Work on distortions

shader/texture/barrel.frag

@@ -4,20 +4,38 @@ in vec2 distmask;
 in vec2 pinch;
 out vec4 fColor;
 layout (binding = 1) uniform sampler2D screenTexture;
-float x = 1 - min(1, dot(distmask,distmask));
+float x = 1 - min(1, sqrt(distance(distmask,vec2(0,0))));
 float xab = abs(distmask.x);
 float yab = abs(distmask.y);
+vec3 toYUV (vec3 rgb)
+{ return rgb * mat3
+    ( 0.299  , 0.587  , 0.114
+    ,-0.14713,-0.28886, 0.436
+    , 0.615  ,-0.51499,-0.10001
+    ) ;
+}
+vec3 toRGB (vec3 yuv)
+{ return yuv * mat3
+    (1, 0      , 1.13983
+    ,1,-0.39465,-0.58060
+    ,1, 2.03211, 0
+    ) ;
+}
 void main()
 {
-    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
-    //    ) ;
+    fColor = texture(screenTexture, (texPos + x * pinch));
+    //fColor = texture(screenTexture, (texPos + x*pinch));
+    //fColor = texture(screenTexture, (texPos + x*pinch));
+//    fColor = vec4
+//        ( texture(screenTexture, (texPos + x*pinch)).r
+//        , texture(screenTexture, (texPos + x*(-pinch))).g
+//        , texture(screenTexture, texPos).ba
+//        ) ;
+//    fColor = vec4
+//        ( toRGB(vec3(  toYUV(texture(screenTexture, texPos).rgb).r
+//                , toYUV(texture(screenTexture, (texPos + x*pinch)).rgb).g
+//                , toYUV(texture(screenTexture, (texPos + x*(pinch))).rgb).b
+//                ) )
+//        , 1
+//        ) ;
 }

shader/texture/barrel.vert

@@ -1,5 +1,5 @@
 #version 450 core
-struct DataS { vec2 pos; vec2 v1; vec2 v2; vec2 rad; };
+struct DataS { vec2 pos; vec2 v1; vec2 v2; vec2 t1; vec2 t2; vec2 t3; };
 layout (std430, binding = 9) readonly buffer Data { DataS data[]; };
 layout (std140, binding = 0) uniform TheMat { mat4 theMat; } ;
 out vec2 texPos;
@@ -15,32 +15,41 @@ const vec2 cs[4] =
     , vec2 (-1, 1)
     , vec2 ( 1, 1)
     };
+vec2 f (vec2 p) // transforms a vector from "world" into "screen" space
+{ return (theMat * vec4(p,0,1) - theMat * vec4(0,0,0,1)).xy; }
+vec2 g (vec2 p)
+{ return normalize(p); }
+vec2 ncToTex (vec2 p) {return 0.5 * (p + 1);}
+mat4 toTransMat (vec2 p)
+{ return mat4
+    (  1,  0, 0 ,0
+    ,  0,  1, 0 ,0
+    ,  0,  0, 1 ,0
+    ,p.x,p.y, 0 ,1
+    ) ;
+}
 void main()
 {
   int k = ks[gl_VertexID];
-  vec4 off = (theMat * vec4(data[gl_VertexID/6].pos, 0,1));
-  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)
-//                   );
+  DataS thedata = data[gl_VertexID/6];
+  vec4 off = theMat * vec4(data[gl_VertexID/6].pos, 0,1);
+  vec2 r1 = f(thedata.v1);
+  vec2 r2 = f(thedata.v2);
   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));
+  vec4 pinchx = theMat 
+      * toTransMat(thedata.t3) 
+      * toTransMat(thedata.pos)
+      * mat4
+        (thedata.t1 , 0, 0
+        ,thedata.t2 , 0, 0
+        , 0,      0 , 0, 0
+        , 0,      0 , 0, 1
+        )
+      * inverse(toTransMat(thedata.pos))
+      * inverse(theMat) 
+      * (vec4(cs[k],0,1));
+  pinch = ncToTex(pinchx.xy) - ncToTex(cs[k]);
+  texPos = ncToTex(cs[k]);
   gl_Position = vec4 (cs[k],0,1);
 }