Working radial distortion

shader/texture/barrel.frag

@@ -1,18 +1,25 @@
 #version 430 core
-in vec2 cenPos;
 in vec2 texPos;
 in vec2 texDist;
-in float factor;
+in float gfactor;
+in vec2 vcpos;
 out vec4 fColor;
 layout (binding = 1) uniform sampler2D screenTexture;
 float f ( float x) {
- return max (1, 1 / (2 * x + 0.5)) ;
-// return min (1, x) ;
+ //return max (1, 1 / (2 * x + 0.5)) ;
+ //return min (1, x) ;
+ if (x>1) {return 1;} else {return (1-gfactor)*x + gfactor;}
+ //if (x>1) {return 1;} else {return 0.5;}
 }
 void main()
 {
-    vec4 tColor = vec4(texture(screenTexture , texPos) );
-    float t = distance(cenPos,texDist);
-    fColor = vec4(tColor.xy,t,tColor.w);
-      //, cenPos + f(distance(cenPos,texDist)) * (texPos - cenPos))) ;
+    float t = f(length(texDist));
+    fColor = vec4(texture(screenTexture 
+                , 0.5+0.5 *( vcpos + t * (texPos - vcpos))
+                ) 
+                );
+    //vec4 tColor = vec4(texture(screenTexture , cpos + (texPos - cpos)) );
+    //float t = distance(cenPos,texPos);
+    //fColor = vec4(tColor.xy,t,tColor.w);
+    //fColor = tColor;
 }