Add IndirectShadowsStrength to GI settings for artist-controlled light leaking

Source/Engine/Graphics/PostProcessSettings.cpp

@@ -33,6 +33,7 @@ void GlobalIlluminationSettings::BlendWith(GlobalIlluminationSettings& other, fl
     BLEND_FLOAT(BounceIntensity);
     BLEND_FLOAT(TemporalResponse);
     BLEND_FLOAT(Distance);
+    BLEND_FLOAT(IndirectShadowsStrength);
     BLEND_COL(FallbackIrradiance);
 }
 

Source/Engine/Graphics/PostProcessSettings.h

@@ -334,10 +334,15 @@ API_ENUM(Attributes="Flags") enum class GlobalIlluminationSettingsOverride : int
     /// </summary>
     BounceIntensity = 1 << 5,
 
+    /// <summary>
+    /// Overrides <see cref="GlobalIlluminationSettings.IndirectShadowsStrength"/> property.
+    /// </summary>
+    IndirectShadowsStrength = 1 << 6,
+
     /// <summary>
     /// All properties.
     /// </summary>
-    All = Mode | Intensity | TemporalResponse | Distance | FallbackIrradiance | BounceIntensity,
+    All = Mode | Intensity | TemporalResponse | Distance | FallbackIrradiance | BounceIntensity | IndirectShadowsStrength,
 };
 
 /// <summary>
@@ -385,6 +390,12 @@ API_STRUCT() struct FLAXENGINE_API GlobalIlluminationSettings : ISerializable
     API_FIELD(Attributes="EditorOrder(30), Limit(1000), PostProcessSetting((int)GlobalIlluminationSettingsOverride.Distance), ValueCategory(Utils.ValueCategory.Distance)")
     float Distance = 20000.0f;
 
+    /// <summary>
+    /// Indirect lighting shadows intensity. Default is 1 for fully opaque shadowing, lower values bleed the lighting into shadowed areas. Can be sued for artistic control over GI.
+    /// </summary>
+    API_FIELD(Attributes = "EditorOrder(35), Limit(0.0f, 1.0f, 0.001f), PostProcessSetting((int)GlobalIlluminationSettingsOverride.IndirectShadowsStrength)")
+    float IndirectShadowsStrength = 1.0f;
+
     /// <summary>
     /// The irradiance lighting outside the GI range used as a fallback to prevent pure-black scene outside the Global Illumination range.
     /// </summary>

Source/Engine/Renderer/GI/DynamicDiffuseGlobalIllumination.cpp

@@ -546,6 +546,7 @@ bool DynamicDiffuseGlobalIlluminationPass::RenderInner(RenderContext& renderCont
         ddgiData.Result.Constants.RaysCount = probeRaysCount;
         ddgiData.Result.Constants.ProbeHistoryWeight = probeHistoryWeight;
         ddgiData.Result.Constants.IndirectLightingIntensity = indirectLightingIntensity;
+        ddgiData.Result.Constants.IndirectShadowsStrength = settings.IndirectShadowsStrength;
         ddgiData.Result.Constants.FallbackIrradiance = settings.FallbackIrradiance.ToFloat4();
         ddgiData.Result.ProbesData = ddgiData.ProbesData->View();
         ddgiData.Result.ProbesDistance = ddgiData.ProbesDistance->View();

Source/Engine/Renderer/GI/DynamicDiffuseGlobalIllumination.h

@@ -19,10 +19,10 @@ public:
         Int4 ProbesScrollOffsets[4]; // w is unused
         uint32 ProbesCounts[3];
         uint32 CascadesCount;
-        float Padding;
         float ProbeHistoryWeight;
         float RayMaxDistance;
         float IndirectLightingIntensity;
+        float IndirectShadowsStrength;
         Float3 ViewPos;
         uint32 RaysCount;
         Float4 FallbackIrradiance;

Source/Shaders/GI/DDGI.hlsl

@@ -41,10 +41,10 @@ struct DDGIData
     int4 ProbesScrollOffsets[4]; // w is unused
     uint3 ProbesCounts;
     uint CascadesCount;
-    float Padding;
     float ProbeHistoryWeight;
     float RayMaxDistance;
     float IndirectLightingIntensity;
+    float IndirectShadowsStrength;
     float3 ViewPos;
     uint RaysCount;
     float4 FallbackIrradiance;
@@ -245,6 +245,7 @@ float3 SampleDDGIIrradianceCascade(DDGIData data, Texture2D<snorm float4> probes
         {
             float variance = abs(Square(probeDistance.x) - probeDistance.y);
             float visibilityWeight = variance / (variance + Square(biasedPosToProbeDist - probeDistance.x));
+            visibilityWeight = lerp(1, visibilityWeight, data.IndirectShadowsStrength);
             weights *= max(visibilityWeight * visibilityWeight * visibilityWeight, 0.0f);
         }
 
@@ -294,7 +295,8 @@ float3 SampleDDGIIrradianceCascade(DDGIData data, Texture2D<snorm float4> probes
 #if !DDGI_FALLBACK_OUTER_DEDICATED_PROBE
     canNormalize += invalidCascade ? 1 : 0; // Normalize when outside the last cascade to preserve ambient GI when not using ambient probe
 #endif
-    totalIrradiance.rgb /= lerp(1, totalIrradiance.a, saturate(canNormalize));
+    float shadowNormalization = lerp(1, totalIrradiance.a, saturate(canNormalize));
+    totalIrradiance.rgb /= lerp(totalIrradiance.a, shadowNormalization, data.IndirectShadowsStrength);
     if (fallbacks >= 5 && totalIrradianceNonDir.a > 0.00001f)
     {
         // Use non-directional irradiance when sampling mostly fallback probes (out of place)