Improve bezier curve rendering

shader/bezierQuad.frag

@@ -1,8 +1,8 @@
 #version 430 core
 in vec4 gColor;
 in vec3 gBoundingBox;
-in float gRadStart;
-in float gRadEnd;
+in float wStart;
+in float wEnd;
 
 out vec4 fColor;
 
@@ -10,9 +10,6 @@ float x = gBoundingBox.x;
 float y = gBoundingBox.y;
 float z = gBoundingBox.z;
 
-float w = gRadEnd;
-float w2 = gRadStart;
-
 float f (float a, float b)
 {   
     float c = 1 / (1 - 2*b) ;
@@ -22,7 +19,7 @@ void main()
 {
   //float d = x - y - 1 + 2* sqrt(y);
   float d = sqrt(x) + sqrt(y) - 1;
-  float e = sqrt(f(x,w)) + sqrt(f(y,w2)) - 1.0;
+  float e = sqrt(f(x,wStart)) + sqrt(f(y,wEnd)) - 1.0;
 //  if ( d < 0 || e > 0) { discard; }
   fColor = gColor;
   if ( d < 0 || e > 0) { fColor = vec4(0,0,1,1); }

shader/bezierQuad.geom

@@ -2,10 +2,11 @@
 layout (triangles) in;
 layout (triangle_strip, max_vertices = 5) out;
 in vec4 vColor[];
-in float vRad[];
+in vec2 vPosOff[];
+in float vRadMag[];
 out vec4 gColor;
-out float gRadStart;
-out float gRadEnd;
+out float wStart;
+out float wEnd;
 out vec3 gBoundingBox;
 
 vec2 normV2 (vec2 v)
@@ -21,21 +22,16 @@ void main()
   vec3 pb = gl_in[1].gl_Position.xyz;
   vec3 pc = gl_in[2].gl_Position.xyz;
 
-  gRadStart = vRad[0];
-  gRadEnd   = vRad[2];
-
-  vec2 ab = (pa.xy - pb.xy);
-  vec2 cb = (pc.xy - pb.xy);
-  float dir = lhs( cb,ab);
+  wStart = vRadMag [0];
+  wEnd   = vRadMag [2];
 
   gBoundingBox = vec3 (0.9,0.1,0);
   gColor = vColor[0];
-  gl_Position = vec4 (pa.xy + dir * 2 * gRadStart * normV2(ab) , pa.z , 1);
+  gl_Position = vec4 (vPosOff[0] , pa.z , 1);
   EmitVertex();
   gBoundingBox = vec3 (0.1,0.9,0);
   gColor = vColor[2];
-//  gl_Position = vec4 (pc.xy + dir * gRadEnd * (normV2 (pb.xy-pc.xy)), pa.z , 1);
-  gl_Position = vec4 (pc.xy - dir * 2 * gRadEnd * normV2(cb) , pc.z , 1);
+  gl_Position = vec4 (vPosOff[2] , pc.z , 1);
   EmitVertex();
   gBoundingBox = vec3 (1,0,1);
   gColor = vColor[0];

shader/bezierQuad.vert

@@ -1,9 +1,10 @@
 #version 430 core
 layout (location = 0) in vec3 position;
 layout (location = 1) in vec4 color;
-layout (location = 2) in float rad;
+layout (location = 2) in vec3 radVec;
 out vec4 vColor;
-out float vRad;
+out vec2 vPosOff;
+out float vRadMag;
 
 uniform vec2 winSize;
 uniform float zoom;
@@ -14,6 +15,7 @@ uniform mat4 worldMat;
 void main()
 {
   gl_Position = worldMat * vec4(position.xyz,1);
-  vColor = color;
-  vRad   = rad;
+  vColor  = color;
+  vPosOff = ( worldMat * vec4(radVec.xy,0,1) ).xy ;
+  vRadMag = radVec.z ;
 }