three.js/examples/js/loaders/CompressedTextureLoader.js

/*
 * @author mrdoob / http://mrdoob.com/
 *
 * Abstract Base class to block based textures loader (dds, pvr, ...) 
 */

THREE.CompressedTextureLoader = function () {
	// override in sub classes
	this._parser = null;
};


THREE.CompressedTextureLoader.prototype = {

	constructor: THREE.CompressedTextureLoader,

	load: function ( url, onLoad, onError ) {

		var scope = this;

		var images = [];

		var texture = new THREE.CompressedTexture();
		texture.image = images;

		// no flipping for cube textures
		// (also flipping doesn't work for compressed textures )

		texture.flipY = false;

		// can't generate mipmaps for compressed textures
		// mips must be embedded in DDS files

		texture.generateMipmaps = false;

		if ( url instanceof Array ) {

			var loaded = 0;

			var loader = new THREE.XHRLoader();
			loader.setResponseType( 'arraybuffer' );

			var loadTexture = function ( i ) {
		
				loader.load( url[ i ], function ( buffer ) {

					var texDatas = scope._parser( buffer, true );

					images[ i ] = {
						width: texDatas.width,
						height: texDatas.height,
						format: texDatas.format,
						mipmaps: texDatas.mipmaps
					}

					loaded += 1;

					if ( loaded === 6 ) {

						texture.format = texDatas.format;
						texture.needsUpdate = true;

						if ( onLoad ) onLoad( texture );

					}

				} );

			}

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

				loadTexture( i );

			}

		} else {

			// compressed cubemap texture stored in a single DDS file

			var loader = new THREE.XHRLoader();
			loader.setResponseType( 'arraybuffer' );
			loader.load( url, function ( buffer ) {

				var texDatas = scope._parser( buffer, true );

				if ( texDatas.isCubemap ) {

					var faces = texDatas.mipmaps.length / texDatas.mipmapCount;

					for ( var f = 0; f < faces; f ++ ) {

						images[ f ] = { mipmaps : [] };

						for ( var i = 0; i < texDatas.mipmapCount; i ++ ) {

							images[ f ].mipmaps.push( texDatas.mipmaps[ f * texDatas.mipmapCount + i ] );
							images[ f ].format = texDatas.format;
							images[ f ].width = texDatas.width;
							images[ f ].height = texDatas.height;

						}

					}

				} else {

					texture.image.width = texDatas.width;
					texture.image.height = texDatas.height;
					texture.mipmaps = texDatas.mipmaps;

				}

				texture.format = texDatas.format;
				texture.needsUpdate = true;

				if ( onLoad ) onLoad( texture );

			} );

		}

		return texture;

	}
	
};