Debug bezier quad, doesn't draw straighter lines well

shader/bezierQuad.frag

@@ -23,10 +23,7 @@ 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;
-  if ( d < 0 || e > 0) { discard; }
+//  if ( d < 0 || e > 0) { discard; }
   fColor = gColor;
-//  if ( d < 0) { fColor = vec4 (0,1,0,1); }
-//  if ( e > 0) { fColor = vec4 (0,0,1,1); }
-//  if ( d < z*z*0.0 || d > z*z*0.1+ 0.5) { fColor = vec4 (0,1,0,1); }
-//  if ( d < -0.1 || d > 0.1) { fColor = vec4 (0,0,1,1); }
+  if ( d < 0 || e > 0) { fColor = vec4(0,0,1,1); }
 }

shader/bezierQuad.geom

@@ -1,6 +1,6 @@
 #version 430 core
 layout (triangles) in;
-layout (triangle_strip, max_vertices = 3) out;
+layout (triangle_strip, max_vertices = 4) out;
 in vec4 vColor[];
 in float vRad[];
 out vec4 gColor;
@@ -8,6 +8,10 @@ out float gRadStart;
 out float gRadEnd;
 out vec3 gBoundingBox;
 
+vec3 normV (vec3 v)
+{   return vec3(v.y,-v.x,v.z) ;
+}
+
 void main()
 {
   vec3 pa = gl_in[0].gl_Position.xyz;
@@ -16,11 +20,12 @@ void main()
 
   gRadStart = vRad[0];
   gRadEnd   = vRad[2];
-//  vec3 pa = vec3(paa.xy + 0.1 * (paa.xy - pca.xy), paa.z);
-//  vec3 pc = vec3(pca.xy + 0.1 * (pca.xy - paa.xy), pca.z);
+
 
   gBoundingBox = vec3 (1,0,1);
   gColor = vColor[0];
+  gl_Position = vec4 (pa + normV (pa-pb) , 1);
+  EmitVertex();
   gl_Position = vec4 (pa, 1);
   EmitVertex();
   gBoundingBox = vec3 (0,0,0);