text: /**
   * @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
   */
  
  var THREE = require("three");
  var DRACOLoader = require("./THREEDracoLoader");
  var _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 resourcePath;
  
        if (this.resourcePath !== undefined) {
          resourcePath = this.resourcePath;
        } else if (this.path !== undefined) {
          resourcePath = this.path;
        } else {
          resourcePath = THREE.LoaderUtils.extractUrlBase(url);
        }
  
        // Tells the LoadingManager to track an extra item, which resolves after
        // the model is fully loaded. This means the count of items loaded will
        // be incorrect, but ensures manager.onLoad() does not fire early.
        scope.manager.itemStart(url);
  
        var _onError = function(e) {
          if (onError) {
            onError(e);
          } else {
            console.error(e);
          }
  
          scope.manager.itemError(url);
          scope.manager.itemEnd(url);
        };
  
        var loader = new THREE.FileLoader(scope.manager);
  
        loader.setPath(this.path);
        loader.setResponseType("arraybuffer");
  
        loader.load(
          url,
          function(data) {
            try {
              scope.parse(
                data,
                resourcePath,
                function(gltf) {
                  onLoad(gltf);
  
                  scope.manager.itemEnd(url);
                },
                _onError
              );
            } catch (e) {
              _onError(e);
            }
          },
          onProgress,
          _onError
        );
      },
  
      setCrossOrigin: function(value) {
        this.crossOrigin = value;
        return this;
      },
  
      setPath: function(value) {
        this.path = value;
        return this;
      },
  
      setResourcePath: function(value) {
        this.resourcePath = 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_PUNCTUAL:
                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(json);
                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(json);
                break;
  
              case EXTENSIONS.KHR_TEXTURE_TRANSFORM:
                extensions[
                  EXTENSIONS.KHR_TEXTURE_TRANSFORM
                ] = new GLTFTextureTransformExtension(json);
                break;
  
              default:
                if (extensionsRequired.indexOf(extensionName) >= 0) {
                  console.warn(
                    'THREE.GLTFLoader: Unknown extension "' + extensionName + '".'
                  );
                }
            }
          }
        }
  
        var parser = new GLTFParser(json, extensions, {
          path: path || this.resourcePath || "",
          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_PUNCTUAL: "KHR_lights_punctual",
      KHR_MATERIALS_PBR_SPECULAR_GLOSSINESS:
        "KHR_materials_pbrSpecularGlossiness",
      KHR_MATERIALS_UNLIT: "KHR_materials_unlit",
      KHR_TEXTURE_TRANSFORM: "KHR_texture_transform",
      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_PUNCTUAL;
  
      var extension =
        (json.extensions && json.extensions[EXTENSIONS.KHR_LIGHTS_PUNCTUAL]) ||
        {};
      this.lightDefs = extension.lights || [];
    }
  
    GLTFLightsExtension.prototype.loadLight = function(lightIndex) {
      var lightDef = this.lightDefs[lightIndex];
      var lightNode;
  
      var color = new THREE.Color(0xffffff);
      if (lightDef.color !== undefined) color.fromArray(lightDef.color);
  
      var range = lightDef.range !== undefined ? lightDef.range : 0;
  
      switch (lightDef.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);
          lightNode.distance = range;
          break;
  
        case "spot":
          lightNode = new THREE.SpotLight(color);
          lightNode.distance = range;
          // Handle spotlight properties.
          lightDef.spot = lightDef.spot || {};
          lightDef.spot.innerConeAngle =
            lightDef.spot.innerConeAngle !== undefined
              ? lightDef.spot.innerConeAngle
              : 0;
          lightDef.spot.outerConeAngle =
            lightDef.spot.outerConeAngle !== undefined
              ? lightDef.spot.outerConeAngle
              : Math.PI / 4.0;
          lightNode.angle = lightDef.spot.outerConeAngle;
          lightNode.penumbra =
            1.0 - lightDef.spot.innerConeAngle / lightDef.spot.outerConeAngle;
          lightNode.target.position.set(0, 0, -1);
          lightNode.add(lightNode.target);
          break;
  
        default:
          throw new Error(
            'THREE.GLTFLoader: Unexpected light type, "' + lightDef.type + '".'
          );
      }
  
      lightNode.decay = 2;
  
      if (lightDef.intensity !== undefined)
        lightNode.intensity = lightDef.intensity;
  
      lightNode.name = lightDef.name || "light_" + lightIndex;
  
      return Promise.resolve(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
            )
          );
        }
      }
  
      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;
      DRACOLoader.getDecoderModule();
    }
  
    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
            );
          });
        });
    };
  
    /**
     * Texture Transform Extension
     *
     * Specification:
     */
    function GLTFTextureTransformExtension(json) {
      this.name = EXTENSIONS.KHR_TEXTURE_TRANSFORM;
    }
  
    GLTFTextureTransformExtension.prototype.extendTexture = function(
      texture,
      transform
    ) {
      texture = texture.clone();
  
      if (transform.offset !== undefined) {
        texture.offset.fromArray(transform.offset);
      }
  
      if (transform.rotation !== undefined) {
        texture.rotation = transform.rotation;
      }
  
      if (transform.scale !== undefined) {
        texture.repeat.fromArray(transform.scale);
      }
  
      if (transform.texCoord !== undefined) {
        console.warn(
          'THREE.GLTFLoader: Custom UV sets in "' +
            this.name +
            '" extension not yet supported.'
        );
      }
  
      texture.needsUpdate = true;
  
      return texture;
    };
  
    /**
     * 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
              )
            );
          }
  
          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 specGlossMapDef = pbrSpecularGlossiness.specularGlossinessTexture;
            pending.push(
              parser.assignTexture(params, "glossinessMap", specGlossMapDef)
            );
            pending.push(
              parser.assignTexture(params, "specularMap", specGlossMapDef)
            );
          }
  
          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;
            }
  
            if (uvScaleMap.matrixAutoUpdate === true) {
              uvScaleMap.updateMatrix();
            }
  
            uniforms.uvTransform.value.copy(uvScaleMap.matrix);
          }
  
          if (material.envMap) {
            uniforms.envMap.value = material.envMap;
            uniforms.envMapIntensity.value = material.envMapIntensity;
  
            // don't flip CubeTexture envMaps, flip everything else:
            //  WebGLRenderTargetCube will be flipped for backwards compatibility
            //  WebGLRenderTargetCube.texture will be flipped because it's a Texture and NOT a CubeTexture
            // this check must be handled differently, or removed entirely, if WebGLRenderTargetCube uses a CubeTexture in the future
            uniforms.flipEnvMap.value = material.envMap.isCubeTexture ? -1 : 1;
  
            uniforms.reflectivity.value = material.reflectivity;
            uniforms.refractionRatio.value = material.refractionRatio;
  
            uniforms.maxMipLevel.value = renderer.properties.get(
              material.envMap
            ).__maxMipLevel;
          }
  
          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.copySampleValue_ = function(index) {
      // Copies a sample value to the result buffer. See description of glTF
      // CUBICSPLINE values layout in interpolate_() function below.
  
      var result = this.resultBuffer,
        values = this.sampleValues,
        valueSize = this.valueSize,
        offset = index * valueSize * 3 + valueSize;
  
      for (var i = 0; i !== valueSize; i++) {
        result[i] = values[offset + i];
      }
  
      return result;
    };
  
    GLTFCubicSplineInterpolant.prototype.beforeStart_ =
      GLTFCubicSplineInterpolant.prototype.copySampleValue_;
  
    GLTFCubicSplineInterpolant.prototype.afterEnd_ =
      GLTFCubicSplineInterpolant.prototype.copySampleValue_;
  
    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 s2 = -2 * ppp + 3 * pp;
      var s3 = ppp - pp;
      var s0 = 1 - s2;
      var s1 = s3 - pp + p;
  
      // 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_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",
      TEXCOORD_1: "uv2",
      COLOR_0: "color",
      WEIGHTS_0: "skinWeight",
      JOINTS_0: "skinIndex"
    };
  
    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"
    };
  
    var MIME_TYPE_FORMATS = {
      "image/png": THREE.RGBAFormat,
      "image/jpeg": THREE.RGBFormat
    };
  
    /* 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];
        }
      }
    }
  
    /**
     * @param {THREE.Object3D|THREE.Material|THREE.BufferGeometry} object
     * @param {GLTF.definition} gltfDef
     */
    function assignExtrasToUserData(object, gltfDef) {
      if (gltfDef.extras !== undefined) {
        if (typeof gltfDef.extras === "object") {
          object.userData = gltfDef.extras;
        } else {
          console.warn(
            "THREE.GLTFLoader: Ignoring primitive type .extras, " + gltfDef.extras
          );
        }
      }
    }
  
    /**
     * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#morph-targets
     *
     * @param {THREE.BufferGeometry} geometry
     * @param {Array<GLTF.Target>} targets
     * @param {GLTFParser} parser
     * @return {Promise<THREE.BufferGeometry>}
     */
    function addMorphTargets(geometry, targets, parser) {
      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 Promise.resolve(geometry);
  
      var pendingPositionAccessors = [];
      var pendingNormalAccessors = [];
  
      for (var i = 0, il = targets.length; i < il; i++) {
        var target = targets[i];
  
        if (hasMorphPosition) {
          // TODO: Error-prone use of a callback inside a loop.
          var accessor =
            target.POSITION !== undefined
              ? parser
                  .getDependency("accessor", target.POSITION)
                  .then(function(accessor) {
                    // Cloning not to pollute original accessor below
                    return cloneBufferAttribute(accessor);
                  })
              : geometry.attributes.position;
  
          pendingPositionAccessors.push(accessor);
        }
  
        if (hasMorphNormal) {
          // TODO: Error-prone use of a callback inside a loop.
          var accessor =
            target.NORMAL !== undefined
              ? parser
                  .getDependency("accessor", target.NORMAL)
                  .then(function(accessor) {
                    return cloneBufferAttribute(accessor);
                  })
              : geometry.attributes.normal;
  
          pendingNormalAccessors.push(accessor);
        }
      }
  
      return Promise.all([
        Promise.all(pendingPositionAccessors),
        Promise.all(pendingNormalAccessors)
      ]).then(function(accessors) {
        var morphPositions = accessors[0];
        var morphNormals = accessors[1];
  
        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) {
              var positionAttribute = morphPositions[i];
              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)
                );
              }
            }
          }
  
          if (hasMorphNormal) {
            // see target.POSITION's comment
  
            if (target.NORMAL !== undefined) {
              var normalAttribute = morphNormals[i];
              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)
                );
              }
            }
          }
        }
  
        if (hasMorphPosition) geometry.morphAttributes.position = morphPositions;
        if (hasMorphNormal) geometry.morphAttributes.normal = morphNormals;
  
        return geometry;
      });
    }
  
    /**
     * @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) {
      var dracoExtA = a.extensions
        ? a.extensions[EXTENSIONS.KHR_DRACO_MESH_COMPRESSION]
        : undefined;
      var dracoExtB = b.extensions
        ? b.extensions[EXTENSIONS.KHR_DRACO_MESH_COMPRESSION]
        : undefined;
  
      if (dracoExtA && dracoExtB) {
        if (dracoExtA.bufferView !== dracoExtB.bufferView) return false;
  
        return isObjectEqual(dracoExtA.attributes, dracoExtB.attributes);
      }
  
      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, j = 0; i < count; ++i) {
          array[j++] = attribute.getX(i);
          if (itemSize >= 2) array[j++] = attribute.getY(i);
          if (itemSize >= 3) array[j++] = attribute.getZ(i);
          if (itemSize >= 4) array[j++] = 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 (
          primitive.extensions &&
          primitive.extensions[EXTENSIONS.KHR_DRACO_MESH_COMPRESSION]
        )
          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<THREE.Object3D|THREE.Material|THREE.Texture|THREE.AnimationClip|ArrayBuffer|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;
  
          case "light":
            dependency = this.extensions[
              EXTENSIONS.KHR_LIGHTS_PUNCTUAL
            ].loadLight(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 pending = [];
  
      for (var i = 0, il = types.length; i < il; i++) {
        var type = types[i];
        var value = this.getDependencies(type);
  
        // TODO: Error-prone use of a callback inside a loop.
        value = value.then(
          function(key, value) {
            results[key] = value;
          }.bind(this, type + (type === "mesh" ? "es" : "s"))
        );
  
        pending.push(value);
      }
  
      return Promise.all(pending).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 Promise.resolve(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 =
          accessorDef.bufferView !== undefined
            ? json.bufferViews[accessorDef.bufferView].byteStride
            : undefined;
        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;
  
          // Ignore unknown mime types, like DDS files.
          if (source.mimeType in MIME_TYPE_FORMATS) {
            texture.format = MIME_TYPE_FORMATS[source.mimeType];
          }
  
          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} mapName
     * @param {Object} mapDef
     * @return {Promise}
     */
    GLTFParser.prototype.assignTexture = function(
      materialParams,
      mapName,
      mapDef
    ) {
      var parser = this;
  
      return this.getDependency("texture", mapDef.index).then(function(texture) {
        if (parser.extensions[EXTENSIONS.KHR_TEXTURE_TRANSFORM]) {
          var transform =
            mapDef.extensions !== undefined
              ? mapDef.extensions[EXTENSIONS.KHR_TEXTURE_TRANSFORM]
              : undefined;
  
          if (transform) {
            texture = parser.extensions[
              EXTENSIONS.KHR_TEXTURE_TRANSFORM
            ].extendTexture(texture, transform);
          }
        }
  
        materialParams[mapName] = 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 = 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
            )
          );
        }
  
        materialParams.metalness =
          metallicRoughness.metallicFactor !== undefined
            ? metallicRoughness.metallicFactor
            : 1.0;
        materialParams.roughness =
          metallicRoughness.roughnessFactor !== undefined
            ? metallicRoughness.roughnessFactor
            : 1.0;
  
        if (metallicRoughness.metallicRoughnessTexture !== undefined) {
          pending.push(
            parser.assignTexture(
              materialParams,
              "metalnessMap",
              metallicRoughness.metallicRoughnessTexture
            )
          );
          pending.push(
            parser.assignTexture(
              materialParams,
              "roughnessMap",
              metallicRoughness.metallicRoughnessTexture
            )
          );
        }
      }
  
      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
          )
        );
  
        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
          )
        );
  
        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
          )
        );
      }
  
      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;
  
        assignExtrasToUserData(material, materialDef);
  
        if (materialDef.extensions)
          addUnknownExtensionsToUserData(extensions, material, materialDef);
  
        return material;
      });
    };
  
    /**
     * @param {THREE.BufferGeometry} geometry
     * @param {GLTF.Primitive} primitiveDef
     * @param {GLTFParser} parser
     * @return {Promise<THREE.BufferGeometry>}
     */
    function addPrimitiveAttributes(geometry, primitiveDef, parser) {
      var attributes = primitiveDef.attributes;
  
      var pending = [];
  
      function assignAttributeAccessor(accessorIndex, attributeName) {
        return parser
          .getDependency("accessor", accessorIndex)
          .then(function(accessor) {
            geometry.addAttribute(attributeName, accessor);
          });
      }
  
      for (var gltfAttributeName in attributes) {
        var threeAttributeName = ATTRIBUTES[gltfAttributeName];
  
        if (!threeAttributeName) continue;
  
        // Skip attributes already provided by e.g. Draco extension.
        if (threeAttributeName in geometry.attributes) continue;
  
        pending.push(
          assignAttributeAccessor(
            attributes[gltfAttributeName],
            threeAttributeName
          )
        );
      }
  
      if (primitiveDef.indices !== undefined && !geometry.index) {
        var accessor = parser
          .getDependency("accessor", primitiveDef.indices)
          .then(function(accessor) {
            geometry.setIndex(accessor);
          });
  
        pending.push(accessor);
      }
  
      assignExtrasToUserData(geometry, primitiveDef);
  
      return Promise.all(pending).then(function() {
        return primitiveDef.targets !== undefined
          ? addMorphTargets(geometry, primitiveDef.targets, parser)
          : geometry;
      });
    }
  
    /**
     * 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<GLTF.Primitive>} 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.
      }
  
      function createDracoPrimitive(primitive) {
        return extensions[EXTENSIONS.KHR_DRACO_MESH_COMPRESSION]
          .decodePrimitive(primitive, parser)
          .then(function(geometry) {
            return addPrimitiveAttributes(geometry, primitive, parser);
          });
      }
  
      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 {
          var geometryPromise;
  
          if (
            primitive.extensions &&
            primitive.extensions[EXTENSIONS.KHR_DRACO_MESH_COMPRESSION]
          ) {
            // Use DRACO geometry if available
            geometryPromise = createDracoPrimitive(primitive);
          } else {
            // Otherwise create a new geometry
            geometryPromise = addPrimitiveAttributes(
              new THREE.BufferGeometry(),
              primitive,
              parser
            );
          }
  
          // 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 pendingIndices = [];
  
          for (var i = 0, il = originalPrimitives.length; i < il; i++) {
            pendingIndices.push(
              parser.getDependency("accessor", originalPrimitives[i].indices)
            );
          }
  
          return Promise.all(pendingIndices).then(function(accessors) {
            var indices = [];
            var offset = 0;
  
            for (var i = 0, il = originalPrimitives.length; i < il; i++) {
              var accessor = accessors[i];
  
              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 parser = this;
      var json = this.json;
      var extensions = this.extensions;
  
      var meshDef = json.meshes[meshIndex];
      var primitives = meshDef.primitives;
  
      var pending = [];
  
      for (var i = 0, il = primitives.length; i < il; i++) {
        var material =
          primitives[i].material === undefined
            ? createDefaultMaterial()
            : this.getDependency("material", primitives[i].material);
  
        pending.push(material);
      }
  
      return Promise.all(pending).then(function(originalMaterials) {
        return parser.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 (mesh.isSkinnedMesh === true) mesh.normalizeSkinWeights(); // #15319
  
              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;
  
            assignExtrasToUserData(mesh, meshDef);
  
            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 = parser.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
  
                  parser.cache.add(cacheKey, pointsMaterial);
                }
  
                material = pointsMaterial;
              } else if (mesh.isLine) {
                var cacheKey = "LineBasicMaterial:" + material.uuid;
  
                var lineMaterial = parser.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
  
                  parser.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 = parser.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;
  
                  parser.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;
  
      assignExtrasToUserData(camera, cameraDef);
  
      return Promise.resolve(camera);
    };
  
    /**
     * Specification: https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#skins
     * @param {number} skinIndex
     * @return {Promise<Object>}
     */
    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 = json.animations[animationIndex];
  
      var pendingNodes = [];
      var pendingInputAccessors = [];
      var pendingOutputAccessors = [];
      var pendingSamplers = [];
      var pendingTargets = [];
  
      for (var i = 0, il = animationDef.channels.length; i < il; i++) {
        var channel = animationDef.channels[i];
        var sampler = animationDef.samplers[channel.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;
  
        pendingNodes.push(this.getDependency("node", name));
        pendingInputAccessors.push(this.getDependency("accessor", input));
        pendingOutputAccessors.push(this.getDependency("accessor", output));
        pendingSamplers.push(sampler);
        pendingTargets.push(target);
      }
  
      return Promise.all([
        Promise.all(pendingNodes),
        Promise.all(pendingInputAccessors),
        Promise.all(pendingOutputAccessors),
        Promise.all(pendingSamplers),
        Promise.all(pendingTargets)
      ]).then(function(dependencies) {
        var nodes = dependencies[0];
        var inputAccessors = dependencies[1];
        var outputAccessors = dependencies[2];
        var samplers = dependencies[3];
        var targets = dependencies[4];
  
        var tracks = [];
  
        for (var i = 0, il = nodes.length; i < il; i++) {
          var node = nodes[i];
          var inputAccessor = inputAccessors[i];
          var outputAccessor = outputAccessors[i];
          var sampler = samplers[i];
          var target = targets[i];
  
          if (node === undefined) continue;
  
          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 parser = this;
  
      var meshReferences = json.meshReferences;
      var meshUses = json.meshUses;
  
      var nodeDef = json.nodes[nodeIndex];
  
      return (function() {
        // .isBone isn't in glTF spec. See .markDefs
        if (nodeDef.isBone === true) {
          return Promise.resolve(new THREE.Bone());
        } else if (nodeDef.mesh !== undefined) {
          return parser.getDependency("mesh", nodeDef.mesh).then(function(mesh) {
            var node;
  
            if (meshReferences[nodeDef.mesh] > 1) {
              var instanceNum = meshUses[nodeDef.mesh]++;
  
              node = mesh.clone();
              node.name += "_instance_" + instanceNum;
  
              // onBeforeRender copy for Specular-Glossiness
              node.onBeforeRender = mesh.onBeforeRender;
  
              for (var i = 0, il = node.children.length; i < il; i++) {
                node.children[i].name += "_instance_" + instanceNum;
                node.children[i].onBeforeRender = mesh.children[i].onBeforeRender;
              }
            } else {
              node = mesh;
            }
  
            // if weights are provided on the node, override weights on the mesh.
            if (nodeDef.weights !== undefined) {
              node.traverse(function(o) {
                if (!o.isMesh) return;
  
                for (var i = 0, il = nodeDef.weights.length; i < il; i++) {
                  o.morphTargetInfluences[i] = nodeDef.weights[i];
                }
              });
            }
  
            return node;
          });
        } else if (nodeDef.camera !== undefined) {
          return parser.getDependency("camera", nodeDef.camera);
        } else if (
          nodeDef.extensions &&
          nodeDef.extensions[EXTENSIONS.KHR_LIGHTS_PUNCTUAL] &&
          nodeDef.extensions[EXTENSIONS.KHR_LIGHTS_PUNCTUAL].light !== undefined
        ) {
          return parser.getDependency(
            "light",
            nodeDef.extensions[EXTENSIONS.KHR_LIGHTS_PUNCTUAL].light
          );
        } else {
          return Promise.resolve(new THREE.Object3D());
        }
      })().then(function(node) {
        if (nodeDef.name !== undefined) {
          node.name = THREE.PropertyBinding.sanitizeNodeName(nodeDef.name);
        }
  
        assignExtrasToUserData(node, nodeDef);
  
        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, parser) {
        var nodeDef = json.nodes[nodeId];
  
        return parser
          .getDependency("node", nodeId)
          .then(function(node) {
            if (nodeDef.skin === undefined) return node;
  
            // build skeleton here as well
  
            var skinEntry;
  
            return parser
              .getDependency("skin", nodeDef.skin)
              .then(function(skin) {
                skinEntry = skin;
  
                var pendingJoints = [];
  
                for (var i = 0, il = skinEntry.joints.length; i < il; i++) {
                  pendingJoints.push(
                    parser.getDependency("node", skinEntry.joints[i])
                  );
                }
  
                return Promise.all(pendingJoints);
              })
              .then(function(jointNodes) {
                var meshes = node.isGroup === true ? node.children : [node];
  
                for (var i = 0, il = meshes.length; i < il; i++) {
                  var mesh = meshes[i];
  
                  var bones = [];
                  var boneInverses = [];
  
                  for (var j = 0, jl = jointNodes.length; j < jl; j++) {
                    var jointNode = jointNodes[j];
  
                    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.',
                        skinEntry.joints[j]
                      );
                    }
                  }
  
                  mesh.bind(
                    new THREE.Skeleton(bones, boneInverses),
                    mesh.matrixWorld
                  );
                }
  
                return node;
              });
          })
          .then(function(node) {
            // build node hierachy
  
            parentObject.add(node);
  
            var pending = [];
  
            if (nodeDef.children) {
              var children = nodeDef.children;
  
              for (var i = 0, il = children.length; i < il; i++) {
                var child = children[i];
                pending.push(buildNodeHierachy(child, node, json, parser));
              }
            }
  
            return Promise.all(pending);
          });
      }
  
      return function loadScene(sceneIndex) {
        var json = this.json;
        var extensions = this.extensions;
        var sceneDef = this.json.scenes[sceneIndex];
        var parser = this;
  
        var scene = new THREE.Scene();
        if (sceneDef.name !== undefined) scene.name = sceneDef.name;
  
        assignExtrasToUserData(scene, sceneDef);
  
        if (sceneDef.extensions)
          addUnknownExtensionsToUserData(extensions, scene, sceneDef);
  
        var nodeIds = sceneDef.nodes || [];
  
        var pending = [];
  
        for (var i = 0, il = nodeIds.length; i < il; i++) {
          pending.push(buildNodeHierachy(nodeIds[i], scene, json, parser));
        }
  
        return Promise.all(pending).then(function() {
          return scene;
        });
      };
    })();
  
    return GLTFLoader;
  })();
  
  module.exports = _GLTFLoader;
  