PT: improved SHARC usage (better IQ for single bounce reflections and glass)

Author: dzhdanNV

Shaders/TraceOpaque.cs.hlsl

@@ -172,7 +172,7 @@ TraceOpaqueResult TraceOpaque( GeometryProps geometryProps0, MaterialProps mater
     sharcParams.resolvedBuffer = gInOut_SharcResolved;
 
     #if( USE_SHARC_DEBUG == 2 )
-        result.diffRadiance = HashGridDebugColoredHash( sharcHitData.positionWorld, hashGridParams );
+        result.diffRadiance = HashGridDebugColoredHash( sharcHitData.positionWorld, sharcHitData.normalWorld, hashGridParams );
     #else
         bool isValid = SharcGetCachedRadiance( sharcParams, sharcHitData, result.diffRadiance, true );
 
@@ -349,10 +349,9 @@ TraceOpaqueResult TraceOpaque( GeometryProps geometryProps0, MaterialProps mater
                     rndScaled *= USE_SHARC_DITHERING;
 
                     float3x3 mBasis = Geometry::GetBasis( geometryProps.N );
-                    Xglobal += mBasis[ 0 ] * rndScaled.x + mBasis[ 1 ] * rndScaled.y;
+                    float3 jitter = mBasis[ 0 ] * rndScaled.x + mBasis[ 1 ] * rndScaled.y;
 
                     SharcHitData sharcHitData;
-                    sharcHitData.positionWorld = Xglobal;
                     sharcHitData.materialDemodulation = GetMaterialDemodulation( geometryProps, materialProps );
                     sharcHitData.normalWorld = geometryProps.N;
                     sharcHitData.emissive = materialProps.Lemi;
@@ -374,9 +373,24 @@ TraceOpaqueResult TraceOpaque( GeometryProps geometryProps0, MaterialProps mater
                     isSharcAllowed &= Rng::Hash::GetFloat( ) < ( bounce == gBounceNum ? 1.0 : footprintNorm ); // is voxel size acceptable?
                     isSharcAllowed &= gSHARC && NRD_MODE < OCCLUSION; // trivial
 
-                    float3 sharcRadiance;
-                    if( isSharcAllowed && SharcGetCachedRadiance( sharcParams, sharcHitData, sharcRadiance, false ) )
-                        Lcached = float4( sharcRadiance, 1.0 );
+                    if( isSharcAllowed )
+                    {
+                        // Try jittered position
+                        float3 sharcRadiance;
+
+                        sharcHitData.positionWorld = Xglobal + jitter;
+                        bool isFound = SharcGetCachedRadiance( sharcParams, sharcHitData, sharcRadiance, false );
+
+                        if( !isFound )
+                        {
+                            // Slipped out of the surface or mismatched normals, try non-jittered position
+                            sharcHitData.positionWorld = Xglobal;
+                            isFound = SharcGetCachedRadiance( sharcParams, sharcHitData, sharcRadiance, false );
+                        }
+
+                        if( isFound )
+                            Lcached = float4( sharcRadiance, 1.0 );
+                    }
 
                     // Cache miss - compute lighting, if not found in caches
                     if( Rng::Hash::GetFloat( ) > Lcached.w )

Shaders/TraceTransparent.cs.hlsl

@@ -118,10 +118,9 @@ float3 TraceTransparent( TraceTransparentDesc desc )
         rndScaled *= USE_SHARC_DITHERING * float( USE_SHARC_DEBUG == 0 );
 
         float3x3 mBasis = Geometry::GetBasis( geometryProps.N );
-        Xglobal += mBasis[ 0 ] * rndScaled.x + mBasis[ 1 ] * rndScaled.y;
+        float3 jitter = mBasis[ 0 ] * rndScaled.x + mBasis[ 1 ] * rndScaled.y;
 
         SharcHitData sharcHitData;
-        sharcHitData.positionWorld = Xglobal;
         sharcHitData.materialDemodulation = GetMaterialDemodulation( geometryProps, materialProps );
         sharcHitData.normalWorld = geometryProps.N;
         sharcHitData.emissive = materialProps.Lemi;
@@ -141,9 +140,24 @@ float3 TraceTransparent( TraceTransparentDesc desc )
         bool isSharcAllowed = Rng::Hash::GetFloat( ) > Lcached.w; // is needed?
         isSharcAllowed &= gSHARC && NRD_MODE < OCCLUSION; // trivial
 
-        float3 sharcRadiance;
-        if (isSharcAllowed && SharcGetCachedRadiance( sharcParams, sharcHitData, sharcRadiance, false))
-            Lcached = float4( sharcRadiance, 1.0 );
+        if( isSharcAllowed )
+        {
+            // Try jittered position
+            float3 sharcRadiance;
+
+            sharcHitData.positionWorld = Xglobal + jitter;
+            bool isFound = SharcGetCachedRadiance( sharcParams, sharcHitData, sharcRadiance, false );
+
+            if( !isFound )
+            {
+                // Slipped out of the surface or mismatched normals, try non-jittered position
+                sharcHitData.positionWorld = Xglobal;
+                isFound = SharcGetCachedRadiance( sharcParams, sharcHitData, sharcRadiance, false );
+            }
+
+            if( isFound )
+                Lcached = float4( sharcRadiance, 1.0 );
+        }
 
         // Cache miss - compute lighting, if not found in caches
         if( Rng::Hash::GetFloat( ) > Lcached.w )