Approximate curl only if all bases are fluid

2 files changed, 15 insertions, 1 deletions

diff --git a/src/shader/code/collide.glsl b/src/shader/code/collide.glsl
index d32bf78..0f9b2bd 100644
--- a/src/shader/code/collide.glsl
+++ b/src/shader/code/collide.glsl
@@ -133,7 +133,7 @@ float equilibrium(float d, vec2 v, int i, int j) {
 /// Material number meaning (geometry is only changed by the interaction shader)
 
 bool isBulkFluidCell(int material) {
-	return material == 1 || material == 4 || material == 5 || material == 6;
+	return material == 1 || material == 5 || material == 6;
 }
 
 bool isBounceBackCell(int material) {
diff --git a/src/shader/code/extra.glsl b/src/shader/code/extra.glsl
index 3fec976..b8483ae 100644
--- a/src/shader/code/extra.glsl
+++ b/src/shader/code/extra.glsl
@@ -23,6 +23,11 @@ uint indexOfFluidVertex(uint x, uint y) {
 
 /// Data access
 
+int getMaterial(uint x, uint y) {
+	const uint idx = indexOfFluidVertex(x, y);
+	return int(extraCells[idx + 2]);
+}
+
 vec2 getFluidVelocity(uint x, uint y) {
 	const uint idx = indexOfFluidVertex(x, y);
 	return vec2(
@@ -44,6 +49,15 @@ void main() {
 		return;
 	}
 
+	if ( getMaterial(x,y)   != 1
+	  || getMaterial(x-1,y) != 1
+	  || getMaterial(x+1,y) != 1
+	  || getMaterial(x,y-1) != 1
+	  || getMaterial(x,y+1) != 1 ) {
+		setFluidExtra(x, y,	0.0);
+		return;
+	}
+
 	// simple central difference discretization of the 2d curl operator
 	const float dxvy = (getFluidVelocity(x+1,y).y - getFluidVelocity(x-1,y).y)
 	                 / (2*convLength);