Add DDGI reflections to transparent materials

Content/Editor/MaterialTemplates/Features/ForwardShading.hlsl

@@ -112,12 +112,17 @@ void PS_Forward(
 	// Calculate lighting from Global Illumination
 #if USE_GI
 	light += GetGlobalIlluminationLighting(gBuffer);
+    // TODO: when using both indirect and specular lighting from DDGI, merge cascade selection and probes visibility resolving to be done once
 #endif
 
 	// Calculate reflections
 #if USE_REFLECTIONS
-	float4 reflections = SampleReflectionProbe(ViewPos, EnvProbe, EnvironmentProbe, gBuffer.WorldPos, gBuffer.Normal, gBuffer.Roughness);
-	reflections.rgb *= reflections.a;
+    float4 reflectionsProbe = SampleReflectionProbe(ViewPos, EnvProbe, EnvironmentProbe, gBuffer.WorldPos, gBuffer.Normal, gBuffer.Roughness);
+    float3 reflections = reflectionsProbe.rgb * reflectionsProbe.a;
+#if USE_GI
+    float4 reflectionsGI = GetGlobalIlluminationSpecular(gBuffer);
+    reflections = lerp(reflections, reflectionsGI.rgb, reflectionsGI.a);
+#endif
 
 #if MATERIAL_REFLECTIONS == MATERIAL_REFLECTIONS_SSR
 	// Screen Space Reflections
@@ -133,7 +138,7 @@ void PS_Forward(
 	if (hit.z > 0)
 	{
 		float3 screenColor = sceneColorTexture.SampleLevel(SamplerPointClamp, hit.xy, 0).rgb;
-		reflections.rgb = lerp(reflections.rgb, screenColor, hit.z);
+		reflections = lerp(reflections, screenColor, hit.z);
 	}
 
 	// Fallback to software tracing if possible
@@ -145,18 +150,17 @@ void PS_Forward(
 		if (TraceSDFSoftwareReflections(gBuffer, reflectWS, surfaceAtlas))
 		{
 			float3 screenColor = sceneColorTexture.SampleLevel(SamplerPointClamp, hit.xy, 0).rgb;
-        	reflections.rgb = lerp(surfaceAtlas, float4(screenColor, 1), hit.z);
+        	reflections = lerp(surfaceAtlas, float4(screenColor, 1), hit.z);
 		}
 	}
 #endif
 #endif
 
-	light.rgb += reflections.rgb * GetReflectionSpecularLighting(PreIntegratedGF, ViewPos, gBuffer);
+	light.rgb += reflections * GetReflectionSpecularLighting(PreIntegratedGF, ViewPos, gBuffer);
 #endif
 
 	// Add lighting
 	output.rgb += light.rgb;
-
 #endif
 
 #if USE_FOG && MATERIAL_SHADING_MODEL != SHADING_MODEL_UNLIT

Content/Editor/MaterialTemplates/Features/GlobalIllumination.hlsl

@@ -8,16 +8,24 @@
 @2// Global Illumination: Constants
 DDGIData DDGI;
 @3// Global Illumination: Resources
-Texture2D<snorm float4> ProbesState : register(t__SRV__);
+Texture2D<snorm float4> ProbesData : register(t__SRV__);
 Texture2D<float4> ProbesDistance : register(t__SRV__);
 Texture2D<float4> ProbesIrradiance : register(t__SRV__);
+Texture2D<float4> ProbesRadiance : register(t__SRV__);
 @4// Global Illumination: Utilities
 float4 GetGlobalIlluminationLighting(GBufferSample gBuffer)
 {
-	float3 irradiance = SampleDDGIIrradiance(DDGI, ProbesState, ProbesDistance, ProbesIrradiance, gBuffer.WorldPos, gBuffer.Normal);
+    float3 irradiance = SampleDDGIIrradiance(DDGI, ProbesData, ProbesDistance, ProbesIrradiance, gBuffer.WorldPos, gBuffer.Normal);
 	float3 diffuseColor = GetDiffuseColor(gBuffer);
 	float3 diffuse = Diffuse_Lambert(diffuseColor);
 	return float4(diffuse * irradiance, saturate(length(irradiance)));
 }
 
+float4 GetGlobalIlluminationSpecular(GBufferSample gBuffer)
+{
+    float3 specular = SampleDDGISpecular(DDGI, ProbesData, ProbesDistance, ProbesRadiance, gBuffer.WorldPos, gBuffer.Normal, gBuffer.Roughness);
+    float useRadiance = DDGI.BlendOrigin[0].w; // 1 or 0
+    return float4(specular, useRadiance);
+}
+
 @5// Global Illumination: Shaders

Flax.flaxproj

@@ -4,7 +4,7 @@
     "Major": 1,
     "Minor": 13,
     "Revision": 0,
-    "Build": 7007
+    "Build": 7008
   },
   "Company": "Flax",
   "Copyright": "Copyright (c) 2012-2026 Wojciech Figat. All rights reserved.",

Source/Engine/Graphics/Materials/MaterialShader.h

@@ -10,7 +10,7 @@
 /// <summary>
 /// Current materials shader version.
 /// </summary>
-#define MATERIAL_GRAPH_VERSION 184
+#define MATERIAL_GRAPH_VERSION 185
 
 class Material;
 class GPUShader;

Source/Engine/Graphics/Materials/MaterialShaderFeatures.cpp

@@ -172,6 +172,7 @@ bool GlobalIlluminationFeature::Bind(MaterialShader::BindParameters& params, Spa
                 params.GPUContext->BindSR(srv + 0, bindingDataDDGI.ProbesData);
                 params.GPUContext->BindSR(srv + 1, bindingDataDDGI.ProbesDistance);
                 params.GPUContext->BindSR(srv + 2, bindingDataDDGI.ProbesIrradiance);
+                params.GPUContext->BindSR(srv + 3, bindingDataDDGI.ProbesRadiance);
             }
             break;
         }
@@ -185,6 +186,7 @@ bool GlobalIlluminationFeature::Bind(MaterialShader::BindParameters& params, Spa
         params.GPUContext->UnBindSR(srv + 0);
         params.GPUContext->UnBindSR(srv + 1);
         params.GPUContext->UnBindSR(srv + 2);
+        params.GPUContext->UnBindSR(srv + 3);
     }
 
     cb = cb.Slice(sizeof(Data));

Source/Engine/Graphics/Materials/MaterialShaderFeatures.h

@@ -73,7 +73,7 @@ struct LightmapFeature : MaterialShaderFeature
 // Material shader feature that adds Global Illumination sampling feature (light probes).
 struct GlobalIlluminationFeature : MaterialShaderFeature
 {
-    enum { SRVs = 3 };
+    enum { SRVs = 4 };
 
     PACK_STRUCT(struct Data {
         DynamicDiffuseGlobalIlluminationPass::ConstantsData DDGI;

Source/Engine/Renderer/GI/DynamicDiffuseGlobalIllumination.cpp

@@ -648,6 +648,7 @@ bool DynamicDiffuseGlobalIlluminationPass::RenderInner(RenderContext& renderCont
             ddgiData.Result.Constants.BlendOrigin[cascadeIndex] = Float4(blendOrigins[cascadeIndex], 0.0f);
             ddgiData.Result.Constants.ProbesScrollOffsets[cascadeIndex] = Int4(cascade.ProbeScrollOffsets, 0);
         }
+        ddgiData.Result.Constants.BlendOrigin[0].W = ddgiData.ProbesRadiance ? 1.0f : 0.0f; // Use radiance flag
         ddgiData.Result.Constants.RayMaxDistance = distance;
         ddgiData.Result.Constants.ViewPos = renderContext.View.Position;
         ddgiData.Result.Constants.RaysCount = probeRaysCount;

Source/Engine/Renderer/GI/DynamicDiffuseGlobalIllumination.h

@@ -15,7 +15,7 @@ public:
     // Constant buffer data for DDGI access on a GPU.
     GPU_CB_STRUCT(ConstantsData {
         Float4 ProbesOriginAndSpacing[4];
-        Float4 BlendOrigin[4]; // w is unused
+        Float4 BlendOrigin[4]; // [0] w is flag for specular usage, [1-3] w is unused
         Int4 ProbesScrollOffsets[4]; // w is unused
         uint32 ProbesCounts[3];
         uint32 CascadesCount;

Source/Shaders/GI/DDGI.hlsl

@@ -38,7 +38,7 @@
 struct DDGIData
 {
     float4 ProbesOriginAndSpacing[4];
-    float4 BlendOrigin[4]; // w is unused
+    float4 BlendOrigin[4]; // [0] w is flag for specular usage, [1-3] w is unused
     int4 ProbesScrollOffsets[4]; // w is unused
     uint3 ProbesCounts;
     uint CascadesCount;