Store material in fluid buffer and improve visualization

Replaces the density value which is actually not that useful for visualization.

Encoding integer values as floats by casting and comparing them using
exact floating point comparison is not very safe but works out for now.

3 files changed, 36 insertions, 37 deletions

diff --git a/src/shader/code/collide.glsl b/src/shader/code/collide.glsl
index 182f5bd..3f4e2c5 100644
--- a/src/shader/code/collide.glsl
+++ b/src/shader/code/collide.glsl
@@ -6,7 +6,6 @@ layout (local_size_x = 1, local_size_y = 1) in;
 layout (std430, binding=1) buffer bufferCollide  { float collideCells[];  };
 layout (std430, binding=2) buffer bufferStream   { float streamCells[];   };
 layout (std430, binding=3) buffer bufferFluid    { float fluidCells[];    };
-layout (std430, binding=4) buffer bufferGeometry { int   materialCells[]; };
 
 /// external influence
 
@@ -70,29 +69,22 @@ void set(uint x, uint y, int i, int j, float v) {
 	collideCells[indexOfLatticeCell(x,y) + indexOfDirection(i,j)] = v;
 }
 
-void setFluid(uint x, uint y, vec2 v, float d) {
+void setFluid(uint x, uint y, vec2 v) {
 	const uint idx = indexOfFluidVertex(x, y);
 	fluidCells[idx + 0] = v.x;
 	fluidCells[idx + 1] = v.y;
-	fluidCells[idx + 2] = d;
 }
 
 int getMaterial(uint x, uint y) {
-	return materialCells[nX*y + x];
+	const uint idx = indexOfFluidVertex(x, y);
+	return int(fluidCells[idx + 2]);
 }
 
 void setMaterial(uint x, uint y, int m) {
-	materialCells[nX*y + x] = m;
-}
-
-void disableFluid(uint x, uint y) {
 	const uint idx = indexOfFluidVertex(x, y);
-	fluidCells[idx + 0] = 0.0;
-	fluidCells[idx + 1] = 0.0;
-	fluidCells[idx + 2] = -2.0;
+	fluidCells[idx + 2] = m;
 }
 
-
 /// Moments
 
 float density(uint x, uint y) {
@@ -125,7 +117,7 @@ void disableWallInterior(uint x, uint y) {
 	for ( int i = -1; i <= 1; ++i ) {
 		for ( int j = -1; j <= 1; ++j ) {
 			const int material = getMaterial(x+i,y+j);
-			if ( material  == 0 || material == 2 ) {
+			if ( material  == 0 || material == 2 || material == 3 ) {
 				++wallNeighbors;
 			}
 		}
@@ -139,7 +131,7 @@ void disableWallInterior(uint x, uint y) {
 /// Determine external influence
 
 float getExternalPressureInflux(uint x, uint y) {
-	if ( mouseState == 1 && norm(vec2(x,y) - mousePos) < 3 ) {
+	if ( mouseState == 1 && norm(vec2(x,y) - mousePos) < 2 ) {
 		return 1.5;
 	} else {
 		return 0.0;
@@ -147,7 +139,7 @@ float getExternalPressureInflux(uint x, uint y) {
 }
 
 bool isWallRequestedAt(uint x, uint y) {
-	if ( mouseState == 2 && norm(vec2(x,y) - mousePos) < 3 ) {
+	if ( mouseState == 2 && norm(vec2(x,y) - mousePos) < 2 ) {
 		return true;
 	} else {
 		return false;
@@ -164,14 +156,14 @@ void main() {
 		return;
 	}
 
-	if ( isWallRequestedAt(x,y) ) {
-		setMaterial(x,y,2);
-		disableFluid(x,y);
-	}
-
 	const int material = getMaterial(x,y);
 
-	if ( material == 2 ) { // wall
+	if ( isWallRequestedAt(x,y) && material == 1 ) {
+		setMaterial(x,y,3);
+		return;
+	}
+
+	if ( material == 3 ) { // manually added wall
 		disableWallInterior(x,y);
 	}
 
@@ -179,7 +171,7 @@ void main() {
 		const float d = max(getExternalPressureInflux(x,y), density(x,y));
 		const vec2  v = velocity(x,y,d);
 
-		setFluid(x,y,v,d);
+		setFluid(x,y,v);
 
 		for ( int i = -1; i <= 1; ++i ) {
 			for ( int j = -1; j <= 1; ++j ) {
diff --git a/src/shader/code/stream.glsl b/src/shader/code/stream.glsl
index a8aec1d..59aed98 100644
--- a/src/shader/code/stream.glsl
+++ b/src/shader/code/stream.glsl
@@ -5,7 +5,7 @@ layout (local_size_x = 1, local_size_y = 1) in;
 
 layout (std430, binding=1) buffer bufferCollide  { float collideCells[];  };
 layout (std430, binding=2) buffer bufferStream   { float streamCells[];   };
-layout (std430, binding=4) buffer bufferGeometry { int   materialCells[]; };
+layout (std430, binding=3) buffer bufferFluid    { float fluidCells[];    };
 
 /// LBM constants
 
@@ -24,6 +24,10 @@ uint indexOfLatticeCell(uint x, uint y) {
 	return q*nX*y + q*x;
 }
 
+uint indexOfFluidVertex(uint x, uint y) {
+	return 3*nX*y + 3*x;
+}
+
 /// Data access
 
 float get(uint x, uint y, int i, int j) {
@@ -35,17 +39,8 @@ void set(uint x, uint y, int i, int j, float v) {
 }
 
 int getMaterial(uint x, uint y) {
-	return materialCells[nX*y + x];
-}
-
-/// Domain description
-
-bool isEndOfWorld(uint x, uint y) {
-	return x == 0 || x == nX-1 || y == 0 || y == nY-1;
-}
-
-bool isOuterWall(uint x, uint y) {
-	return x == 1 || x == nX-2 || y == 1 || y == nY-2;
+	const uint idx = indexOfFluidVertex(x, y);
+	return int(fluidCells[idx + 2]);
 }
 
 /// Boundary conditions
@@ -74,7 +69,7 @@ void main() {
 		return;
 	}
 
-	if ( material == 2 ) {
+	if ( material == 2 || material == 3 ) {
 		bounceBack(x,y);
 	}
 
diff --git a/src/shader/code/vertex.glsl b/src/shader/code/vertex.glsl
index 69bbaef..e0ce9a8 100644
--- a/src/shader/code/vertex.glsl
+++ b/src/shader/code/vertex.glsl
@@ -32,6 +32,14 @@ vec2 fluidVertexAtIndex(uint i) {
 	);
 }
 
+bool isInactive(int material) {
+	return material == 0;
+}
+
+bool isWallFrontier(int material) {
+	return material == 2 || material == 3;
+}
+
 void main() {
 	const vec2 idx = fluidVertexAtIndex(gl_VertexID);
 
@@ -42,13 +50,17 @@ void main() {
 		1.
 	);
 
-	if ( VertexPosition.z < -1.0 ) {
+	const int material = int(round(VertexPosition.z));
+
+	if ( isInactive(material) ) {
+		vs_out.color = vec3(0.5, 0.5, 0.5);
+	} else if ( isWallFrontier(material) ) {
 		vs_out.color = vec3(0.0, 0.0, 0.0);
 	} else {
 		vs_out.color = mix(
 			vec3(-0.5, 0.0, 1.0),
 			vec3( 1.0, 0.0, 0.0),
-			displayAmplifier * VertexPosition.z * norm(VertexPosition.xy)
+			displayAmplifier * norm(VertexPosition.xy)
 		);
 	}
 }