text: /**
   * @author Don McCurdy / https://www.donmccurdy.com
   * @author Austin Eng / https://github.com/austinEng
   * @author Shrek Shao / https://github.com/shrekshao
   * @author Senya Pugach / https://upisfr.ee
   */
  
  import {
  	CompressedTexture,
  	FileLoader,
  	LinearFilter,
  	LinearMipmapLinearFilter,
  	Loader,
  	RGBA_ASTC_4x4_Format,
  	RGBA_BPTC_Format,
  	RGBA_PVRTC_4BPPV1_Format,
  	RGB_ETC1_Format,
  	RGB_PVRTC_4BPPV1_Format,
  	UnsignedByteType
  } from "../../../build/three.module.js";
  
  /**
   * Loader for Basis Universal GPU Texture Codec.
   *
   * Basis Universal is a "supercompressed" GPU texture and texture video
   * compression system that outputs a highly compressed intermediate file format
   * (.basis) that can be quickly transcoded to a wide variety of GPU texture
   * compression formats.
   *
   * This loader parallelizes the transcoding process across a configurable number
   * of web workers, before transferring the transcoded compressed texture back
   * to the main thread.
   */
  var BasisTextureLoader = function ( manager ) {
  
  	Loader.call( this, manager );
  
  	this.transcoderPath = '';
  	this.transcoderBinary = null;
  	this.transcoderPending = null;
  
  	this.workerLimit = 4;
  	this.workerPool = [];
  	this.workerNextTaskID = 1;
  	this.workerSourceURL = '';
  	this.workerConfig = {
  		format: null,
  		astcSupported: false,
  		bptcSupported: false,
  		etcSupported: false,
  		dxtSupported: false,
  		pvrtcSupported: false,
  	};
  
  };
  
  BasisTextureLoader.taskCache = new WeakMap();
  
  BasisTextureLoader.prototype = Object.assign( Object.create( Loader.prototype ), {
  
  	constructor: BasisTextureLoader,
  
  	setTranscoderPath: function ( path ) {
  
  		this.transcoderPath = path;
  
  		return this;
  
  	},
  
  	setWorkerLimit: function ( workerLimit ) {
  
  		this.workerLimit = workerLimit;
  
  		return this;
  
  	},
  
  	detectSupport: function ( renderer ) {
  
  		var config = this.workerConfig;
  
  		config.astcSupported = !! renderer.extensions.get( 'WEBGL_compressed_texture_astc' );
  		config.bptcSupported = !! renderer.extensions.get( 'EXT_texture_compression_bptc' );
  		config.etcSupported = !! renderer.extensions.get( 'WEBGL_compressed_texture_etc1' );
  		config.dxtSupported = !! renderer.extensions.get( 'WEBGL_compressed_texture_s3tc' );
  		config.pvrtcSupported = !! renderer.extensions.get( 'WEBGL_compressed_texture_pvrtc' )
  			|| !! renderer.extensions.get( 'WEBKIT_WEBGL_compressed_texture_pvrtc' );
  
  		if ( config.astcSupported ) {
  
  			config.format = BasisTextureLoader.BASIS_FORMAT.cTFASTC_4x4;
  
  		} else if ( config.bptcSupported ) {
  
  			config.format = BasisTextureLoader.BASIS_FORMAT.cTFBC7_M5;
  
  		} else if ( config.dxtSupported ) {
  
  			config.format = BasisTextureLoader.BASIS_FORMAT.cTFBC3;
  
  		} else if ( config.pvrtcSupported ) {
  
  			config.format = BasisTextureLoader.BASIS_FORMAT.cTFPVRTC1_4_RGBA;
  
  		} else if ( config.etcSupported ) {
  
  			config.format = BasisTextureLoader.BASIS_FORMAT.cTFETC1;
  
  		} else {
  
  			throw new Error( 'THREE.BasisTextureLoader: No suitable compressed texture format found.' );
  
  		}
  
  		return this;
  
  	},
  
  	load: function ( url, onLoad, onProgress, onError ) {
  
  		var loader = new FileLoader( this.manager );
  
  		loader.setResponseType( 'arraybuffer' );
  
  		loader.load( url, ( buffer ) => {
  
  			// Check for an existing task using this buffer. A transferred buffer cannot be transferred
  			// again from this thread.
  			if ( BasisTextureLoader.taskCache.has( buffer ) ) {
  
  				var cachedTask = BasisTextureLoader.taskCache.get( buffer );
  
  				return cachedTask.promise.then( onLoad ).catch( onError );
  
  			}
  
  			this._createTexture( buffer, url )
  				.then( onLoad )
  				.catch( onError );
  
  		}, onProgress, onError );
  
  	},
  
  	/**
  	 * @param	{ArrayBuffer} buffer
  	 * @param	{string} url
  	 * @return {Promise<CompressedTexture>}
  	 */
  	_createTexture: function ( buffer, url ) {
  
  		var worker;
  		var taskID;
  
  		var taskCost = buffer.byteLength;
  
  		var texturePending = this._allocateWorker( taskCost )
  			.then( ( _worker ) => {
  
  				worker = _worker;
  				taskID = this.workerNextTaskID ++;
  
  				return new Promise( ( resolve, reject ) => {
  
  					worker._callbacks[ taskID ] = { resolve, reject };
  
  					worker.postMessage( { type: 'transcode', id: taskID, buffer }, [ buffer ] );
  
  				} );
  
  			} )
  			.then( ( message ) => {
  
  				var config = this.workerConfig;
  
  				var { width, height, mipmaps, format } = message;
  
  				var texture;
  
  				switch ( format ) {
  
  					case BasisTextureLoader.BASIS_FORMAT.cTFASTC_4x4:
  						texture = new CompressedTexture( mipmaps, width, height, RGBA_ASTC_4x4_Format );
  						break;
  					case BasisTextureLoader.BASIS_FORMAT.cTFBC7_M5:
  						texture = new CompressedTexture( mipmaps, width, height, RGBA_BPTC_Format );
  						break;
  					case BasisTextureLoader.BASIS_FORMAT.cTFBC1:
  					case BasisTextureLoader.BASIS_FORMAT.cTFBC3:
  						texture = new CompressedTexture( mipmaps, width, height, BasisTextureLoader.DXT_FORMAT_MAP[ config.format ], UnsignedByteType );
  						break;
  					case BasisTextureLoader.BASIS_FORMAT.cTFETC1:
  						texture = new CompressedTexture( mipmaps, width, height, RGB_ETC1_Format );
  						break;
  					case BasisTextureLoader.BASIS_FORMAT.cTFPVRTC1_4_RGB:
  						texture = new CompressedTexture( mipmaps, width, height, RGB_PVRTC_4BPPV1_Format );
  						break;
  					case BasisTextureLoader.BASIS_FORMAT.cTFPVRTC1_4_RGBA:
  						texture = new CompressedTexture( mipmaps, width, height, RGBA_PVRTC_4BPPV1_Format );
  						break;
  					default:
  						throw new Error( 'THREE.BasisTextureLoader: No supported format available.' );
  
  				}
  
  				texture.minFilter = mipmaps.length === 1 ? LinearFilter : LinearMipmapLinearFilter;
  				texture.magFilter = LinearFilter;
  				texture.generateMipmaps = false;
  				texture.needsUpdate = true;
  
  				return texture;
  
  			} );
  
  		// Note: replaced '.finally()' with '.catch().then()' block - iOS 11 support (#19416)
  		texturePending
  			.catch( () => true )
  			.then( () => {
  
  				if ( worker && taskID ) {
  
  					worker._taskLoad -= taskCost;
  					delete worker._callbacks[ taskID ];
  
  				}
  
  			} );
  
  		// Cache the task result.
  		BasisTextureLoader.taskCache.set( buffer, {
  
  			url: url,
  			promise: texturePending
  
  		} );
  
  		return texturePending;
  
  	},
  
  	_initTranscoder: function () {
  
  		if ( ! this.transcoderPending ) {
  
  			// Load transcoder wrapper.
  			var jsLoader = new FileLoader( this.manager );
  			jsLoader.setPath( this.transcoderPath );
  			var jsContent = new Promise( ( resolve, reject ) => {
  
  				jsLoader.load( 'basis_transcoder.js', resolve, undefined, reject );
  
  			} );
  
  			// Load transcoder WASM binary.
  			var binaryLoader = new FileLoader( this.manager );
  			binaryLoader.setPath( this.transcoderPath );
  			binaryLoader.setResponseType( 'arraybuffer' );
  			var binaryContent = new Promise( ( resolve, reject ) => {
  
  				binaryLoader.load( 'basis_transcoder.wasm', resolve, undefined, reject );
  
  			} );
  
  			this.transcoderPending = Promise.all( [ jsContent, binaryContent ] )
  				.then( ( [ jsContent, binaryContent ] ) => {
  
  					var fn = BasisTextureLoader.BasisWorker.toString();
  
  					var body = [
  						'/* basis_transcoder.js */',
  						jsContent,
  						'/* worker */',
  						fn.substring( fn.indexOf( '{' ) + 1, fn.lastIndexOf( '}' ) )
  					].join( '\n' );
  
  					this.workerSourceURL = URL.createObjectURL( new Blob( [ body ] ) );
  					this.transcoderBinary = binaryContent;
  
  				} );
  
  		}
  
  		return this.transcoderPending;
  
  	},
  
  	_allocateWorker: function ( taskCost ) {
  
  		return this._initTranscoder().then( () => {
  
  			if ( this.workerPool.length < this.workerLimit ) {
  
  				var worker = new Worker( this.workerSourceURL );
  
  				worker._callbacks = {};
  				worker._taskLoad = 0;
  
  				worker.postMessage( {
  					type: 'init',
  					config: this.workerConfig,
  					transcoderBinary: this.transcoderBinary,
  				} );
  
  				worker.onmessage = function ( e ) {
  
  					var message = e.data;
  
  					switch ( message.type ) {
  
  						case 'transcode':
  							worker._callbacks[ message.id ].resolve( message );
  							break;
  
  						case 'error':
  							worker._callbacks[ message.id ].reject( message );
  							break;
  
  						default:
  							console.error( 'THREE.BasisTextureLoader: Unexpected message, "' + message.type + '"' );
  
  					}
  
  				};
  
  				this.workerPool.push( worker );
  
  			} else {
  
  				this.workerPool.sort( function ( a, b ) {
  
  					return a._taskLoad > b._taskLoad ? - 1 : 1;
  
  				} );
  
  			}
  
  			var worker = this.workerPool[ this.workerPool.length - 1 ];
  
  			worker._taskLoad += taskCost;
  
  			return worker;
  
  		} );
  
  	},
  
  	dispose: function () {
  
  		for ( var i = 0; i < this.workerPool.length; i ++ ) {
  
  			this.workerPool[ i ].terminate();
  
  		}
  
  		this.workerPool.length = 0;
  
  		return this;
  
  	}
  
  } );
  
  /* CONSTANTS */
  
  BasisTextureLoader.BASIS_FORMAT = {
  	cTFETC1: 0,
  	cTFETC2: 1,
  	cTFBC1: 2,
  	cTFBC3: 3,
  	cTFBC4: 4,
  	cTFBC5: 5,
  	cTFBC7_M6_OPAQUE_ONLY: 6,
  	cTFBC7_M5: 7,
  	cTFPVRTC1_4_RGB: 8,
  	cTFPVRTC1_4_RGBA: 9,
  	cTFASTC_4x4: 10,
  	cTFATC_RGB: 11,
  	cTFATC_RGBA_INTERPOLATED_ALPHA: 12,
  	cTFRGBA32: 13,
  	cTFRGB565: 14,
  	cTFBGR565: 15,
  	cTFRGBA4444: 16,
  };
  
  // DXT formats, from:
  // http://www.khronos.org/registry/webgl/extensions/WEBGL_compressed_texture_s3tc/
  BasisTextureLoader.DXT_FORMAT = {
  	COMPRESSED_RGB_S3TC_DXT1_EXT: 0x83F0,
  	COMPRESSED_RGBA_S3TC_DXT1_EXT: 0x83F1,
  	COMPRESSED_RGBA_S3TC_DXT3_EXT: 0x83F2,
  	COMPRESSED_RGBA_S3TC_DXT5_EXT: 0x83F3,
  };
  BasisTextureLoader.DXT_FORMAT_MAP = {};
  BasisTextureLoader.DXT_FORMAT_MAP[ BasisTextureLoader.BASIS_FORMAT.cTFBC1 ] =
  	BasisTextureLoader.DXT_FORMAT.COMPRESSED_RGB_S3TC_DXT1_EXT;
  BasisTextureLoader.DXT_FORMAT_MAP[ BasisTextureLoader.BASIS_FORMAT.cTFBC3 ] =
  	BasisTextureLoader.DXT_FORMAT.COMPRESSED_RGBA_S3TC_DXT5_EXT;
  
  /* WEB WORKER */
  
  BasisTextureLoader.BasisWorker = function () {
  
  	var config;
  	var transcoderPending;
  	var _BasisFile;
  
  	onmessage = function ( e ) {
  
  		var message = e.data;
  
  		switch ( message.type ) {
  
  			case 'init':
  				config = message.config;
  				init( message.transcoderBinary );
  				break;
  
  			case 'transcode':
  				transcoderPending.then( () => {
  
  					try {
  
  						var { width, height, hasAlpha, mipmaps, format } = transcode( message.buffer );
  
  						var buffers = [];
  
  						for ( var i = 0; i < mipmaps.length; ++ i ) {
  
  							buffers.push( mipmaps[ i ].data.buffer );
  
  						}
  
  						self.postMessage( { type: 'transcode', id: message.id, width, height, hasAlpha, mipmaps, format }, buffers );
  
  					} catch ( error ) {
  
  						console.error( error );
  
  						self.postMessage( { type: 'error', id: message.id, error: error.message } );
  
  					}
  
  				} );
  				break;
  
  		}
  
  	};
  
  	function init( wasmBinary ) {
  
  		var BasisModule;
  		transcoderPending = new Promise( ( resolve ) => {
  
  			BasisModule = { wasmBinary, onRuntimeInitialized: resolve };
  			BASIS( BasisModule );
  
  		} ).then( () => {
  
  			var { BasisFile, initializeBasis } = BasisModule;
  
  			_BasisFile = BasisFile;
  
  			initializeBasis();
  
  		} );
  
  	}
  
  	function transcode( buffer ) {
  
  		var basisFile = new _BasisFile( new Uint8Array( buffer ) );
  
  		var width = basisFile.getImageWidth( 0, 0 );
  		var height = basisFile.getImageHeight( 0, 0 );
  		var levels = basisFile.getNumLevels( 0 );
  		var hasAlpha = basisFile.getHasAlpha();
  
  		function cleanup() {
  
  			basisFile.close();
  			basisFile.delete();
  
  		}
  
  		if ( ! hasAlpha ) {
  
  			switch ( config.format ) {
  
  				case 9: // Hardcoded: BasisTextureLoader.BASIS_FORMAT.cTFPVRTC1_4_RGBA
  					config.format = 8; // Hardcoded: BasisTextureLoader.BASIS_FORMAT.cTFPVRTC1_4_RGB;
  					break;
  				default:
  					break;
  
  			}
  
  		}
  
  		if ( ! width || ! height || ! levels ) {
  
  			cleanup();
  			throw new Error( 'THREE.BasisTextureLoader:	Invalid .basis file' );
  
  		}
  
  		if ( ! basisFile.startTranscoding() ) {
  
  			cleanup();
  			throw new Error( 'THREE.BasisTextureLoader: .startTranscoding failed' );
  
  		}
  
  		var mipmaps = [];
  
  		for ( var mip = 0; mip < levels; mip ++ ) {
  
  			var mipWidth = basisFile.getImageWidth( 0, mip );
  			var mipHeight = basisFile.getImageHeight( 0, mip );
  			var dst = new Uint8Array( basisFile.getImageTranscodedSizeInBytes( 0, mip, config.format ) );
  
  			var status = basisFile.transcodeImage(
  				dst,
  				0,
  				mip,
  				config.format,
  				0,
  				hasAlpha
  			);
  
  			if ( ! status ) {
  
  				cleanup();
  				throw new Error( 'THREE.BasisTextureLoader: .transcodeImage failed.' );
  
  			}
  
  			mipmaps.push( { data: dst, width: mipWidth, height: mipHeight } );
  
  		}
  
  		cleanup();
  
  		return { width, height, hasAlpha, mipmaps, format: config.format };
  
  	}
  
  };
  
  export { BasisTextureLoader };
  