Add shaders that will just return positional information

shader/posTwoD/bezierQuad.frag

@@ -0,0 +1,16 @@
+#version 430 core
+in vec4 vColor;
+in vec2 boxOut;
+in vec2 boxIn;
+
+out vec4 fColor;
+
+void main()
+{
+  //float d = x - y - 1 + 2* sqrt(y);
+  float d = sqrt(boxOut.x) + sqrt(boxOut.y) - 1.0;
+//  float e = sqrt(f(x,wStart)) + sqrt(f(y,wEnd)) - 1.0;
+  float e = sqrt(boxIn.x) + sqrt(boxIn.y) - 1.0;
+  if ( d < 0 || e > 0) { discard; }
+  fColor = vColor;
+}