/src/extras/plugins/ShadowMapPlugin.js

/**
 * @author alteredq / http://alteredqualia.com/
 */

THREE.ShadowMapPlugin = function ( ) {

	var _gl,
	_renderer,
	_depthMaterial, _depthMaterialMorph,

	_frustum = new THREE.Frustum(),
	_projScreenMatrix = new THREE.Matrix4();

	this.init = function ( renderer ) {

		_gl = renderer.context;
		_renderer = renderer;

		var depthShader = THREE.ShaderLib[ "depthRGBA" ];
		var depthUniforms = THREE.UniformsUtils.clone( depthShader.uniforms );

		_depthMaterial = new THREE.ShaderMaterial( { fragmentShader: depthShader.fragmentShader, vertexShader: depthShader.vertexShader, uniforms: depthUniforms } );
		_depthMaterialMorph = new THREE.ShaderMaterial( { fragmentShader: depthShader.fragmentShader, vertexShader: depthShader.vertexShader, uniforms: depthUniforms, morphTargets: true } );

		_depthMaterial._shadowPass = true;
		_depthMaterialMorph._shadowPass = true;

	};

	this.render = function ( scene, camera ) {

		if ( ! ( _renderer.shadowMapEnabled && _renderer.shadowMapAutoUpdate ) ) return;

		this.update( scene, camera );

	};

	this.update = function ( scene, camera ) {

		var i, il, j, jl,

		shadowMap, shadowMatrix, shadowCamera,
		program, buffer, material,
		webglObject, object, light,
		renderList,

		lights = scene.lights,
		fog = null;

		// set GL state for depth map

		_gl.clearColor( 1, 1, 1, 1 );
		_gl.disable( _gl.BLEND );
		if ( _renderer.shadowMapCullFrontFaces ) _gl.cullFace( _gl.FRONT );

		_renderer.setDepthTest( true );

		// render depth map

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

			light = lights[ i ];

			if ( ! light.castShadow ) continue;

			if ( ! light.shadowMap ) {

				var pars = { minFilter: THREE.LinearFilter, magFilter: THREE.LinearFilter, format: THREE.RGBAFormat };

				light.shadowMap = new THREE.WebGLRenderTarget( light.shadowMapWidth, light.shadowMapHeight, pars );
				light.shadowMapSize = new THREE.Vector2( light.shadowMapWidth, light.shadowMapHeight );

				light.shadowMatrix = new THREE.Matrix4();

			}

			if ( ! light.shadowCamera ) {

				if ( light instanceof THREE.SpotLight ) {

					light.shadowCamera = new THREE.PerspectiveCamera( light.shadowCameraFov, light.shadowMapWidth / light.shadowMapHeight, light.shadowCameraNear, light.shadowCameraFar );

				} else if ( light instanceof THREE.DirectionalLight ) {

					light.shadowCamera = new THREE.OrthographicCamera( light.shadowCameraLeft, light.shadowCameraRight, light.shadowCameraTop, light.shadowCameraBottom, light.shadowCameraNear, light.shadowCameraFar );

				} else {

					console.error( "Unsupported light type for shadow" );
					continue;

				}

				scene.add( light.shadowCamera );

				if ( _renderer.autoUpdateScene ) scene.updateMatrixWorld();

			}


			if ( light.shadowCameraVisible && ! light.cameraHelper ) {

				light.cameraHelper = new THREE.CameraHelper( light.shadowCamera );
				light.shadowCamera.add( light.cameraHelper );

			}

			shadowMap = light.shadowMap;
			shadowMatrix = light.shadowMatrix;
			shadowCamera = light.shadowCamera;

			shadowCamera.position.copy( light.matrixWorld.getPosition() );
			shadowCamera.lookAt( light.target.matrixWorld.getPosition() );
			shadowCamera.updateMatrixWorld();

			shadowCamera.matrixWorldInverse.getInverse( shadowCamera.matrixWorld );

			if ( light.cameraHelper ) light.cameraHelper.lines.visible = light.shadowCameraVisible;
			if ( light.shadowCameraVisible ) light.cameraHelper.update( light.shadowCamera );

			// compute shadow matrix

			shadowMatrix.set( 0.5, 0.0, 0.0, 0.5,
							  0.0, 0.5, 0.0, 0.5,
							  0.0, 0.0, 0.5, 0.5,
							  0.0, 0.0, 0.0, 1.0 );

			shadowMatrix.multiplySelf( shadowCamera.projectionMatrix );
			shadowMatrix.multiplySelf( shadowCamera.matrixWorldInverse );

			// render shadow map

			if ( ! shadowCamera._viewMatrixArray ) shadowCamera._viewMatrixArray = new Float32Array( 16 );
			shadowCamera.matrixWorldInverse.flattenToArray( shadowCamera._viewMatrixArray );

			if ( ! shadowCamera._projectionMatrixArray ) shadowCamera._projectionMatrixArray = new Float32Array( 16 );
			shadowCamera.projectionMatrix.flattenToArray( shadowCamera._projectionMatrixArray );

			_projScreenMatrix.multiply( shadowCamera.projectionMatrix, shadowCamera.matrixWorldInverse );
			_frustum.setFromMatrix( _projScreenMatrix );

			_renderer.setRenderTarget( shadowMap );
			_renderer.clear();

			// set matrices & frustum culling

			renderList = scene.__webglObjects;

			for ( j = 0, jl = renderList.length; j < jl; j ++ ) {

				webglObject = renderList[ j ];
				object = webglObject.object;

				webglObject.render = false;

				if ( object.visible && object.castShadow ) {

					if ( ! ( object instanceof THREE.Mesh ) || ! ( object.frustumCulled ) || _frustum.contains( object ) ) {

						object.matrixWorld.flattenToArray( object._objectMatrixArray );
						object._modelViewMatrix.multiplyToArray( shadowCamera.matrixWorldInverse, object.matrixWorld, object._modelViewMatrixArray );

						webglObject.render = true;

					}

				}

			}

			// render regular objects

			for ( j = 0, jl = renderList.length; j < jl; j ++ ) {

				webglObject = renderList[ j ];

				if ( webglObject.render ) {

					object = webglObject.object;
					buffer = webglObject.buffer;

					_renderer.setObjectFaces( object );

					if ( object.customDepthMaterial ) {

						material = object.customDepthMaterial;

					} else if ( object.geometry.morphTargets.length ) {

						material = _depthMaterialMorph;

					} else {

						material = _depthMaterial;

					}

					if ( buffer instanceof THREE.BufferGeometry ) {

						_renderer.renderBufferDirect( shadowCamera, lights, fog, material, buffer, object );

					} else {

						_renderer.renderBuffer( shadowCamera, lights, fog, material, buffer, object );

					}

				}

			}

			// set matrices and render immediate objects

			renderList = scene.__webglObjectsImmediate;

			for ( j = 0, jl = renderList.length; j < jl; j ++ ) {

				webglObject = renderList[ j ];
				object = webglObject.object;

				if ( object.visible && object.castShadow ) {

					if( object.matrixAutoUpdate ) {

						object.matrixWorld.flattenToArray( object._objectMatrixArray );

					}

					object._modelViewMatrix.multiplyToArray( shadowCamera.matrixWorldInverse, object.matrixWorld, object._modelViewMatrixArray );

					_renderer.renderImmediateObject( shadowCamera, lights, fog, _depthMaterial, object );

				}

			}

		}

		// restore GL state

		var clearColor = _renderer.getClearColor(),
		clearAlpha = _renderer.getClearAlpha();

		_gl.clearColor( clearColor.r, clearColor.g, clearColor.b, clearAlpha );
		_gl.enable( _gl.BLEND );
		if ( _renderer.shadowMapCullFrontFaces ) _gl.cullFace( _gl.BACK );

	};

};