feat: #86 Add auto exposure

Assets/BuiltIn/Shader/PostProcessing/AdaptLuminance.xml

@@ -0,0 +1,16 @@
+<shaderConfig name="AdaptLuminance" baseShader="SOLID">
+	<uniforms>
+		<vs>
+			<uniform name="uMvpMatrix" type="WORLD_VIEW_PROJECTION" value="0" float="16" matrix="true"/>
+		</vs>
+		<fs>
+			<uniform name="uTexLuminance" type="DEFAULT_VALUE" value="0" float="1" directX="false"/>
+			<uniform name="uTexLastLuminance" type="DEFAULT_VALUE" value="1" float="1" directX="false"/>
+			<uniform name="uTimeStep" type="TIME_STEP" value="0,0" float="2"/>
+		</fs>
+	</uniforms>
+	<customUI>
+	</customUI>
+	<shader type="GLSL" vs="GLSL/PostEffectVS.glsl" fs="GLSL/AdaptLuminanceFS.glsl"/>
+	<shader type="HLSL" vs="HLSL/PostEffectVS.hlsl" fs="HLSL/AdaptLuminanceFS.hlsl"/>
+</shaderConfig>

Assets/BuiltIn/Shader/PostProcessing/GLSL/AdaptLuminanceFS.glsl

@@ -0,0 +1,20 @@
+precision mediump float;
+
+uniform sampler2D uTexLuminance;
+uniform sampler2D uTexLastLuminance;
+
+uniform vec2 uTimeStep;
+
+in vec2 varTexCoord0;
+in vec4 varColor;
+out vec4 FragColor;
+
+void main(void)
+{
+	float lum = texture(uTexLuminance, varTexCoord0).x;
+	float lastLum = texture(uTexLastLuminance, varTexCoord0).x;
+
+	float adaptLum = lastLum + (lum - lastLum) * uTimeStep.x * 0.001;
+
+	FragColor = vec4(adaptLum, 0, 0, 0);	 
+}

Assets/BuiltIn/Shader/PostProcessing/GLSL/PostEffectFS.d.glsl

@@ -15,7 +15,7 @@ void main(void)
 {
 	vec4 color = texture(uTexColor, varTexCoord0.xy);
 
-	float avgLuminance = textureLod(uTexLuminance, varTexCoord0.xy, 10.0).x;			
+	float avgLuminance = textureLod(uTexLuminance, varTexCoord0.xy, 10.0).x;
 
 	float target = 0.2;
 	float threshold = 2.5;

Assets/BuiltIn/Shader/PostProcessing/HLSL/AdaptLuminanceFS.hlsl

@@ -0,0 +1,27 @@
+Texture2D uTexLuminance : register(t0);
+SamplerState uTexLuminanceSampler : register(s0);
+
+Texture2D uTexLastLuminance : register(t1);
+SamplerState uTexLastLuminanceSampler : register(s1);
+
+struct PS_INPUT
+{
+	float4 pos : SV_POSITION;
+	float4 color : COLOR0;
+	float2 tex0 : TEXCOORD0;
+};
+
+cbuffer cbPerFrame
+{
+	float2 uTimeStep;
+}
+
+float4 main(PS_INPUT input) : SV_TARGET
+{
+	float lum = uTexLuminance.Sample(uTexLuminanceSampler, input.tex0).x;
+	float lastLum = uTexLastLuminance.Sample(uTexLastLuminanceSampler, input.tex0).x;
+
+	float adaptLum = lastLum + (lum - lastLum) * uTimeStep.x * 0.001;
+
+	return float4(adaptLum, 0, 0, 0);
+}

Assets/BuiltIn/Shader/PostProcessing/HLSL/PostEffectFS.d.hlsl

@@ -17,7 +17,7 @@ float4 main(PS_INPUT input) : SV_TARGET
 {
 	float4 color = uTexColor.Sample(uTexColorSampler, input.tex0);
 
-	float avgLuminance = uTexLuminance.SampleLevel(uTexLuminanceSampler, input.tex0, 10.0).x;
+	float avgLuminance = uTexLuminance.SampleLevel(uTexLuminanceSampler, input.tex0, 10.0).x;	
 
 	float target = 0.2;
 	float threshold = 2.5;

Projects/Skylicht/Engine/Source/Material/Shader/CShader.cpp

@@ -123,6 +123,7 @@ namespace Skylicht
 			"SSAO_KERNEL",
 			"DEFERRED_VIEW",
 			"DEFERRED_PROJECTION",
+			"TIME_STEP",
 			"NULL"
 		};
 
@@ -914,6 +915,17 @@ namespace Skylicht
 			}
 		}
 		break;
+		case TIME_STEP:
+		{
+			float timestep[2] = { 0 };
+			timestep[0] = getTimeStep();
+
+			if (vertexShader == true)
+				matRender->setShaderVariable(uniform.UniformShaderID, timestep, uniform.SizeOfUniform, video::EST_VERTEX_SHADER);
+			else
+				matRender->setShaderVariable(uniform.UniformShaderID, timestep, uniform.SizeOfUniform, video::EST_PIXEL_SHADER);
+		}
+		break;
 		case DEFAULT_VALUE:
 		case CONFIG_VALUE:
 		{

Projects/Skylicht/Engine/Source/Material/Shader/CShader.h

@@ -70,6 +70,7 @@ namespace Skylicht
 		SSAO_KERNEL,
 		DEFERRED_VIEW,
 		DEFERRED_PROJECTION,
+		TIME_STEP,
 		NUM_SHADER_TYPE,
 	};
 

Projects/Skylicht/Engine/Source/Material/Shader/CShaderManager.cpp

@@ -95,6 +95,7 @@ namespace Skylicht
 		loadShader("BuiltIn/Shader/Lightmap/IndirectTest.xml");
 		loadShader("BuiltIn/Shader/Lightmap/LightmapVertex.xml");
 
+		loadShader("BuiltIn/Shader/PostProcessing/AdaptLuminance.xml");
 		loadShader("BuiltIn/Shader/PostProcessing/PostEffect.xml");
 	}
 
@@ -110,7 +111,7 @@ namespace Skylicht
 		loadShader("BuiltIn/Shader/SpecularGlossiness/Lighting/SGDirectionalLightBake.xml");
 		loadShader("BuiltIn/Shader/SpecularGlossiness/Lighting/SGPointLight.xml");
 		loadShader("BuiltIn/Shader/SpecularGlossiness/Lighting/SGPointLightShadow.xml");
-		loadShader("BuiltIn/Shader/SpecularGlossiness/Forward/SH.xml");		
+		loadShader("BuiltIn/Shader/SpecularGlossiness/Forward/SH.xml");
 	}
 
 	void CShaderManager::initSkylichtEngineShader()

Projects/Skylicht/Engine/Source/RenderPipeline/CPostProcessorRP.cpp

@@ -29,17 +29,19 @@ This file is part of the "Skylicht Engine".
 namespace Skylicht
 {
 	CPostProcessorRP::CPostProcessorRP() :
-		m_currentLum(NULL),
-		m_lastLum(NULL)
+		m_adaptLum(NULL),
+		m_lumTarget(0)
 	{
-
+		m_luminance[0] = NULL;
+		m_luminance[1] = NULL;
 	}
 
 	CPostProcessorRP::~CPostProcessorRP()
 	{
 		IVideoDriver *driver = getVideoDriver();
 		driver->removeTexture(m_luminance[0]);
 		driver->removeTexture(m_luminance[1]);
+		driver->removeTexture(m_adaptLum);
 	}
 
 	void CPostProcessorRP::initRender(int w, int h)
@@ -53,12 +55,14 @@ namespace Skylicht
 
 		m_luminance[0] = driver->addRenderTargetTexture(m_lumSize, "lum_0", ECF_R16F);
 		m_luminance[1] = driver->addRenderTargetTexture(m_lumSize, "lum_1", ECF_R16F);
+		m_adaptLum = driver->addRenderTargetTexture(m_lumSize, "lum_adapt", ECF_R16F);
 
 		// init final pass shader
 		m_finalPass.MaterialType = shaderMgr->getShaderIDByName("PostEffect");
 
 		// init lum pass shader
 		m_lumPass.MaterialType = shaderMgr->getShaderIDByName("Luminance");
+		m_adaptLumPass.MaterialType = shaderMgr->getShaderIDByName("AdaptLuminance");
 	}
 
 	void CPostProcessorRP::render(ITexture *target, CCamera *camera, CEntityManager *entityManager, const core::recti& viewport)
@@ -71,27 +75,26 @@ namespace Skylicht
 
 	void CPostProcessorRP::luminanceMapGeneration(ITexture *color)
 	{
-		if (m_lastLum == m_luminance[0])
-		{
-			m_currentLum = m_luminance[1];
-			m_lastLum = m_luminance[0];
-		}
-		else
-		{
-			m_currentLum = m_luminance[0];
-			m_lastLum = m_luminance[1];
-		}
+		float w = (float)m_lumSize.Width;
+		float h = (float)m_lumSize.Height;
 
+		// Step 1: Generate target luminance from color to lum[0]
 		IVideoDriver * driver = getVideoDriver();
-		driver->setRenderTarget(m_currentLum, true, true);
+		driver->setRenderTarget(m_adaptLum, true, true);
 
 		m_lumPass.setTexture(0, color);
 
-		float w = (float)m_lumSize.Width;
-		float h = (float)m_lumSize.Height;
-
 		beginRender2D(w, h);
 		renderBufferToTarget(0.0f, 0.0f, w, h, m_lumPass);
+
+		// Step 2: Interpolate to target luminance
+		driver->setRenderTarget(m_luminance[m_lumTarget], true, true);
+
+		m_adaptLumPass.setTexture(0, m_adaptLum);
+		m_adaptLumPass.setTexture(1, m_luminance[!m_lumTarget]);
+
+		beginRender2D(w, h);
+		renderBufferToTarget(0.0f, 0.0f, w, h, m_adaptLumPass);
 	}
 
 	void CPostProcessorRP::postProcessing(ITexture *finalTarget, ITexture *color, ITexture *normal, ITexture *position, const core::recti& viewport)
@@ -100,8 +103,6 @@ namespace Skylicht
 
 		luminanceMapGeneration(color);
 
-		m_currentLum->regenerateMipMapLevels();
-
 		driver->setRenderTarget(finalTarget, false, false);
 
 		float renderW = (float)m_size.Width;
@@ -114,13 +115,14 @@ namespace Skylicht
 			renderH = (float)viewport.getHeight();
 		}
 
-		m_finalPass.setTexture(0, color);		
-		m_finalPass.setTexture(1, m_currentLum);
-		m_finalPass.setTexture(2, m_lastLum);
+		m_luminance[m_lumTarget]->regenerateMipMapLevels();
+
+		m_finalPass.setTexture(0, color);
+		m_finalPass.setTexture(1, m_luminance[m_lumTarget]);
 
 		beginRender2D(renderW, renderH);
 		renderBufferToTarget(0.0f, 0.0f, renderW, renderH, m_finalPass);
 
-		m_lastLum = m_currentLum;
+		m_lumTarget = !m_lumTarget;
 	}
 }

Projects/Skylicht/Engine/Source/RenderPipeline/CPostProcessorRP.h

@@ -35,11 +35,12 @@ namespace Skylicht
 		core::dimension2du m_lumSize;
 
 		ITexture *m_luminance[2];
-		ITexture *m_lastLum;
-		ITexture *m_currentLum;
+		ITexture *m_adaptLum;
+		int m_lumTarget;
 
 		SMaterial m_finalPass;
 		SMaterial m_lumPass;
+		SMaterial m_adaptLumPass;
 
 	public:
 		CPostProcessorRP();