicSpline = true;

                            }

                            tracks.push(track);

                        }

                    }

                }

            }

            var name = animationDef.name !== undefined ? animationDef.name : 'animation_' + animationIndex;

            return new THREE.AnimationClip(name, undefined, tracks);

        });

    };

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

        var json = this.json;
        var extensions = this.extensions;

        var meshReferences = this.json.meshReferences;
        var meshUses = this.json.meshUses;

        var nodeDef = this.json.nodes[nodeIndex];

        return this.getMultiDependencies([

			'mesh',
			'skin',
			'camera',
			'light'

        ]).then(function (dependencies) {

            var node;

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

                node = new THREE.Bone();

            } else if (nodeDef.mesh !== undefined) {

                var mesh = dependencies.meshes[nodeDef.mesh];

                node = mesh.clone();

                // for Specular-Glossiness
                if (mesh.isGroup === true) {

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

                        var child = mesh.children[i];

                        if (child.material && child.material.isGLTFSpecularGlossinessMaterial === true) {

                            node.children[i].onBeforeRender = child.onBeforeRender;

                        }

                    }

                } else {

                    if (mesh.material && mesh.material.isGLTFSpecularGlossinessMaterial === true) {

                        node.onBeforeRender = mesh.onBeforeRender;

                    }

                }

                if (meshReferences[nodeDef.mesh] > 1) {

                    node.name += '_instance_' + meshUses[nodeDef.mesh]++;

                }

            } else if (nodeDef.camera !== undefined) {

                node = dependencies.cameras[nodeDef.camera];

            } else if (nodeDef.extensions
					 && nodeDef.extensions[EXTENSIONS.KHR_LIGHTS]
					 && nodeDef.extensions[EXTENSIONS.KHR_LIGHTS].light !== undefined) {

                var lights = extensions[EXTENSIONS.KHR_LIGHTS].lights;
                node = lights[nodeDef.extensions[EXTENSIONS.KHR_LIGHTS].light];

            } else {

                node = new THREE.Object3D();

            }

            if (nodeDef.name !== undefined) {

                node.name = THREE.PropertyBinding.sanitizeNodeName(nodeDef.name);

            }

            if (nodeDef.extras) node.userData = nodeDef.extras;

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

            if (nodeDef.matrix !== undefined) {

                var matrix = new THREE.Matrix4();
                matrix.fromArray(nodeDef.matrix);
                node.applyMatrix(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);

                }

            }

            return node;

        });

    };

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

        // scene node hierachy builder

        function buildNodeHierachy(nodeId, parentObject, json, allNodes, skins) {

            var node = allNodes[nodeId];
            var nodeDef = json.nodes[nodeId];

            // build skeleton here as well

            if (nodeDef.skin !== undefined) {

                var meshes = node.isGroup === true ? node.children : [node];

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

                    var mesh = meshes[i];
                    var skinEntry = skins[nodeDef.skin];

                    var bones = [];
                    var boneInverses = [];

                    for (var j = 0, jl = skinEntry.joints.length; j < jl; j++) {

                        var jointId = skinEntry.joints[j];
                        var jointNode = allNodes[jointId];

                        if (jointNode) {

                            bones.push(jointNode);

                            var mat = new THREE.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.', jointId);

                        }

                    }

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

                }

            }

            // build node hierachy

            parentObject.add(node);

            if (nodeDef.children) {

                var children = nodeDef.children;

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

                    var child = children[i];
                    buildNodeHierachy(child, node, json, allNodes, skins);

                }

            }

        }

        return function loadScene(sceneIndex) {

            var json = this.json;
            var extensions = this.extensions;
            var sceneDef = this.json.scenes[sceneIndex];

            return this.getMultiDependencies([

				'node',
				'skin'

            ]).then(function (dependencies) {

                var scene = new THREE.Scene();
                if (sceneDef.name !== undefined) scene.name = sceneDef.name;

                if (sceneDef.extras) scene.userData = sceneDef.extras;

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

                var nodeIds = sceneDef.nodes || [];

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

                    buildNodeHierachy(nodeIds[i], scene, json, dependencies.nodes, dependencies.skins);

                }

                // Ambient lighting, if present, is always attached to the scene root.
                if (sceneDef.extensions
						 && sceneDef.extensions[EXTENSIONS.KHR_LIGHTS]
						 && sceneDef.extensions[EXTENSIONS.KHR_LIGHTS].light !== undefined) {

                    var lights = extensions[EXTENSIONS.KHR_LIGHTS].lights;
                    scene.add(lights[sceneDef.extensions[EXTENSIONS.KHR_LIGHTS].light]);

                }

                return scene;

            });

        };

    }();

    return GLTFLoader;

})();
