/src/aerys/minko/render/effect/lightScattering/LightScatteringPostProcessShader.as

  1package aerys.minko.render.effect.lightScattering
  2{
  3	import aerys.minko.render.resource.texture.TextureResource;
  4	import aerys.minko.render.shader.SFloat;
  5	import aerys.minko.render.shader.Shader;
  6	import aerys.minko.render.shader.ShaderSettings;
  7	import aerys.minko.render.shader.part.PostProcessingShaderPart;
  8	import aerys.minko.scene.data.lightScattering.LightScatteringProvider;
  9	import aerys.minko.type.enum.Blending;
 10	import aerys.minko.type.enum.DepthTest;
 11	import aerys.minko.type.enum.SamplerFiltering;
 12	import aerys.minko.type.enum.SamplerMipMapping;
 13	import aerys.minko.type.enum.SamplerWrapping;
 14	import aerys.minko.type.enum.TriangleCulling;
 15	import aerys.minko.type.math.Vector4;
 16	
 17	import flash.utils.Dictionary;
 18	
 19	public class LightScatteringPostProcessShader extends Shader
 20	{
 21		private var _postProcessing	: PostProcessingShaderPart	= null;
 22		
 23		private var _numSamples		: Number					= 0.;
 24		private var _nbPasses		: Number					= 0.;
 25		private var _curPass		: Number					= 0.;
 26		private var _occludedSource	: TextureResource			= null;
 27		
 28		public function LightScatteringPostProcessShader(numSamples		: Number,
 29									   				   	 nbPasses		: Number,
 30									   				     curPass		: Number,
 31									   				   	 occlusionMap	: TextureResource)
 32		{
 33			_nbPasses = nbPasses;
 34			_curPass = curPass;
 35			_numSamples = numSamples;
 36			_occludedSource = occlusionMap;
 37			
 38			_postProcessing = new PostProcessingShaderPart(this);
 39		}
 40		
 41		override protected function initializeSettings(settings:ShaderSettings):void
 42		{
 43			super.initializeSettings(settings);
 44			
 45			settings.depthTest			= DepthTest.ALWAYS;
 46			settings.blending			= Blending.ADDITIVE;
 47			settings.triangleCulling	= TriangleCulling.NONE;
 48		}
 49		
 50		override protected function getVertexPosition() : SFloat
 51		{
 52			return _postProcessing.vertexPosition;
 53		}
 54		
 55		private function localToUV(value : SFloat) : SFloat
 56		{
 57			return divide(add(localToScreen(value), 1), 2);
 58		}
 59		
 60		override protected function getPixelColor() : SFloat
 61		{
 62			var lightPosition		: SFloat	= sceneBindings.getParameter(LightScatteringProperties.SOURCE_POSITION, 4);
 63			var lighDirection 		: SFloat 	= normalize(subtract(lightPosition, cameraPosition));
 64			var textureVertexPos	: SFloat	= saturate(interpolate(vertexUV));
 65			var textureLightPos		: SFloat	= localToUV(lightPosition);		
 66			var vertexToLightDelta	: SFloat	= subtract(divide(textureLightPos.xy, textureLightPos.w), textureVertexPos);
 67			
 68			var cameraDirection		: SFloat	= normalize(this.cameraDirection);
 69			var dotProductResult	: SFloat	= dotProduct3(lighDirection, normalize(cameraDirection));
 70			var colorMultiplier 	: SFloat 	= subtract(dotProductResult, 0.5);
 71			
 72			var occlusionMap		: SFloat	= getTexture(
 73				_occludedSource,
 74				SamplerFiltering.LINEAR,
 75				SamplerMipMapping.LINEAR,
 76				SamplerWrapping.CLAMP
 77			);
 78			var initialColor		: SFloat	= sampleTexture(occlusionMap, textureVertexPos);
 79			var illumDecay			: SFloat	= float(1.);
 80			var sampleColor 		: SFloat	= null;
 81			
 82			// light scattering source values
 83			var sourceCensity		: SFloat	= sceneBindings.getParameter(LightScatteringProperties.SOURCE_DENSITY, 1);
 84			var sourceWeight		: SFloat	= sceneBindings.getParameter(LightScatteringProperties.SOURCE_WEIGHT, 1);
 85			var sourceDecay			: SFloat	= sceneBindings.getParameter(LightScatteringProperties.SOURCE_DECAY, 1);
 86			var sourceExposure		: SFloat	= sceneBindings.getParameter(LightScatteringProperties.SOURCE_EXPOSURE, 1);
 87			
 88			vertexToLightDelta = multiply(vertexToLightDelta, divide(sourceCensity, _numSamples));
 89			textureVertexPos = add(textureVertexPos, multiply(divide(vertexToLightDelta, _nbPasses), _curPass));
 90
 91			for (var i : int = 0; i < _numSamples; ++i)
 92			{
 93				textureVertexPos = add(textureVertexPos, vertexToLightDelta);
 94				sampleColor		 = sampleTexture(occlusionMap, textureVertexPos);
 95				sampleColor		 = multiply(sampleColor, sourceWeight, illumDecay);
 96				initialColor	 = add(initialColor, sampleColor);
 97
 98				illumDecay.scaleBy(sourceDecay);
 99			}
100			
101			return float4(
102				multiply(initialColor.rgb, sourceExposure, colorMultiplier),
103				1.
104			);
105		}
106	}
107}