three/src/extras/geometries/WireframeGeometry.js

JavaScript 3D library

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

THREE.WireframeGeometry = function ( geometry ) {

	THREE.BufferGeometry.call( this );

	var edge = [ 0, 0 ], hash = {};

	function sortFunction( a, b ) {

		return a - b;

	}

	var keys = [ 'a', 'b', 'c' ];

	if ( geometry instanceof THREE.Geometry ) {

		var vertices = geometry.vertices;
		var faces = geometry.faces;
		var numEdges = 0;

		// allocate maximal size
		var edges = new Uint32Array( 6 * faces.length );

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

			var face = faces[ i ];

			for ( var j = 0; j < 3; j ++ ) {

				edge[ 0 ] = face[ keys[ j ] ];
				edge[ 1 ] = face[ keys[ ( j + 1 ) % 3 ] ];
				edge.sort( sortFunction );

				var key = edge.toString();

				if ( hash[ key ] === undefined ) {

					edges[ 2 * numEdges ] = edge[ 0 ];
					edges[ 2 * numEdges + 1 ] = edge[ 1 ];
					hash[ key ] = true;
					numEdges ++;

				}

			}

		}

		var coords = new Float32Array( numEdges * 2 * 3 );

		for ( var i = 0, l = numEdges; i < l; i ++ ) {

			for ( var j = 0; j < 2; j ++ ) {

				var vertex = vertices[ edges [ 2 * i + j ] ];

				var index = 6 * i + 3 * j;
				coords[ index + 0 ] = vertex.x;
				coords[ index + 1 ] = vertex.y;
				coords[ index + 2 ] = vertex.z;

			}

		}

		this.addAttribute( 'position', new THREE.BufferAttribute( coords, 3 ) );

	} else if ( geometry instanceof THREE.BufferGeometry ) {

		if ( geometry.index !== null ) {

			// Indexed BufferGeometry

			var indices = geometry.index.array;
			var vertices = geometry.attributes.position;
			var groups = geometry.groups;
			var numEdges = 0;

			if ( groups.length === 0 ) {

				geometry.addGroup( 0, indices.length );

			}

			// allocate maximal size
			var edges = new Uint32Array( 2 * indices.length );

			for ( var o = 0, ol = groups.length; o < ol; ++ o ) {

				var group = groups[ o ];

				var start = group.start;
				var count = group.count;

				for ( var i = start, il = start + count; i < il; i += 3 ) {

					for ( var j = 0; j < 3; j ++ ) {

						edge[ 0 ] = indices[ i + j ];
						edge[ 1 ] = indices[ i + ( j + 1 ) % 3 ];
						edge.sort( sortFunction );

						var key = edge.toString();

						if ( hash[ key ] === undefined ) {

							edges[ 2 * numEdges ] = edge[ 0 ];
							edges[ 2 * numEdges + 1 ] = edge[ 1 ];
							hash[ key ] = true;
							numEdges ++;

						}

					}

				}

			}

			var coords = new Float32Array( numEdges * 2 * 3 );

			for ( var i = 0, l = numEdges; i < l; i ++ ) {

				for ( var j = 0; j < 2; j ++ ) {

					var index = 6 * i + 3 * j;
					var index2 = edges[ 2 * i + j ];

					coords[ index + 0 ] = vertices.getX( index2 );
					coords[ index + 1 ] = vertices.getY( index2 );
					coords[ index + 2 ] = vertices.getZ( index2 );

				}

			}

			this.addAttribute( 'position', new THREE.BufferAttribute( coords, 3 ) );

		} else {

			// non-indexed BufferGeometry

			var vertices = geometry.attributes.position.array;
			var numEdges = vertices.length / 3;
			var numTris = numEdges / 3;

			var coords = new Float32Array( numEdges * 2 * 3 );

			for ( var i = 0, l = numTris; i < l; i ++ ) {

				for ( var j = 0; j < 3; j ++ ) {

					var index = 18 * i + 6 * j;

					var index1 = 9 * i + 3 * j;
					coords[ index + 0 ] = vertices[ index1 ];
					coords[ index + 1 ] = vertices[ index1 + 1 ];
					coords[ index + 2 ] = vertices[ index1 + 2 ];

					var index2 = 9 * i + 3 * ( ( j + 1 ) % 3 );
					coords[ index + 3 ] = vertices[ index2 ];
					coords[ index + 4 ] = vertices[ index2 + 1 ];
					coords[ index + 5 ] = vertices[ index2 + 2 ];

				}

			}

			this.addAttribute( 'position', new THREE.BufferAttribute( coords, 3 ) );

		}

	}

};

THREE.WireframeGeometry.prototype = Object.create( THREE.BufferGeometry.prototype );
THREE.WireframeGeometry.prototype.constructor = THREE.WireframeGeometry;