Limit number of distortions to 10

shader/texture/barrel.frag

@@ -1,10 +1,11 @@
 #version 450 core
 in vec2 texPos;
-in vec2 distmask[2];
-in vec2 pinch[2];
+in vec2 distmask[10];
+in vec2 pinch[10];
 out vec4 fColor;
 layout (binding = 1) uniform sampler2D screenTexture;
-float x = 1 - min(1, sqrt(distance(distmask[0],vec2(0,0))));
+layout (location = 0) uniform int n;
+//float x = 1 - min(1, sqrt(distance(distmask[0],vec2(0,0))));
 //float x = 1 - min(1, dot(distmask,distmask));
 vec3 toYUV (vec3 rgb)
 { return rgb * mat3
@@ -22,11 +23,17 @@ vec3 toRGB (vec3 yuv)
 }
 void main()
 {
-    float y = 1 - min(1, sqrt(distance(distmask[1],vec2(0,0))));
-    fColor = texture(screenTexture
-            , (texPos + x * pinch[0] 
-                + y * pinch[1]
-                ));
+    vec2 tpos = texPos;
+    for(int i = 0; i < n; ++i)
+    {
+    float x = 1 - min(1, sqrt(distance(distmask[i],vec2(0,0))));
+    tpos += x * pinch[i];
+    }
+    fColor = texture(screenTexture, tpos);
+    //fColor = texture(screenTexture
+    //        , (texPos + x * pinch[0] 
+    //            + y * pinch[1]
+    //            ));
 }
 //    fColor = vec4
 //        ( toRGB(vec3(  toYUV(texture(screenTexture, texPos).rgb).r

shader/texture/barrel.vert

@@ -2,9 +2,10 @@
 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; } ;
+layout (location = 0) uniform int n;
 out vec2 texPos;
-out vec2 distmask[2];
-out vec2 pinch[2];
+out vec2 distmask[10];
+out vec2 pinch[10];
 const int ks[6] =   
     {0,1,2          //  2--3
     ,2,1,3          //  |  |
@@ -31,7 +32,7 @@ mat4 toTransMat (vec2 p)
 void main()
 {
   int k = ks[gl_VertexID];
-  for(int i = 0; i < 2; ++i)
+  for(int i = 0; i < n; ++i)
   {
   vec4 off = theMat * vec4(data[i + gl_VertexID/6].pos, 0,1);
   DataS thedata = data[i + gl_VertexID/6];