Refactor arc shader so it uses only matrix uniform

shader/twoD/arc.frag

@@ -1,34 +1,34 @@
 #version 430 core
 in vec4 gColor;
-in vec2 cenPosT;
 in float gRadIn;
-in float gRadOut;
 in vec2 angles;
+in vec2 dist;
 out vec4 fColor;
-out float gl_FragDepth;
 
-uniform float rotation;
+//uniform float rotation;
 
 void main()
 {
-  vec2 pos = gl_FragCoord.xy;
-  float d = distance(pos,cenPosT);
-  float dTest = max ( step(gRadOut/2,d)
-                    , 1 - step(gRadIn/2,d)
-                    );
-
-  vec2 posDiff = pos - cenPosT;
-  float sa = angles.x - rotation;
+//  vec2 pos = gl_FragCoord.xy;
+//  float d = distance(pos,cenPosT);
+//  float dTest = max ( step(gRadOut/2,d)
+//                    , 1 - step(gRadIn/2,d)
+//                    );
+//
+//  vec2 posDiff = pos - cenPosT;
+  float sa = angles.x;
   vec2 sv = vec2 (-sin(sa), cos(sa));
-  float saTest = dot(sv,posDiff) >= 0 ? 0 : 1;
-  float ea = angles.y - rotation;
+//  float saTest = dot(sv,posDiff) >= 0 ? 0 : 1;
+  float ea = angles.y;
   vec2 ev = vec2 (-sin(ea), cos(ea));
-  float eaTest = dot(ev,posDiff) <= 0 ? 0 : 1;
-  float aTest = ea - sa < radians(180) ? max (saTest,eaTest) 
-                                       : min (saTest,eaTest);
-
-  float onArcTest = max(dTest,aTest); 
-
-  gl_FragDepth = max(gl_FragCoord.z , onArcTest);
+//  float eaTest = dot(ev,posDiff) <= 0 ? 0 : 1;
+//  float aTest = ea - sa < radians(180) ? max (saTest,eaTest) 
+//                                       : min (saTest,eaTest);
+//
+//  float onArcTest = max(dTest,aTest); 
+//
+//  gl_FragDepth = max(gl_FragCoord.z , onArcTest);
+ float d = (dist.x * dist.x) + (dist.y * dist.y);
+  if (d > 1 || d < gRadIn || dot(sv, dist) < 0 || dot(ev, dist) > 0) {discard;}
   fColor = gColor;
 }