three.js/examples/js/exporters/GeometryExporter.js

/**
 * @author mrdoob / http://mrdoob.com/
 */

THREE.GeometryExporter = function () {};

THREE.GeometryExporter.prototype = {

	constructor: THREE.GeometryExporter,

	parse: function ( geometry ) {

		var output = {
			metadata: {
				version: 4.0,
				type: 'geometry',
				generator: 'GeometryExporter'
			}
		};

		var vertices = [];

		for ( var i = 0; i < geometry.vertices.length; i ++ ) {

			var vertex = geometry.vertices[ i ];
			vertices.push( vertex.x, vertex.y, vertex.z );

		}

		var faces = [];
		var normals = [];
		var normalsHash = {};
		var colors = [];
		var colorsHash = {};
		var uvs = [];
		var uvsHash = {};

		for ( var i = 0; i < geometry.faces.length; i ++ ) {

			var face = geometry.faces[ i ];

			var hasMaterial = false; // face.materialIndex !== undefined;
			var hasFaceUv = false; // deprecated
			var hasFaceVertexUv = geometry.faceVertexUvs[ 0 ].length > 0;
			var hasFaceNormal = face.normal.length() > 0;
			var hasFaceVertexNormal = face.vertexNormals.length > 0;
			var hasFaceColor = face.color.r !== 1 || face.color.g !== 1 || face.color.b !== 1;
			var hasFaceVertexColor = face.vertexColors.length > 0;

			var faceType = 0;

			faceType = setBit( faceType, 0, 0 );
			faceType = setBit( faceType, 1, hasMaterial );
			faceType = setBit( faceType, 2, hasFaceUv );
			faceType = setBit( faceType, 3, hasFaceVertexUv );
			faceType = setBit( faceType, 4, hasFaceNormal );
			faceType = setBit( faceType, 5, hasFaceVertexNormal );
			faceType = setBit( faceType, 6, hasFaceColor );
			faceType = setBit( faceType, 7, hasFaceVertexColor );

			faces.push( faceType );
			faces.push( face.a, face.b, face.c );


			/*
			if ( hasMaterial ) {

				faces.push( face.materialIndex );

			}
			*/

			if ( hasFaceVertexUv ) {

				var faceVertexUvs = geometry.faceVertexUvs[ 0 ][ i ];

				faces.push(
					getUvIndex( faceVertexUvs[ 0 ] ),
					getUvIndex( faceVertexUvs[ 1 ] ),
					getUvIndex( faceVertexUvs[ 2 ] )
				);

			}

			if ( hasFaceNormal ) {

				faces.push( getNormalIndex( face.normal ) );

			}

			if ( hasFaceVertexNormal ) {

				var vertexNormals = face.vertexNormals;

				faces.push(
					getNormalIndex( vertexNormals[ 0 ] ),
					getNormalIndex( vertexNormals[ 1 ] ),
					getNormalIndex( vertexNormals[ 2 ] )
				);

			}

			if ( hasFaceColor ) {

				faces.push( getColorIndex( face.color ) );

			}

			if ( hasFaceVertexColor ) {

				var vertexColors = face.vertexColors;

				faces.push(
					getColorIndex( vertexColors[ 0 ] ),
					getColorIndex( vertexColors[ 1 ] ),
					getColorIndex( vertexColors[ 2 ] )
				);

			}

		}

		function setBit( value, position, enabled ) {

			return enabled ? value | ( 1 << position ) : value & ( ~ ( 1 << position) );

		}

		function getNormalIndex( normal ) {

			var hash = normal.x.toString() + normal.y.toString() + normal.z.toString();

			if ( normalsHash[ hash ] !== undefined ) {

				return normalsHash[ hash ];

			}

			normalsHash[ hash ] = normals.length / 3;
			normals.push( normal.x, normal.y, normal.z );

			return normalsHash[ hash ];

		}

		function getColorIndex( color ) {

			var hash = color.r.toString() + color.g.toString() + color.b.toString();

			if ( colorsHash[ hash ] !== undefined ) {

				return colorsHash[ hash ];

			}

			colorsHash[ hash ] = colors.length;
			colors.push( color.getHex() );

			return colorsHash[ hash ];

		}

		function getUvIndex( uv ) {

			var hash = uv.x.toString() + uv.y.toString();

			if ( uvsHash[ hash ] !== undefined ) {

				return uvsHash[ hash ];

			}

			uvsHash[ hash ] = uvs.length / 2;
			uvs.push( uv.x, uv.y );

			return uvsHash[ hash ];

		}

		output.vertices = vertices;
		output.normals = normals;
		if ( colors.length > 0 ) output.colors = colors;
		if ( uvs.length > 0 ) output.uvs = [ uvs ]; // temporal backward compatibility
		output.faces = faces;

		//

		return output;

	}

};