idk

res/shaders/fluid/SignedDistance.slang

@@ -31,17 +31,17 @@ void reinitialize(uint3 dispatchThreadID : SV_DispatchThreadID)
     float dx = 1.0f;
 
     // Current value and original sign
-    float p = phi[x, y, z];
+    float p = phi0[x, y, z];
     float s = smoothSign(phi0[x, y, z], dx);
 
-    // Upwind finite differences for |grad phi|
+    // Upwind finite differences for |grad phi| — read from snapshot to avoid race
     // Forward and backward differences
-    float dxp = phi[x + 1, y, z] - p;
-    float dxm = p - phi[x - 1, y, z];
-    float dyp = phi[x, y + 1, z] - p;
-    float dym = p - phi[x, y - 1, z];
-    float dzp = phi[x, y, z + 1] - p;
-    float dzm = p - phi[x, y, z - 1];
+    float dxp = phi0[x + 1, y, z] - p;
+    float dxm = p - phi0[x - 1, y, z];
+    float dyp = phi0[x, y + 1, z] - p;
+    float dym = p - phi0[x, y - 1, z];
+    float dzp = phi0[x, y, z + 1] - p;
+    float dzm = p - phi0[x, y, z - 1];
 
     // Godunov upwind scheme
     float gradPhi;