three.js/src/renderers/webgl/WebGLObjects.js

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

THREE.WebGLObjects = function ( gl, properties, info ) {

	var geometries = new THREE.WebGLGeometries( gl, properties, info );

	//

	function update( object ) {

		// TODO: Avoid updating twice (when using shadowMap). Maybe add frame counter.

		var geometry = geometries.get( object );

		if ( object.geometry instanceof THREE.Geometry ) {

			geometry.updateFromObject( object );

		}

		var attributes = geometry.attributes;

		for ( var name in attributes ) {

			updateAttribute( attributes[ name ] );

		}

		// morph targets

		var morphAttributes = geometry.morphAttributes;

		for ( var name in morphAttributes ) {

			var array = morphAttributes[ name ];

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

				updateAttribute( array[ i ] );

			}

		}

		return geometry;

	}

	function updateAttribute( attribute ) {

		var bufferType;

		if ( attribute instanceof THREE.IndexBufferAttribute ) {

			bufferType = gl.ELEMENT_ARRAY_BUFFER;

		} else {

			bufferType = gl.ARRAY_BUFFER;

		}

		var data = ( attribute instanceof THREE.InterleavedBufferAttribute ) ? attribute.data : attribute;

		var attributeProperties = properties.get( data );

		if ( attributeProperties.__webglBuffer === undefined ) {

			createBuffer( attributeProperties, data, bufferType );

		} else if ( attributeProperties.version !== data.version ) {

			updateBuffer( attributeProperties, data, bufferType );

		}

	}

	function createBuffer( attributeProperties, data, bufferType ) {

		attributeProperties.__webglBuffer = gl.createBuffer();
		gl.bindBuffer( bufferType, attributeProperties.__webglBuffer );

		var usage = gl.STATIC_DRAW;

		if ( data instanceof THREE.DynamicBufferAttribute
			 || ( data instanceof THREE.InstancedBufferAttribute && data.dynamic === true )
			 || ( data instanceof THREE.InterleavedBuffer && data.dynamic === true ) ) {

			usage = gl.DYNAMIC_DRAW;

		}

		gl.bufferData( bufferType, data.array, usage );

		attributeProperties.version = data.version;

	}

	function updateBuffer( attributeProperties, data, bufferType ) {

		gl.bindBuffer( bufferType, attributeProperties.__webglBuffer );

		if ( data.updateRange === undefined || data.updateRange.count === - 1 ) {

			// Not using update ranges

			gl.bufferSubData( bufferType, 0, data.array );

		} else if ( data.updateRange.count === 0 ) {

			console.error( 'THREE.WebGLObjects.updateBuffer: using updateRange for THREE.DynamicBufferAttribute and marked as needsUpdate but count is 0, ensure you are using set methods or updating manually.' );

		} else {

			gl.bufferSubData( bufferType, data.updateRange.offset * data.array.BYTES_PER_ELEMENT,
							  data.array.subarray( data.updateRange.offset, data.updateRange.offset + data.updateRange.count ) );

			data.updateRange.count = 0; // reset range

		}

		attributeProperties.version = data.version;

	}

	function getAttributeBuffer( attribute ) {

		if ( attribute instanceof THREE.InterleavedBufferAttribute ) {

			return properties.get( attribute.data ).__webglBuffer;

		}

		return properties.get( attribute ).__webglBuffer;

	}

	function getWireframeAttribute( geometry ) {

		var property = properties.get( geometry );

		if ( property.wireframe !== undefined ) {

			return property.wireframe;

		}

		var indices = [];

		var attributes = geometry.attributes;

		var index = attributes.index;
		var position = attributes.position;

		// console.time( 'wireframe' );

		if ( index !== undefined ) {

			var edges = {};
			var array = index.array;

			for ( var i = 0, l = array.length; i < l; i += 3 ) {

				var a = array[ i + 0 ];
				var b = array[ i + 1 ];
				var c = array[ i + 2 ];

				if ( checkEdge( edges, a, b ) ) indices.push( a, b );
				if ( checkEdge( edges, b, c ) ) indices.push( b, c );
				if ( checkEdge( edges, c, a ) ) indices.push( c, a );

			}

		} else {

			var array = position.array;

			for ( var i = 0, l = ( array.length / 3 ) - 1; i < l; i += 3 ) {

				var a = i + 0;
				var b = i + 1;
				var c = i + 2;

				indices.push( a, b, b, c, c, a );

			}

		}

		// console.timeEnd( 'wireframe' );

		var TypeArray = position.count > 65535 ? Uint32Array : Uint16Array;
		var attribute = new THREE.IndexBufferAttribute( new TypeArray( indices ), 1 );

		updateAttribute( attribute );

		property.wireframe = attribute;

		return attribute;

	}

	function checkEdge( edges, a, b ) {

		var hash = a < b ? a + '_' + b : b + '_' + a;

		if ( edges.hasOwnProperty( hash ) ) return false;

		edges[ hash ] = 1;

		return true;

	}

	this.getAttributeBuffer = getAttributeBuffer;
	this.getWireframeAttribute = getWireframeAttribute;

	this.update = update;

};