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ScriptableRenderPipeline/HDRenderPipeline/Material/Lit/Resources/SubsurfaceScattering.compute

         uint2 quadCoord;
 
         // The traversal order is such that the quad's X coordinate is monotonically increasing.
+        // The corner is always the near the block of the corresponding wavefront.
-            case 0:
+            case 0:  // Bottom left
-            case 1:
+            case 1:  // Bottom right
-            case 2:
+            case 2:  // Top left
-            default: // 3
+            default: // Top right
                 quadCoord.x = min(quadIndex, halfCacheWidthInQuads - 1);
                 quadCoord.y = min(halfCacheWidthInQuads - 1, 2 * (halfCacheWidthInQuads - 1) - quadIndex);
                 break;