Work on distortion shader

shader/texture/barrel.frag

@@ -1,10 +1,23 @@
 #version 450 core
 in vec2 texPos;
 in vec2 distmask;
+in vec2 pinch;
 out vec4 fColor;
 layout (binding = 1) uniform sampler2D screenTexture;
-float x = min(1, dot(distmask,distmask));
+float x = 1 - min(1, dot(distmask,distmask));
+float xab = abs(distmask.x);
+float yab = abs(distmask.y);
 void main()
 {
-    fColor = mix(texture(screenTexture, texPos),vec4(1,0,0,1),x);
+    fColor = (xab < 1 && yab < 1 
+            //? vec4 (0.5*(distmask.x+1),0.5*(distmask.y+1),0,1) 
+            ? vec4 (0.5*(distmask.x+1),0.5*(distmask.y+1),0,1) 
+            : texture(screenTexture, texPos));
+    //fColor = texture(screenTexture, (texPos + x*x*pinch));
+    //fColor = vec4
+    //    ( texture(screenTexture, (texPos + x*x*pinch)).r
+    //    , texture(screenTexture, (texPos - x*x*pinch)).g
+    //    , texture(screenTexture, (texPos - x*x*(pinch.yx))).b
+    //    , texture(screenTexture, texPos).a
+    //    ) ;
 }

shader/texture/barrel.geom

@@ -1,44 +0,0 @@
-#version 450 core
-layout (points) in;
-layout (triangle_strip, max_vertices = 4) out;
-in vec2 vRad1[];
-in vec2 vRad2[];
-in vec2 vCen[];
-in float vFactor[];
-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)
-        ,dot(normalize(r2-v),vec2(x,y)-v) / length(r2-v)
-        ); 
-    }
-void main() {
-  vec2 cpos = vCen[0];
-  vcpos = cpos;
-  vec2 grad1 = vRad1[0];
-  vec2 grad2 = vRad2[0];
-  gfactor = vFactor[0];
-  texPos = vec2(1,1);
-  texDist = g(1,1,cpos,grad1,grad2);
-  gl_Position = vec4 (1,1,0,1);
-  EmitVertex();
-  texPos = vec2(1,0);
-  texPos = vec2(1,-1);
-  texDist = g(1,-1,cpos,grad1,grad2);
-  gl_Position = vec4 (1,-1,0,1);
-  EmitVertex();
-  texPos = vec2(0,1);
-  texPos = vec2(-1,1);
-  texDist = g(-1,1,cpos,grad1,grad2);
-  gl_Position = vec4 (-1,1,0,1);
-  EmitVertex();
-  texPos = vec2(0,0);
-  texPos = vec2(-1,-1);
-  texDist = g(-1,-1,cpos,grad1,grad2);
-  gl_Position = vec4 (-1,-1,0,1);
-  EmitVertex();
-  EndPrimitive();
-}

shader/texture/barrel.vert

@@ -1,9 +1,10 @@
 #version 450 core
-struct DataS { vec2 pos; vec2 rad1; vec2 rad2; };
+struct DataS { vec2 pos; vec2 v1; vec2 v2; vec2 rad; };
 layout (std430, binding = 9) readonly buffer Data { DataS data[]; };
 layout (std140, binding = 0) uniform TheMat { mat4 theMat; } ;
 out vec2 texPos;
 out vec2 distmask;
+out vec2 pinch;
 const int ks[6] =   
     {0,1,2          //  2--3
     ,2,1,3          //  |  |
@@ -18,10 +19,28 @@ void main()
 {
   int k = ks[gl_VertexID];
   vec4 off = (theMat * vec4(data[gl_VertexID/6].pos, 0,1));
-  float r = distance
-        ((theMat * vec4(data[gl_VertexID/6].rad1, 0,1)).xy
-        ,(theMat * vec4(0,0, 0,1)).xy);
-  distmask = (cs[k] - off.xy)/r;
+  vec2 r1 = (theMat * vec4(data[gl_VertexID/6].v1, 0,1)).xy
+            - (theMat * vec4(0,0,0,1)).xy;
+  vec2 r2 = (theMat * vec4(data[gl_VertexID/6].v2, 0,1)).xy
+            - (theMat * vec4(0,0, 0,1)).xy;
+  pinch = 
+        (theMat * vec4(data[gl_VertexID/6].rad, 0,1)).xy
+        - (theMat * vec4(0,0, 0,1)).xy;
+//  mat2 distT = mat2(-1/r1.x, -1/r2.x
+//                   ,1/r1.y, -1/r2.y
+//                   );
+//  mat2 distT = mat2(2, 0
+//                   ,-1/sqrt(2), 1/sqrt(2)
+//                   );
+//  mat2 distT = mat2(1/r1.x, 2*sqrt(2)
+//                    ,1/r1.y, 2*sqrt(2)
+//                   );
+  mat2 distT = inverse (mat2(r1,r2));
+//  mat2 distT = mat2(1/r1.x, 1/r2.x
+//                   ,1/r1.y, 1/r2.y
+//                   );
+  //distmask = (cs[k] - off.xy)/r;
+  distmask = distT * (cs[k] - off.xy);
   texPos = 0.5 * (cs[k]+vec2(1,1));
   gl_Position = vec4 (cs[k],0,1);
 }