Implement shadows rendering to direct light atlas (with Glboal SDF tracing)

Source/Engine/Renderer/GlobalSurfaceAtlasPass.cpp

@@ -32,7 +32,8 @@ PACK_STRUCT(struct Data0
     {
     Vector3 ViewWorldPos;
     float ViewNearPlane;
-    Vector3 Padding00;
+    Vector2 Padding00;
+    float LightShadowsStrength;
     float ViewFarPlane;
     Vector4 ViewFrustumWorldRays[4];
     GlobalSignDistanceFieldPass::GlobalSDFData GlobalSDF;
@@ -51,7 +52,7 @@ PACK_STRUCT(struct AtlasTileVertex
 struct GlobalSurfaceAtlasTile : RectPack<GlobalSurfaceAtlasTile, uint16>
 {
     Vector3 ViewDirection;
-    Vector3 ViewPosition; // TODO: use from ViewMatrix
+    Vector3 ViewPosition;
     Vector3 ViewBoundsSize;
     Matrix ViewMatrix;
 
@@ -428,7 +429,6 @@ bool GlobalSurfaceAtlasPass::Render(RenderContext& renderContext, GPUContext* co
 
                             // Insert tile into atlas
                             auto* tile = surfaceAtlasData.AtlasTiles->Insert(tileResolution, tileResolution, 0, &surfaceAtlasData, e.Actor, tileIndex);
-                            // TODO: try to perform atlas defragmentation if it's full (eg. max once per ~10s)
                             if (tile)
                             {
                                 if (!object)
@@ -680,7 +680,10 @@ bool GlobalSurfaceAtlasPass::Render(RenderContext& renderContext, GPUContext* co
 
         // Copy emissive light into the final direct lighting atlas
         // TODO: test perf diff when manually copying only dirty object tiles and dirty light tiles
-        context->CopyTexture(surfaceAtlasData.AtlasDirectLight, 0, 0, 0, 0, surfaceAtlasData.AtlasEmissive, 0);
+        {
+            PROFILE_GPU_CPU("Copy Emissive");
+            context->CopyTexture(surfaceAtlasData.AtlasDirectLight, 0, 0, 0, 0, surfaceAtlasData.AtlasEmissive, 0);
+        }
 
         context->SetViewportAndScissors(Viewport(0, 0, resolution, resolution));
         context->SetRenderTarget(surfaceAtlasData.AtlasDirectLight->View());
@@ -689,6 +692,11 @@ bool GlobalSurfaceAtlasPass::Render(RenderContext& renderContext, GPUContext* co
         context->BindSR(2, surfaceAtlasData.AtlasGBuffer2->View());
         context->BindSR(3, surfaceAtlasData.AtlasDepth->View());
         context->BindSR(4, surfaceAtlasData.ObjectsBuffer.GetBuffer()->View());
+        for (int32 i = 0; i < 4; i++)
+        {
+            context->BindSR(i + 5, bindingDataSDF.Cascades[i]->ViewVolume());
+            context->BindSR(i + 9, bindingDataSDF.CascadeMips[i]->ViewVolume());
+        }
         context->BindCB(0, _cb0);
         Data0 data;
         data.ViewWorldPos = renderContext.View.Position;
@@ -717,6 +725,7 @@ bool GlobalSurfaceAtlasPass::Render(RenderContext& renderContext, GPUContext* co
             const bool useShadow = CanRenderShadow(renderContext.View, light);
             // TODO: test perf/quality when using Shadow Map for directional light (ShadowsPass::Instance()->LastDirLightShadowMap) instead of Global SDF trace
             light.SetupLightData(&data.Light, useShadow);
+            data.LightShadowsStrength = 1.0f - light.ShadowsStrength;
             context->UpdateCB(_cb0, &data);
             context->SetState(_psDirectLighting0);
             VB_DRAW();
@@ -743,6 +752,7 @@ bool GlobalSurfaceAtlasPass::Render(RenderContext& renderContext, GPUContext* co
             // Draw draw light
             const bool useShadow = CanRenderShadow(renderContext.View, light);
             light.SetupLightData(&data.Light, useShadow);
+            data.LightShadowsStrength = 1.0f - light.ShadowsStrength;
             context->UpdateCB(_cb0, &data);
             context->SetState(_psDirectLighting1);
             VB_DRAW();
@@ -769,6 +779,7 @@ bool GlobalSurfaceAtlasPass::Render(RenderContext& renderContext, GPUContext* co
             // Draw draw light
             const bool useShadow = CanRenderShadow(renderContext.View, light);
             light.SetupLightData(&data.Light, useShadow);
+            data.LightShadowsStrength = 1.0f - light.ShadowsStrength;
             context->UpdateCB(_cb0, &data);
             context->SetState(_psDirectLighting1);
             VB_DRAW();
@@ -779,6 +790,8 @@ bool GlobalSurfaceAtlasPass::Render(RenderContext& renderContext, GPUContext* co
 
     // TODO: indirect lighting apply to get infinite bounces for GI
 
+    // TODO: explore atlas tiles optimization with feedback from renderer (eg. when tile is sampled by GI/Reflections mark it as used, then sort tiles by importance and prioritize updates for ones frequently used)
+
 #undef WRITE_TILE
     return false;
 }

Source/Shaders/GlobalSignDistanceField.hlsl

@@ -6,6 +6,7 @@
 #define GLOBAL_SDF_RASTERIZE_CHUNK_SIZE 32
 #define GLOBAL_SDF_RASTERIZE_CHUNK_MARGIN 4
 #define GLOBAL_SDF_MIP_FLOODS 5
+#define GLOBAL_SDF_WORLD_SIZE 60000.0f
 
 // Global SDF data for a constant buffer
 struct GlobalSDFData
@@ -61,7 +62,7 @@ float SampleGlobalSDF(const GlobalSDFData data, Texture3D<float> tex[4], float3
 {
 	float distance = data.CascadePosDistance[3].w * 2.0f;
 	if (distance <= 0.0f)
-		return 60000;
+		return GLOBAL_SDF_WORLD_SIZE;
 	UNROLL
 	for (uint cascade = 0; cascade < 4; cascade++)
 	{
@@ -83,7 +84,7 @@ float SampleGlobalSDF(const GlobalSDFData data, Texture3D<float> tex[4], float3
 float3 SampleGlobalSDFGradient(const GlobalSDFData data, Texture3D<float> tex[4], float3 worldPosition, out float distance)
 {
 	float3 gradient = float3(0, 0.00001f, 0);
-	distance = 60000;
+	distance = GLOBAL_SDF_WORLD_SIZE;
 	if (data.CascadePosDistance[3].w <= 0.0f)
 		return gradient;
 	UNROLL

Source/Shaders/GlobalSurfaceAtlas.shader

@@ -12,7 +12,8 @@
 META_CB_BEGIN(0, Data)
 float3 ViewWorldPos;
 float ViewNearPlane;
-float3 Padding00;
+float2 Padding00;
+float LightShadowsStrengthOneMinus;
 float ViewFarPlane;
 float4 ViewFrustumWorldRays[4];
 GlobalSDFData GlobalSDF;
@@ -66,6 +67,8 @@ void PS_Clear(out float4 Light : SV_Target0, out float4 RT0 : SV_Target1, out fl
 
 // GBuffer+Depth at 0-3 slots
 Buffer<float4> GlobalSurfaceAtlasObjects : register(t4);
+Texture3D<float> GlobalSDFTex[4] : register(t5);
+Texture3D<float> GlobalSDFMip[4] : register(t9);
 
 // Pixel shader for Global Surface Atlas shading with direct light contribution
 META_PS(true, FEATURE_LEVEL_SM5)
@@ -81,11 +84,10 @@ float4 PS_DirectLighting(AtlasVertexOutput input) : SV_Target
 	// Load GBuffer sample from atlas
 	GBufferData gBufferData = (GBufferData)0;
 	GBufferSample gBuffer = SampleGBuffer(gBufferData, atlasUV);
-
-	// Skip unlit pixels
 	BRANCH
 	if (gBuffer.ShadingModel == SHADING_MODEL_UNLIT)
 	{
+		// Skip unlit pixels
 		discard;
 		return 0;
 	}
@@ -102,11 +104,43 @@ float4 PS_DirectLighting(AtlasVertexOutput input) : SV_Target
 	float4x4 tileLocalToWorld = Inverse(tile.WorldToLocal);
 	gBuffer.WorldPos = mul(float4(gBufferTilePos, 1), tileLocalToWorld).xyz;
 
+	// Calculate shadowing
+	float3 L = Light.Direction;
+#if RADIAL_LIGHT
+	float3 toLight = Light.Position - gBuffer.WorldPos;
+	float toLightDst = length(toLight);
+	if (toLightDst >= Light.Radius)
+	{
+		// Skip texels outside the light influence range
+		discard;
+		return 0;
+	}
+	L = toLight / toLightDst;
+#else
+	float toLightDst = GLOBAL_SDF_WORLD_SIZE;
+#endif
 	float4 shadowMask = 1;
-	BRANCH
 	if (Light.CastShadows > 0)
 	{
-		// TODO: calculate shadow for the light (use Global SDF)
+		float NoL = dot(gBuffer.Normal, L);
+		float shadowBias = 10.0f;
+		float bias = 2 * shadowBias * saturate(1 - NoL) + shadowBias;
+		BRANCH
+		if (NoL > 0)
+		{
+			// TODO: try using shadow map for on-screen pixels
+			// TODO: try using cone trace with Global SDF for smoother shadow (eg. for sun shadows or for area lights)
+
+			// Shot a ray from light into texel to see if there is any occluder
+			GlobalSDFTrace trace;
+			trace.Init(gBuffer.WorldPos + gBuffer.Normal * shadowBias, L, bias, toLightDst - bias);
+			GlobalSDFHit hit = RayTraceGlobalSDF(GlobalSDF, GlobalSDFTex, GlobalSDFMip, trace);
+			shadowMask = hit.IsHit() ? LightShadowsStrengthOneMinus : 1;
+		}
+		else
+		{
+			shadowMask = 0;
+		}
 	}
 
 	// Calculate lighting