Implement multiple radial distortion rendering

shader/texture/barrel.geom

@@ -9,7 +9,6 @@ out vec2 vcpos;
 out vec2 texPos;
 out vec2 texDist;
 out float gfactor;
-
 vec2 g(float x,float y, vec2 v, vec2 r1, vec2 r2)
     { return vec2 
         (dot(normalize(r1-v),vec2(x,y)-v) / length(r1-v)
@@ -18,7 +17,6 @@ vec2 g(float x,float y, vec2 v, vec2 r1, vec2 r2)
     }
 void main() {
   vec2 cpos = vCen[0];
-  //vcpos = 2*cpos - vec2(1,1);
   vcpos = cpos;
   vec2 grad1 = vRad1[0];
   vec2 grad2 = vRad2[0];