<!-- RUBY-BACKUP · part 14 -->
ototype.copy.call( lineMaterial, material );
					lineMaterial.color.copy( material.color );
					this.cache.add( cacheKey, lineMaterial );

				}

				material = lineMaterial;

			} // Clone the material if it will be modified


			if ( useVertexTangents || useVertexColors || useFlatShading || useSkinning || useMorphTargets ) {

				let cacheKey = 'ClonedMaterial:' + material.uuid + ':';
				if ( material.isGLTFSpecularGlossinessMaterial ) cacheKey += 'specular-glossiness:';
				if ( useSkinning ) cacheKey += 'skinning:';
				if ( useVertexTangents ) cacheKey += 'vertex-tangents:';
				if ( useVertexColors ) cacheKey += 'vertex-colors:';
				if ( useFlatShading ) cacheKey += 'flat-shading:';
				if ( useMorphTargets ) cacheKey += 'morph-targets:';
				if ( useMorphNormals ) cacheKey += 'morph-normals:';
				let cachedMaterial = this.cache.get( cacheKey );

				if ( ! cachedMaterial ) {

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

					if ( useVertexTangents ) {

						cachedMaterial.vertexTangents = true; // https://github.com/mrdoob/three.js/issues/11438#issuecomment-507003995

						if ( cachedMaterial.normalScale ) cachedMaterial.normalScale.y *= - 1;
						if ( cachedMaterial.clearcoatNormalScale ) cachedMaterial.clearcoatNormalScale.y *= - 1;

					}

					this.cache.add( cacheKey, cachedMaterial );
					this.associations.set( cachedMaterial, this.associations.get( material ) );

				}

				material = cachedMaterial;

			} // workarounds for mesh and geometry


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

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

			}

			mesh.material = material;

		}

		getMaterialType( ) {

			return THREE.MeshStandardMaterial;

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


		loadMaterial( materialIndex ) {

			const parser = this;
			const json = this.json;
			const extensions = this.extensions;
			const materialDef = json.materials[ materialIndex ];
			let materialType;
			const materialParams = {};
			const materialExtensions = materialDef.extensions || {};
			const pending = [];

			if ( materialExtensions[ EXTENSIONS.KHR_MATERIALS_PBR_SPECULAR_GLOSSINESS ] ) {

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

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

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

			} else {

				// Specification:
				// https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#metallic-roughness-material
				const metallicRoughness = materialDef.pbrMetallicRoughness || {};
				materialParams.color = new THREE.Color( 1.0, 1.0, 1.0 );
				materialParams.opacity = 1.0;

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

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

				}

				if ( metallicRoughness.baseColorTexture !== undefined ) {

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

				}

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

				if ( metallicRoughness.metallicRoughnessTexture !== undefined ) {

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

				}

				materialType = this._invokeOne( function ( ext ) {

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

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

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

				} ) ) );

			}

			if ( materialDef.doubleSided === true ) {

				materialParams.side = THREE.DoubleSide;

			}

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

			if ( alphaMode === ALPHA_MODES.BLEND ) {