Purify collide shader

i.e. move fluid vertex placement to appropriate vertex shader.
     Do not amplify or shift fluid moments in any way prior to
     passing it to the display pipeline.

1 files changed, 24 insertions, 2 deletions

diff --git a/src/shader/code/vertex.glsl b/src/shader/code/vertex.glsl
index 516f2c6..e132e5f 100644
--- a/src/shader/code/vertex.glsl
+++ b/src/shader/code/vertex.glsl
@@ -7,6 +7,11 @@ out VS_OUT {
 	vec3 color;
 } vs_out;
 
+uniform uint nX;
+uniform uint nY;
+
+const float displayAmplifier = 10.0;
+
 float unit(float x) {
 	return 1.0/(1.0+exp(-x));
 }
@@ -15,8 +20,25 @@ vec3 getColor(float x) {
 	return x*vec3(1.0,0.0,0.0) + (1-x)*vec3(-0.5,0.0,1.0);
 }
 
+vec2 fluidVertexAtIndex(uint i) {
+	const float y = floor(float(i) / float(nX));
+	return vec2(
+		i - nX*y,
+		y
+	);
+
+}
+
 void main() {
-	gl_Position  = vec4(VertexPosition.xy, 0., 1.);
-	vs_out.color = getColor(unit(VertexPosition.z));
+	const vec2 idx = fluidVertexAtIndex(gl_VertexID);
+
+	gl_Position  = vec4(
+		idx.x - nX/2,
+		idx.y - nY/2,
+		0.,
+		1.
+	);
+
+	vs_out.color = getColor(unit(displayAmplifier * VertexPosition.z));
 }
 )";