three.js/examples/js/loaders/UTF8Loader.js

/**
 * Loader for UTF8 version2 (after r51) encoded models generated by:
 *	http://code.google.com/p/webgl-loader/
 *
 * Code to load/decompress mesh is taken from r100 of this webgl-loader
 */

THREE.UTF8Loader = function () {};

/**
 * Load UTF8 encoded model
 * @param jsonUrl - URL from which to load json containing information about model
 * @param callback - Callback(THREE.Object3D) on successful loading of model
 * @param options - options on how to load model (see THREE.MTLLoader.MaterialCreator for basic options)
 *                  Additional options include
 *                   geometryBase: Base url from which to load referenced geometries
 *                   materialBase: Base url from which to load referenced textures
 */

THREE.UTF8Loader.prototype.load = function ( jsonUrl, callback, options ) {

    this.downloadModelJson( jsonUrl, options, callback );

};

// BufferGeometryCreator

THREE.UTF8Loader.BufferGeometryCreator = function () {
};

THREE.UTF8Loader.BufferGeometryCreator.prototype.create = function ( attribArray, indexArray ) {

	var ntris = indexArray.length / 3;

	var geometry = new THREE.BufferGeometry();

	var positionArray = new Float32Array( 3 * 3 * ntris );
	var normalArray = new Float32Array( 3 * 3 * ntris );
	var uvArray = new Float32Array( 2 * 3 * ntris );

	var i, j, offset;
	var x, y, z;
	var u, v;

	var end = attribArray.length;
	var stride = 8;

	// extract positions

	j = 0;
	offset = 0;

	for( i = offset; i < end; i += stride ) {

		x = attribArray[ i ];
		y = attribArray[ i + 1 ];
		z = attribArray[ i + 2 ];

		positionArray[ j++ ] = x;
		positionArray[ j++ ] = y;
		positionArray[ j++ ] = z;

	}

	// extract uvs

	j = 0;
	offset = 3;

	for( i = offset; i < end; i += stride ) {

		u = attribArray[ i ];
		v = attribArray[ i + 1 ];

		uvArray[ j++ ] = u;
		uvArray[ j++ ] = v;

	}

	// extract normals

	j = 0;
	offset = 5;

	for( i = offset; i < end; i += stride ) {

		x = attribArray[ i ];
		y = attribArray[ i + 1 ];
		z = attribArray[ i + 2 ];

		normalArray[ j++ ] = x;
		normalArray[ j++ ] = y;
		normalArray[ j++ ] = z;

	}

	// create attributes

	var attributes = geometry.attributes;

	attributes[ "index" ]    = { itemSize: 1, array: indexArray, numItems: indexArray.length };
	attributes[ "position" ] = { itemSize: 3, array: positionArray, numItems: positionArray.length };
	attributes[ "normal" ]   = { itemSize: 3, array: normalArray, numItems: normalArray.length };
	attributes[ "uv" ] 		 = { itemSize: 2, array: uvArray, numItems: uvArray.length };

	// create offsets
	// (all triangles should fit in a single chunk)

	geometry.offsets = [ { start: 0, count: indexArray.length, index: 0 } ];

	geometry.computeBoundingSphere();

	return geometry;

};

// GeometryCreator

THREE.UTF8Loader.GeometryCreator = function () {
};

THREE.UTF8Loader.GeometryCreator.prototype = {

    create: function ( attribArray, indexArray ) {

        var geometry = new THREE.Geometry();

        this.init_vertices( geometry, attribArray, 8, 0 );

        var uvs = this.init_uvs( attribArray, 8, 3 );
        var normals = this.init_normals( attribArray, 8, 5 );

        this.init_faces( geometry, normals, uvs, indexArray );

        geometry.computeCentroids();
        geometry.computeFaceNormals();

        return geometry;

    },

    init_vertices: function ( scope, data, stride, offset ) {

        var i, x, y, z;
		var end = data.length;

        for( i = offset; i < end; i += stride ) {

            x = data[ i ];
            y = data[ i + 1 ];
            z = data[ i + 2 ];

            this.addVertex( scope, x, y, z );

        }

    },

    init_normals: function( data, stride, offset ) {

        var normals = [];

        var i, x, y, z;
		var end = data.length;

        for( i = offset; i < end; i += stride ) {

            // Assumes already normalized to <-1,1> (unlike previous version of UTF8Loader)

            x = data[ i ];
            y = data[ i + 1 ];
            z = data[ i + 2 ];

            normals.push( x, y, z );

        }

        return normals;

    },

    init_uvs: function( data, stride, offset ) {

        var uvs = [];

        var i, u, v;
		var end = data.length;

        for( i = offset; i < end; i += stride ) {

            // Assumes uvs are already normalized (unlike previous version of UTF8Loader)
            // uvs can be negative, need to set wrap for texture map later on ...

            u = data[ i ];
            v = data[ i + 1 ];

            uvs.push( u, v );
        }

        return uvs;

    },

    init_faces: function( scope, normals, uvs, indices ) {

        var i,
            a, b, c,
            u1, v1, u2, v2, u3, v3;

		var end = indices.length;

        var m = 0; // all faces defaulting to material 0

        for( i = 0; i < end; i += 3 ) {

            a = indices[ i ];
            b = indices[ i + 1 ];
            c = indices[ i + 2 ];

            this.f3n( scope, normals, a, b, c, m, a, b, c );

            u1 = uvs[ a * 2 ];
            v1 = uvs[ a * 2 + 1 ];

            u2 = uvs[ b * 2 ];
            v2 = uvs[ b * 2 + 1 ];

            u3 = uvs[ c * 2 ];
            v3 = uvs[ c * 2 + 1 ];

            this.uv3( scope.faceVertexUvs[ 0 ], u1, v1, u2, v2, u3, v3 );

        }

    },

    addVertex: function ( scope, x, y, z ) {

        scope.vertices.push( new THREE.Vector3( x, y, z ) );

    },

    f3n: function( scope, normals, a, b, c, mi, nai, nbi, nci ) {

        var nax = normals[ nai * 3 ],
            nay = normals[ nai * 3 + 1 ],
            naz = normals[ nai * 3 + 2 ],

            nbx = normals[ nbi * 3 ],
            nby = normals[ nbi * 3 + 1 ],
            nbz = normals[ nbi * 3 + 2 ],

            ncx = normals[ nci * 3 ],
            ncy = normals[ nci * 3 + 1 ],
            ncz = normals[ nci * 3 + 2 ];

        var na = new THREE.Vector3( nax, nay, naz ),
            nb = new THREE.Vector3( nbx, nby, nbz ),
            nc = new THREE.Vector3( ncx, ncy, ncz );

        scope.faces.push( new THREE.Face3( a, b, c, [ na, nb, nc ], null, mi ) );

    },

    uv3: function ( where, u1, v1, u2, v2, u3, v3 ) {

        var uv = [];
        uv.push( new THREE.UV( u1, v1 ) );
        uv.push( new THREE.UV( u2, v2 ) );
        uv.push( new THREE.UV( u3, v3 ) );
        where.push( uv );

    }

};


// UTF-8 decoder from webgl-loader (r100)
// http://code.google.com/p/webgl-loader/

// Model manifest description. Contains objects like:
// name: {
//   materials: { 'material_name': { ... } ... },
//   decodeParams: {
//     decodeOffsets: [ ... ],
//     decodeScales: [ ... ],
//   },
//   urls: {
//     'url': [
//       { material: 'material_name',
//         attribRange: [#, #],
//         indexRange: [#, #],
//         names: [ 'object names' ... ],
//         lengths: [#, #, # ... ]
//       }
//     ],
//     ...
//   }
// }

var DEFAULT_DECODE_PARAMS = {

    decodeOffsets: [-4095, -4095, -4095, 0, 0, -511, -511, -511],
    decodeScales: [1/8191, 1/8191, 1/8191, 1/1023, 1/1023, 1/1023, 1/1023, 1/1023]

    // TODO: normal decoding? (see walt.js)
    // needs to know: input, output (from vertex format!)
    //
    // Should split attrib/index.
    // 1) Decode position and non-normal attributes.
    // 2) Decode indices, computing normals
    // 3) Maybe normalize normals? Only necessary for refinement, or fixed?
    // 4) Maybe refine normals? Should this be part of regular refinement?
    // 5) Morphing

};

// Triangle strips!

// TODO: will it be an optimization to specialize this method at
// runtime for different combinations of stride, decodeOffset and
// decodeScale?

THREE.UTF8Loader.prototype.decompressAttribsInner_ = function ( str, inputStart, inputEnd,
                                                                  output, outputStart, stride,
                                                                  decodeOffset, decodeScale ) {

    var prev = 0;

    for ( var j = inputStart; j < inputEnd; j ++ ) {

        var code = str.charCodeAt( j );
        prev += ( code >> 1 ) ^ ( -( code & 1 ) );

        output[ outputStart ] = decodeScale * ( prev + decodeOffset );
        outputStart += stride;

    }

};

THREE.UTF8Loader.prototype.decompressIndices_ = function( str, inputStart, numIndices,
                                                            output, outputStart ) {

	var highest = 0;

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

        var code = str.charCodeAt( inputStart ++ );

        output[ outputStart ++ ] = highest - code;

        if ( code === 0 ) {

            highest ++;

        }

    }

};

THREE.UTF8Loader.prototype.decompressAABBs_ = function ( str, inputStart, numBBoxen,
                                                           decodeOffsets, decodeScales ) {
    var numFloats = 6 * numBBoxen;

    var inputEnd = inputStart + numFloats;
    var outputStart = 0;

    var bboxen = new Float32Array( numFloats );

    for ( var i = inputStart; i < inputEnd; i += 6 ) {

        var minX = str.charCodeAt(i + 0) + decodeOffsets[0];
        var minY = str.charCodeAt(i + 1) + decodeOffsets[1];
        var minZ = str.charCodeAt(i + 2) + decodeOffsets[2];

        var radiusX = (str.charCodeAt(i + 3) + 1) >> 1;
        var radiusY = (str.charCodeAt(i + 4) + 1) >> 1;
        var radiusZ = (str.charCodeAt(i + 5) + 1) >> 1;

        bboxen[ outputStart++ ] = decodeScales[0] * (minX + radiusX);
        bboxen[ outputStart++ ] = decodeScales[1] * (minY + radiusY);
        bboxen[ outputStart++ ] = decodeScales[2] * (minZ + radiusZ);

        bboxen[ outputStart++ ] = decodeScales[0] * radiusX;
        bboxen[ outputStart++ ] = decodeScales[1] * radiusY;
        bboxen[ outputStart++ ] = decodeScales[2] * radiusZ;

    }

    return bboxen;

};

THREE.UTF8Loader.prototype.decompressMesh =  function ( str, meshParams, decodeParams, name, idx, callback ) {

    // Extract conversion parameters from attribArrays.

    var stride = decodeParams.decodeScales.length;

    var decodeOffsets = decodeParams.decodeOffsets;
    var decodeScales = decodeParams.decodeScales;

    var attribStart = meshParams.attribRange[0];
    var numVerts = meshParams.attribRange[1];

    // Decode attributes.

    var inputOffset = attribStart;
    var attribsOut = new Float32Array( stride * numVerts );

    for (var j = 0; j < stride; j ++ ) {

        var end = inputOffset + numVerts;

		var decodeScale = decodeScales[j];

        if ( decodeScale ) {

            // Assume if decodeScale is never set, simply ignore the
            // attribute.

            this.decompressAttribsInner_( str, inputOffset, end,
                attribsOut, j, stride,
                decodeOffsets[j], decodeScale );
        }

        inputOffset = end;

    }

    var indexStart = meshParams.indexRange[ 0 ];
    var numIndices = 3 * meshParams.indexRange[ 1 ];

    var indicesOut = new Uint16Array( numIndices );

    this.decompressIndices_( str, inputOffset, numIndices, indicesOut, 0 );

    // Decode bboxen.

    var bboxen = undefined;
    var bboxOffset = meshParams.bboxes;

    if ( bboxOffset ) {

        bboxen = this.decompressAABBs_( str, bboxOffset, meshParams.names.length, decodeOffsets, decodeScales );
    }

    callback( name, idx, attribsOut, indicesOut, bboxen, meshParams );

};

THREE.UTF8Loader.prototype.copyAttrib = function ( stride, attribsOutFixed, lastAttrib, index ) {

    for ( var j = 0; j < stride; j ++ ) {

        lastAttrib[ j ] = attribsOutFixed[ stride * index + j ];

    }

};

THREE.UTF8Loader.prototype.decodeAttrib2 = function ( str, stride, decodeOffsets, decodeScales, deltaStart,
                                                        numVerts, attribsOut, attribsOutFixed, lastAttrib,
                                                        index ) {

    for ( var j = 0; j < 5; j ++ ) {

        var code = str.charCodeAt( deltaStart + numVerts*j + index );
        var delta = ( code >> 1) ^ (-(code & 1));

        lastAttrib[ j ] += delta;
        attribsOutFixed[ stride * index + j ] = lastAttrib[ j ];
        attribsOut[ stride * index + j ] = decodeScales[ j ] * ( lastAttrib[ j ] + decodeOffsets[ j ] );
    }

};

THREE.UTF8Loader.prototype.accumulateNormal = function ( i0, i1, i2, attribsOutFixed, crosses ) {

    var p0x = attribsOutFixed[ 8*i0 ];
    var p0y = attribsOutFixed[ 8*i0 + 1 ];
    var p0z = attribsOutFixed[ 8*i0 + 2 ];

    var p1x = attribsOutFixed[ 8*i1 ];
    var p1y = attribsOutFixed[ 8*i1 + 1 ];
    var p1z = attribsOutFixed[ 8*i1 + 2 ];

    var p2x = attribsOutFixed[ 8*i2 ];
    var p2y = attribsOutFixed[ 8*i2 + 1 ];
    var p2z = attribsOutFixed[ 8*i2 + 2 ];

    p1x -= p0x;
    p1y -= p0y;
    p1z -= p0z;

    p2x -= p0x;
    p2y -= p0y;
    p2z -= p0z;

    p0x = p1y*p2z - p1z*p2y;
    p0y = p1z*p2x - p1x*p2z;
    p0z = p1x*p2y - p1y*p2x;

    crosses[ 3*i0 ]     += p0x;
    crosses[ 3*i0 + 1 ] += p0y;
    crosses[ 3*i0 + 2 ] += p0z;

    crosses[ 3*i1 ]     += p0x;
    crosses[ 3*i1 + 1 ] += p0y;
    crosses[ 3*i1 + 2 ] += p0z;

    crosses[ 3*i2 ]     += p0x;
    crosses[ 3*i2 + 1 ] += p0y;
    crosses[ 3*i2 + 2 ] += p0z;

};

THREE.UTF8Loader.prototype.decompressMesh2 = function( str, meshParams, decodeParams, name, idx, callback ) {

    var MAX_BACKREF = 96;

    // Extract conversion parameters from attribArrays.

    var stride = decodeParams.decodeScales.length;

	var decodeOffsets = decodeParams.decodeOffsets;
    var decodeScales = decodeParams.decodeScales;

    var deltaStart = meshParams.attribRange[ 0 ];
    var numVerts = meshParams.attribRange[ 1 ];

    var codeStart = meshParams.codeRange[ 0 ];
    var codeLength = meshParams.codeRange[ 1 ];

    var numIndices = 3 * meshParams.codeRange[ 2 ];

    var indicesOut = new Uint16Array( numIndices );

    var crosses = new Int32Array( 3 * numVerts );

    var lastAttrib = new Uint16Array( stride );

    var attribsOutFixed = new Uint16Array( stride * numVerts );
    var attribsOut = new Float32Array( stride * numVerts );

    var highest = 0;
    var outputStart = 0;

    for ( var i = 0; i < numIndices; i += 3 ) {

        var code = str.charCodeAt( codeStart ++ );

        var max_backref = Math.min( i, MAX_BACKREF );

        if ( code < max_backref ) {

            // Parallelogram

            var winding = code % 3;
            var backref = i - ( code - winding );
            var i0, i1, i2;

            switch ( winding ) {

                case 0:

                    i0 = indicesOut[ backref + 2 ];
                    i1 = indicesOut[ backref + 1 ];
                    i2 = indicesOut[ backref + 0 ];
                    break;

                case 1:

                    i0 = indicesOut[ backref + 0 ];
                    i1 = indicesOut[ backref + 2 ];
                    i2 = indicesOut[ backref + 1 ];
                    break;

                case 2:

                    i0 = indicesOut[ backref + 1 ];
                    i1 = indicesOut[ backref + 0 ];
                    i2 = indicesOut[ backref + 2 ];
                    break;

            }

            indicesOut[ outputStart ++ ] = i0;
            indicesOut[ outputStart ++ ] = i1;

            code = str.charCodeAt( codeStart ++ );

            var index = highest - code;
            indicesOut[ outputStart ++ ] = index;

            if ( code === 0 ) {

                for (var j = 0; j < 5; j ++ ) {

                    var deltaCode = str.charCodeAt( deltaStart + numVerts * j + highest );

                    var prediction = ((deltaCode >> 1) ^ (-(deltaCode & 1))) +
                        attribsOutFixed[stride*i0 + j] +
                        attribsOutFixed[stride*i1 + j] -
                        attribsOutFixed[stride*i2 + j];

                    lastAttrib[j] = prediction;

                    attribsOutFixed[ stride * highest + j ] = prediction;
                    attribsOut[ stride * highest + j ] = decodeScales[ j ] * ( prediction + decodeOffsets[ j ] );

                }

                highest ++;

            } else {

                this.copyAttrib( stride, attribsOutFixed, lastAttrib, index );

            }

            this.accumulateNormal( i0, i1, index, attribsOutFixed, crosses );

        } else {

            // Simple

            var index0 = highest - ( code - max_backref );

            indicesOut[ outputStart ++ ] = index0;

            if ( code === max_backref ) {

                this.decodeAttrib2( str, stride, decodeOffsets, decodeScales, deltaStart,
                    numVerts, attribsOut, attribsOutFixed, lastAttrib,
                    highest ++ );

            } else {

                this.copyAttrib(stride, attribsOutFixed, lastAttrib, index0);

            }

            code = str.charCodeAt( codeStart ++ );

            var index1 = highest - code;
            indicesOut[ outputStart ++ ] = index1;

            if ( code === 0 ) {

                this.decodeAttrib2( str, stride, decodeOffsets, decodeScales, deltaStart,
                    numVerts, attribsOut, attribsOutFixed, lastAttrib,
                    highest ++ );

            } else {

                this.copyAttrib( stride, attribsOutFixed, lastAttrib, index1 );

            }

            code = str.charCodeAt( codeStart ++ );

            var index2 = highest - code;
            indicesOut[ outputStart ++ ] = index2;

            if ( code === 0 ) {

                for ( var j = 0; j < 5; j ++ ) {

                    lastAttrib[ j ] = ( attribsOutFixed[ stride * index0 + j ] + attribsOutFixed[ stride * index1 + j ] ) / 2;

                }

                this.decodeAttrib2( str, stride, decodeOffsets, decodeScales, deltaStart,
                    numVerts, attribsOut, attribsOutFixed, lastAttrib,
                    highest ++ );

            } else {

                this.copyAttrib( stride, attribsOutFixed, lastAttrib, index2 );

            }

            this.accumulateNormal( index0, index1, index2, attribsOutFixed, crosses );

        }

    }

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

        var nx = crosses[ 3*i ];
        var ny = crosses[ 3*i + 1 ];
        var nz = crosses[ 3*i + 2 ];

        var norm = 511.0 / Math.sqrt( nx*nx + ny*ny + nz*nz );

        var cx = str.charCodeAt( deltaStart + 5*numVerts + i );
        var cy = str.charCodeAt( deltaStart + 6*numVerts + i );
        var cz = str.charCodeAt( deltaStart + 7*numVerts + i );

        attribsOut[ stride*i + 5 ] = norm*nx + ((cx >> 1) ^ (-(cx & 1)));
        attribsOut[ stride*i + 6 ] = norm*ny + ((cy >> 1) ^ (-(cy & 1)));
        attribsOut[ stride*i + 7 ] = norm*nz + ((cz >> 1) ^ (-(cz & 1)));
    }

    callback( name, idx, attribsOut, indicesOut, undefined, meshParams );

};

THREE.UTF8Loader.prototype.downloadMesh = function ( path, name, meshEntry, decodeParams, callback ) {

    var loader = this;
    var idx = 0;

    function onprogress( req, e ) {

        while ( idx < meshEntry.length ) {

            var meshParams = meshEntry[ idx ];
            var indexRange = meshParams.indexRange;

            if ( indexRange ) {

                var meshEnd = indexRange[ 0 ] + 3 * indexRange[ 1 ];

                if ( req.responseText.length < meshEnd ) break;

                loader.decompressMesh( req.responseText, meshParams, decodeParams, name, idx, callback );

            } else {

                var codeRange = meshParams.codeRange;
                var meshEnd = codeRange[ 0 ] + codeRange[ 1 ];

                if ( req.responseText.length < meshEnd ) break;

                loader.decompressMesh2( req.responseText, meshParams, decodeParams, name, idx, callback );
            }

            ++idx;

        }

    };

    getHttpRequest( path, function( req, e ) {

        if ( req.status === 200 || req.status === 0 ) {

            onprogress( req, e );

        }

        // TODO: handle errors.

    }, onprogress );

};

THREE.UTF8Loader.prototype.downloadMeshes = function ( path, meshUrlMap, decodeParams, callback ) {

    for ( var url in meshUrlMap ) {

        var meshEntry = meshUrlMap[url];
        this.downloadMesh( path + url, url, meshEntry, decodeParams, callback );

    }

};

THREE.UTF8Loader.prototype.createMeshCallback = function( materialBaseUrl, loadModelInfo, allDoneCallback ) {

	var nCompletedUrls = 0;
    var nExpectedUrls = 0;

    var expectedMeshesPerUrl = {};
    var decodedMeshesPerUrl = {};

	var modelParts = {};

	var meshUrlMap = loadModelInfo.urls;

    for ( var url in meshUrlMap ) {

        expectedMeshesPerUrl[ url ] = meshUrlMap[ url ].length;
        decodedMeshesPerUrl[ url ] = 0;

		nExpectedUrls ++;

        modelParts[ url ] = new THREE.Object3D();

    }

    var model = new THREE.Object3D();

    // Prepare materials first...

    var materialCreator = new THREE.MTLLoader.MaterialCreator( materialBaseUrl, loadModelInfo.options );
    materialCreator.setMaterials( loadModelInfo.materials );

    materialCreator.preload();

	// Create callback for creating mesh parts

    var geometryCreator = new THREE.UTF8Loader.GeometryCreator();
	var bufferGeometryCreator = new THREE.UTF8Loader.BufferGeometryCreator();

	var meshCallback = function( name, idx, attribArray, indexArray, bboxen, meshParams ) {

        // Got ourselves a new mesh

        // name identifies this part of the model (url)
        // idx is the mesh index of this mesh of the part
        // attribArray defines the vertices
        // indexArray defines the faces
        // bboxen defines the bounding box
        // meshParams contains the material info

		var useBuffers = loadModelInfo.options.useBuffers !== undefined ? loadModelInfo.options.useBuffers : true;

		if ( useBuffers ) {

			var geometry = bufferGeometryCreator.create( attribArray, indexArray );

		} else {

			var geometry = geometryCreator.create( attribArray, indexArray );

		}

        var material = materialCreator.create( meshParams.material );

		var mesh = new THREE.Mesh( geometry, material );
        modelParts[ name ].add( mesh );

        //model.add(new THREE.Mesh(geometry, material));

        decodedMeshesPerUrl[ name ] ++;

        if ( decodedMeshesPerUrl[ name ] === expectedMeshesPerUrl[ name ] ) {

            nCompletedUrls ++;

            model.add( modelParts[ name ] );

            if ( nCompletedUrls === nExpectedUrls ) {

                // ALL DONE!!!

                allDoneCallback( model );

            }

        }

    };

	return meshCallback;

};

THREE.UTF8Loader.prototype.downloadModel = function ( geometryBase, materialBase, model, callback ) {

    var meshCallback = this.createMeshCallback( materialBase, model, callback );
    this.downloadMeshes( geometryBase, model.urls, model.decodeParams, meshCallback );

};

THREE.UTF8Loader.prototype.downloadModelJson = function ( jsonUrl, options, callback ) {

    getJsonRequest( jsonUrl, function( loaded ) {

        if ( ! loaded.decodeParams ) {

            if ( options && options.decodeParams ) {

                loaded.decodeParams = options.decodeParams;

            } else {

                loaded.decodeParams = DEFAULT_DECODE_PARAMS;

            }

        }

        loaded.options = options;

        var geometryBase = jsonUrl.substr( 0, jsonUrl.lastIndexOf( "/" ) + 1 );
        var materialBase = geometryBase;

        if ( options && options.geometryBase ) {

            geometryBase = options.geometryBase;

            if ( geometryBase.charAt( geometryBase.length - 1 ) !== "/" ) {

                geometryBase = geometryBase + "/";

            }

        }

        if ( options && options.materialBase ) {

            materialBase = options.materialBase;

            if ( materialBase.charAt( materialBase.length - 1 ) !== "/" ) {

                materialBase = materialBase  + "/";

            }

        }

        this.downloadModel( geometryBase, materialBase, loaded, callback );

    }.bind( this ) );

};

// XMLHttpRequest stuff

function getHttpRequest( url, onload, opt_onprogress ) {

    var LISTENERS = {

        load: function( e ) { onload( req, e ); },
        progress: function( e ) { opt_onprogress( req, e ); }

    };

    var req = new XMLHttpRequest();
    addListeners( req, LISTENERS );

    req.open( 'GET', url, true );
    req.send( null );
}

function getJsonRequest( url, onjson ) {

    getHttpRequest( url,
        function( e ) { onjson( JSON.parse( e.responseText ) ); },
        function() {} );

}

function addListeners( dom, listeners ) {

    // TODO: handle event capture, object binding.

    for ( var key in listeners ) {

        dom.addEventListener( key, listeners[ key ] );

    }
}