Graphics: Add gamma correction

src/Nazara/Graphics/ForwardFramePipeline.cpp

@@ -257,6 +257,9 @@ namespace Nz
 		if (passFlags.Test(FramePipelineExtraPass::DepthPrepass))
 			viewerData.depthPrepass = std::make_unique<DepthPipelinePass>(*this, m_elementRegistry, viewerInstance, depthPassIndex, "Depth pre-pass");
 
+		if (passFlags.Test(FramePipelineExtraPass::GammaCorrection))
+			viewerData.gammaCorrectionPass = std::make_unique<PostProcessPipelinePass>(*this, "Gamma correction", "PostProcess.GammaCorrection");
+
 		m_transferSet.insert(&viewerInstance->GetViewerInstance());
 
 		m_rebuildFrameGraph = true;
@@ -396,6 +399,9 @@ namespace Nz
 			if (viewerData.depthPrepass)
 				viewerData.depthPrepass->Prepare(renderFrame, frustum, visibleRenderables, depthVisibilityHash);
 
+			if (viewerData.gammaCorrectionPass)
+				viewerData.gammaCorrectionPass->Prepare(renderFrame);
+
 			viewerData.forwardPass->Prepare(renderFrame, frustum, visibleRenderables, m_visibleLights, visibilityHash);
 
 			if (viewerData.debugDrawPass)
@@ -611,7 +617,6 @@ namespace Nz
 				PixelFormat::RGBA8
 			});
 			
-
 			viewerData.depthStencilAttachment = frameGraph.AddAttachment({
 				"Depth-stencil buffer",
 				Graphics::Instance()->GetPreferredDepthStencilFormat()
@@ -627,14 +632,25 @@ namespace Nz
 				lightData->shadowData->RegisterPassInputs(forwardPass);
 			}
 
+			viewerData.finalColorAttachment = viewerData.forwardColorAttachment;
+
+			if (viewerData.gammaCorrectionPass)
+			{
+				std::size_t postGammaColorAttachment = frameGraph.AddAttachment({
+					"Gamma-corrected output",
+					PixelFormat::RGBA8
+				});
+
+				viewerData.gammaCorrectionPass->RegisterToFrameGraph(frameGraph, viewerData.finalColorAttachment, postGammaColorAttachment);
+				viewerData.finalColorAttachment = postGammaColorAttachment;
+			}
+
 			if (viewerData.debugDrawPass)
 			{
-				viewerData.debugColorAttachment = frameGraph.AddAttachmentProxy("Debug draw output", viewerData.forwardColorAttachment);
-				viewerData.debugDrawPass->RegisterToFrameGraph(frameGraph, viewerData.forwardColorAttachment, viewerData.debugColorAttachment);
+				viewerData.debugColorAttachment = frameGraph.AddAttachmentProxy("Debug draw output", viewerData.finalColorAttachment);
+				viewerData.debugDrawPass->RegisterToFrameGraph(frameGraph, viewerData.finalColorAttachment, viewerData.debugColorAttachment);
 				viewerData.finalColorAttachment = viewerData.debugColorAttachment;
 			}
-			else
-				viewerData.finalColorAttachment = viewerData.forwardColorAttachment;
 		}
 
 		using ViewerPair = std::pair<const RenderTarget*, const ViewerData*>;

src/Nazara/Graphics/PostProcessPipelinePass.cpp

@@ -0,0 +1,107 @@
+// Copyright (C) 2023 Jérôme "Lynix" Leclercq (lynix680@gmail.com)
+// This file is part of the "Nazara Engine - Graphics module"
+// For conditions of distribution and use, see copyright notice in Config.hpp
+
+#include <Nazara/Graphics/PostProcessPipelinePass.hpp>
+#include <Nazara/Graphics/AbstractViewer.hpp>
+#include <Nazara/Graphics/FrameGraph.hpp>
+#include <Nazara/Graphics/Graphics.hpp>
+#include <Nazara/Renderer/RenderFrame.hpp>
+#include <Nazara/Graphics/Debug.hpp>
+
+namespace Nz
+{
+	PostProcessPipelinePass::PostProcessPipelinePass(FramePipeline& owner, std::string passName, std::string shaderName) :
+	m_passName(std::move(passName)),
+	m_shader(nzsl::ShaderStageType::Fragment | nzsl::ShaderStageType::Vertex, std::move(shaderName)),
+	m_pipeline(owner)
+	{
+		RenderPipelineLayoutInfo layoutInfo;
+		layoutInfo.bindings.assign({
+			{
+				0, 0, 1,
+				ShaderBindingType::Sampler,
+				nzsl::ShaderStageType::Fragment
+			}
+		});
+
+		std::shared_ptr<RenderDevice> renderDevice = Graphics::Instance()->GetRenderDevice();
+		m_renderPipelineLayout = renderDevice->InstantiateRenderPipelineLayout(std::move(layoutInfo));
+		if (!m_renderPipelineLayout)
+			throw std::runtime_error("failed to instantiate postprocess RenderPipelineLayout");
+
+		m_onShaderUpdated.Connect(m_shader.OnShaderUpdated, [this](UberShader*)
+		{
+			BuildPipeline();
+		});
+		BuildPipeline();
+	}
+
+	void PostProcessPipelinePass::Prepare(RenderFrame& renderFrame)
+	{
+		if (m_nextRenderPipeline)
+		{
+			if (m_renderPipeline)
+				renderFrame.PushForRelease(std::move(m_renderPipeline));
+
+			m_renderPipeline = std::move(m_nextRenderPipeline);
+			m_rebuildFramePass = true;
+		}
+	}
+
+	FramePass& PostProcessPipelinePass::RegisterToFrameGraph(FrameGraph& frameGraph, std::size_t inputColorBufferIndex, std::size_t outputColorBufferIndex)
+	{
+		FramePass& postProcess = frameGraph.AddPass(m_passName);
+		postProcess.AddInput(inputColorBufferIndex);
+		postProcess.AddOutput(outputColorBufferIndex);
+
+		postProcess.SetExecutionCallback([&]()
+		{
+			return (m_rebuildFramePass) ? FramePassExecution::UpdateAndExecute : FramePassExecution::Execute;
+		});
+
+		postProcess.SetCommandCallback([this, inputColorBufferIndex](CommandBufferBuilder& builder, const FramePassEnvironment& env)
+		{
+			if (m_shaderBinding)
+				env.renderFrame.PushForRelease(std::move(m_shaderBinding));
+
+			auto& samplerCache = Graphics::Instance()->GetSamplerCache();
+
+			const auto& sourceTexture = env.frameGraph.GetAttachmentTexture(inputColorBufferIndex);
+			const auto& sampler = samplerCache.Get({});
+
+			m_shaderBinding = m_renderPipelineLayout->AllocateShaderBinding(0);
+			m_shaderBinding->Update({
+				{
+					0,
+					Nz::ShaderBinding::SampledTextureBinding {
+						sourceTexture.get(), sampler.get()
+					}
+				}
+			});
+
+			builder.SetScissor(env.renderRect);
+			builder.SetViewport(env.renderRect);
+
+			builder.BindRenderPipeline(*m_renderPipeline);
+			builder.BindRenderShaderBinding(0, *m_shaderBinding);
+
+			builder.Draw(3);
+
+			m_rebuildFramePass = false;
+		});
+
+		return postProcess;
+	}
+
+	void PostProcessPipelinePass::BuildPipeline()
+	{
+		std::shared_ptr<RenderDevice> renderDevice = Graphics::Instance()->GetRenderDevice();
+
+		RenderPipelineInfo pipelineInfo;
+		pipelineInfo.pipelineLayout = m_renderPipelineLayout;
+		pipelineInfo.shaderModules.push_back(m_shader.Get({}));
+
+		m_nextRenderPipeline = renderDevice->InstantiateRenderPipeline(pipelineInfo);
+	}
+}

src/Nazara/Graphics/Resources/Shaders/Modules/Math/Color.nzsl

@@ -0,0 +1,36 @@
+[nzsl_version("1.0")]
+module Math.Color;
+
+// from https://en.wikipedia.org/wiki/SRGB
+
+option ApproximatesRGB: bool = false;
+
+[export]
+fn LinearTosRGB(color: vec3[f32]) -> vec3[f32]
+{
+	const if (!ApproximatesRGB)
+	{
+		return select(
+			color > (0.0031308).rrr,
+			1.055 * pow(color, (1.0 / 2.4).rrr) - (0.055).rrr,
+			12.92 * color
+		);
+	}
+	else
+		return pow(color, (1.0 / 2.2).rrr);
+}
+
+[export]
+fn sRGBToLinear(color: vec3[f32]) -> vec3[f32]
+{
+	const if (!ApproximatesRGB)
+	{
+		return select(
+			color > (0.04045).rrr,
+			pow((color + (0.055).rrr) / 1.055, (2.4).rrr),
+			color / 12.92
+		);
+	}
+	else
+		return pow(color, (2.2).rrr);
+}

src/Nazara/Graphics/Resources/Shaders/Passes/GammaCorrection.nzsl

@@ -0,0 +1,26 @@
+[nzsl_version("1.0")]
+module PostProcess.GammaCorrection;
+
+import VertOut, VertexShader from Engine.FullscreenVertex;
+import LinearTosRGB from Math.Color;
+
+external
+{
+	[binding(0)] colorTexture: sampler2D[f32]
+}
+
+struct FragOut
+{
+	[location(0)] color: vec4[f32]
+}
+
+[entry(frag)]
+fn main(input: VertOut) -> FragOut
+{
+    let color = colorTexture.Sample(input.uv);
+    color.rgb = LinearTosRGB(color.rgb);
+
+	let output: FragOut;
+	output.color = color;
+	return output;
+}

src/Nazara/Widgets/DefaultWidgetTheme.cpp

@@ -122,7 +122,7 @@ namespace Nz
 	{
 		TextureParams texParams;
 		texParams.renderDevice = Graphics::Instance()->GetRenderDevice();
-		texParams.loadFormat = PixelFormat::RGBA8; //< TODO: Re-enable gamma correction
+		texParams.loadFormat = PixelFormat::RGBA8_SRGB;
 
 		auto CreateMaterialFromTexture = [&](std::shared_ptr<Texture> texture)
 		{