[Fogbugz # 1386436] Fixing FPTL failing when near and far are very tight. #6826

Author: kecho

com.unity.render-pipelines.high-definition/CHANGELOG.md

@@ -22,6 +22,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - Fixed Post Process not editable in the default frame settings.
 - Fixed errors spamming when in player mode due to ray tracing light cluster debug view (case 1390471).
 - Fixed missing unit in ray tracing related tooltips and docs (case 1397491).
+- Fixed artifacts on gpu light culling when the frustum near and far are very spread out (case 1386436)
 
 ## [12.1.4] - 2021-12-07
 

com.unity.render-pipelines.high-definition/Runtime/Lighting/LightLoop/lightlistbuild.compute

@@ -454,7 +454,7 @@ void FinePruneLights(uint threadID, int iNrCoarseLights, uint2 viTilLL, float vL
         {
             LightVolumeData lightData = _LightVolumeData[idxCoarse];
             const bool bIsSpotDisc = true; // (lightData.flags&IS_CIRCULAR_SPOT_SHAPE) != 0;
-            for(int i=0; i<PIXEL_PER_THREAD && !lightValid; i++)
+            for(int i=0; i<PIXEL_PER_THREAD; i++)
             {
                 int idx = t + i*NR_THREADS;
 
@@ -477,12 +477,14 @@ void FinePruneLights(uint threadID, int iNrCoarseLights, uint2 viTilLL, float vL
 #else
                 lightValid = isValid;
 #endif
+                if (isValid)
+                    break;
             }
         }
         else if (uLightVolume == LIGHTVOLUMETYPE_SPHERE)
         {
             LightVolumeData lightData = _LightVolumeData[idxCoarse];
-            for(int i=0; i<PIXEL_PER_THREAD && !lightValid; i++)
+            for(int i=0; i<PIXEL_PER_THREAD; i++)
             {
                 int idx = t + i*NR_THREADS;
 
@@ -500,12 +502,14 @@ void FinePruneLights(uint threadID, int iNrCoarseLights, uint2 viTilLL, float vL
 #else
                 lightValid = isValid;
 #endif
+                if (isValid)
+                    break;
            }
         }
         else if (uLightVolume ==  LIGHTVOLUMETYPE_BOX)
         {
             LightVolumeData lightData = _LightVolumeData[idxCoarse];
-            for(int i=0; i<PIXEL_PER_THREAD && !lightValid; i++)
+            for(int i=0; i<PIXEL_PER_THREAD; i++)
             {
                 int idx = t + i*NR_THREADS;
 
@@ -523,6 +527,8 @@ void FinePruneLights(uint threadID, int iNrCoarseLights, uint2 viTilLL, float vL
 #else
                 lightValid = isValid;
 #endif
+                if (isValid)
+                    break;
             }
         }
         else