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

THREE.DepthPassPlugin = function () {

	this.enabled = false;
	this.renderTarget = null;

	var _gl,
	_renderer,
	_depthMaterial, _depthMaterialMorph, _depthMaterialSkin, _depthMaterialMorphSkin,

	_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 } );
		_depthMaterialSkin = new THREE.ShaderMaterial( { fragmentShader: depthShader.fragmentShader, vertexShader: depthShader.vertexShader, uniforms: depthUniforms, skinning: true } );
		_depthMaterialMorphSkin = new THREE.ShaderMaterial( { fragmentShader: depthShader.fragmentShader, vertexShader: depthShader.vertexShader, uniforms: depthUniforms, morphTargets: true, skinning: true } );

		_depthMaterial._shadowPass = true;
		_depthMaterialMorph._shadowPass = true;
		_depthMaterialSkin._shadowPass = true;
		_depthMaterialMorphSkin._shadowPass = true;

	};

	this.render = function ( scene, camera ) {

		if ( ! this.enabled ) return;

		this.update( scene, camera );

	};

	this.update = function ( scene, camera ) {

		var i, il, j, jl, n,

		program, buffer, material,
		webglObject, object, light,
		renderList,

		fog = null;

		// set GL state for depth map

		_gl.clearColor( 1, 1, 1, 1 );
		_gl.disable( _gl.BLEND );

		_renderer.setDepthTest( true );

		// update scene

		if ( scene.autoUpdate === true ) scene.updateMatrixWorld();

		// update camera matrices and frustum

		camera.matrixWorldInverse.getInverse( camera.matrixWorld );

		_projScreenMatrix.multiplyMatrices( camera.projectionMatrix, camera.matrixWorldInverse );
		_frustum.setFromMatrix( _projScreenMatrix );

		// render depth map

		_renderer.setRenderTarget( this.renderTarget );
		_renderer.clear();

		// set object 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 ) {

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

					object._modelViewMatrix.multiplyMatrices( camera.matrixWorldInverse, object.matrixWorld );

					webglObject.render = true;

				}

			}

		}

		// render regular objects

		var objectMaterial, useMorphing, useSkinning;

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

			webglObject = renderList[ j ];

			if ( webglObject.render ) {

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

				// todo: create proper depth material for particles

				if ( object instanceof THREE.ParticleSystem && !object.customDepthMaterial ) continue;

				objectMaterial = getObjectMaterial( object );

				if ( objectMaterial ) _renderer.setMaterialFaces( object.material );

				useMorphing = object.geometry.morphTargets.length > 0 && objectMaterial.morphTargets;
				useSkinning = object instanceof THREE.SkinnedMesh && objectMaterial.skinning;

				if ( object.customDepthMaterial ) {

					material = object.customDepthMaterial;

				} else if ( useSkinning ) {

					material = useMorphing ? _depthMaterialMorphSkin : _depthMaterialSkin;

				} else if ( useMorphing ) {

					material = _depthMaterialMorph;

				} else {

					material = _depthMaterial;

				}

				if ( buffer instanceof THREE.BufferGeometry ) {

					_renderer.renderBufferDirect( camera, scene.__lights, fog, material, buffer, object );

				} else {

					_renderer.renderBuffer( camera, scene.__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._modelViewMatrix.multiplyMatrices( camera.matrixWorldInverse, object.matrixWorld );

				_renderer.renderImmediateObject( camera, scene.__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 );

	};

	// For the moment just ignore objects that have multiple materials with different animation methods
	// Only the first material will be taken into account for deciding which depth material to use

	function getObjectMaterial( object ) {

		return object.material instanceof THREE.MeshFaceMaterial
			? object.material.materials[ 0 ]
			: object.material;

	};

};