Improve abdbd1ee64 to better handle cascade transitions

Source/Shaders/GlobalSignDistanceField.hlsl

@@ -215,35 +215,37 @@ GlobalSDFHit RayTraceGlobalSDF(const GlobalSDFData data, Texture3D<float> tex, T
     hit.HitTime = -1.0f;
     float chunkSizeDistance = (float)GLOBAL_SDF_RASTERIZE_CHUNK_SIZE / data.Resolution; // Size of the chunk in SDF distance (0-1)
     float chunkMarginDistance = (float)GLOBAL_SDF_RASTERIZE_CHUNK_MARGIN / data.Resolution; // Size of the chunk margin in SDF distance (0-1)
-    float nextIntersectionStart = 0.0f;
+    float nextIntersectionStart = trace.MinDistance;
     float traceMaxDistance = min(trace.MaxDistance, data.CascadePosDistance[3].w * 2);
     float3 traceEndPosition = trace.WorldPosition + trace.WorldDirection * traceMaxDistance;
+    LOOP
     for (uint cascade = 0; cascade < data.CascadesCount && hit.HitTime < 0.0f; cascade++)
     {
         float4 cascadePosDistance = data.CascadePosDistance[cascade];
         float voxelSize = data.CascadeVoxelSize[cascade];
         float voxelExtent = voxelSize * 0.5f;
-        float3 worldPosition = trace.WorldPosition + trace.WorldDirection * max(voxelSize * cascadeTraceStartBias, trace.MinDistance);
+        float3 worldPosition = trace.WorldPosition;
+
+        // Skip until cascade that contains the start location
+        if (any(abs(worldPosition - cascadePosDistance.xyz) > cascadePosDistance.w))
+            continue;
 
         // Hit the cascade bounds to find the intersection points
+        float traceStartBias = voxelSize * cascadeTraceStartBias;
         float2 intersections = LineHitBox(worldPosition, traceEndPosition, cascadePosDistance.xyz - cascadePosDistance.www, cascadePosDistance.xyz + cascadePosDistance.www);
         intersections.xy *= traceMaxDistance;
+        intersections.x = max(intersections.x, traceStartBias);
         intersections.x = max(intersections.x, nextIntersectionStart);
-        if (intersections.x >= intersections.y)
+        if (intersections.x < intersections.y)
         {
-            // Skip the current cascade if the ray starts outside it
+            // Skip the current cascade tracing on the next cascade
-            continue;
+            nextIntersectionStart = max(nextIntersectionStart, intersections.y - voxelSize);
-        }
-
-        // Skip the current cascade tracing on the next cascade (if we're tracing from inside SDF volume)
-        if (intersections.x <= 0.0f)
-            nextIntersectionStart = intersections.y;
 
             // Walk over the cascade SDF
             uint step = 0;
             float stepTime = intersections.x;
             LOOP
-        for (; step < 250 && stepTime < intersections.y; step++)
+            for (; step < 250 && stepTime < intersections.y && hit.HitTime < 0.0f; step++)
             {
                 float3 stepPosition = worldPosition + trace.WorldDirection * stepTime;
 
@@ -287,7 +289,6 @@ GlobalSDFHit RayTraceGlobalSDF(const GlobalSDFData data, Texture3D<float> tex, T
                         float zn = tex.SampleLevel(SamplerLinearClamp, float3(textureUV.x, textureUV.y, textureUV.z - texelOffset), 0).x;
                         hit.HitNormal = normalize(float3(xp - xn, yp - yn, zp - zn));
                     }
-                break;
                 }
 
                 // Move forward
@@ -295,6 +296,7 @@ GlobalSDFHit RayTraceGlobalSDF(const GlobalSDFData data, Texture3D<float> tex, T
             }
             hit.StepsCount += step;
         }
+    }
     return hit;
 }