Clarify number of distortions, play with distorting bullets

shader/texture/barrel.frag

@@ -1,9 +1,10 @@
 #version 450 core
 in vec2 texPos;
-in vec2 distmask[10];
-in vec2 pinchr[10];
-in vec2 pinchg[10];
-in vec2 pinchb[10];
+const int n1 = 15;
+in vec2 distmask[n1];
+in vec2 pinchr[n1];
+in vec2 pinchg[n1];
+in vec2 pinchb[n1];
 out vec4 fColor;
 layout (binding = 1) uniform sampler2D screenTexture;
 layout (location = 0) uniform int n;
@@ -34,8 +35,8 @@ void main()
     tposb += x * pinchb[i];
     }
     fColor.r = texture(screenTexture, tposr).r;
-    fColor.b = texture(screenTexture, tposb).b;
     fColor.g = texture(screenTexture, tposg).g;
+    fColor.b = texture(screenTexture, tposb).b;
 }
 //    fColor = vec4
 //        ( toRGB(vec3(  toYUV(texture(screenTexture, texPos).rgb).r

shader/texture/barrel.vert

@@ -7,11 +7,17 @@ struct DataS { vec2 pos; vec2 v1; vec2 v2;
 layout (std430, binding = 9) readonly buffer Data { DataS data[]; };
 layout (std140, binding = 0) uniform TheMat { mat4 theMat; } ;
 layout (location = 0) uniform int n;
+// setting n1 > 15 does not work on my current hardware
+// on other hardware n = 15 might not work
+// e.g. if GL_MAX_VERTEX_OUTPUT_COMPONENTS < 128
+// note the vec2s might be treated as vec4s
+// note also the limit on GL_MAX_VARYING_COMPONENTS
+const int n1 = 15;
 out vec2 texPos;
-out vec2 distmask[10];
-out vec2 pinchr[10];
-out vec2 pinchg[10];
-out vec2 pinchb[10];
+out vec2 distmask[n1];
+out vec2 pinchr[n1];
+out vec2 pinchg[n1];
+out vec2 pinchb[n1];
 const int ks[6] =   
     {0,1,2          //  2--3
     ,2,1,3          //  |  |
@@ -24,9 +30,8 @@ const vec2 cs[4] =
     };
 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);}
+// don't need mat4 here, could get away with mat3...
 mat4 toTransMat (vec2 p)
 { return mat4
     (  1,  0, 0 ,0
@@ -40,51 +45,51 @@ void main()
   int k = ks[gl_VertexID];
   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];
-  vec2 r1 = f(thedata.v1);
-  vec2 r2 = f(thedata.v2);
-  mat2 distT = inverse (mat2(r1,r2));
-  distmask[i] = (distT * (cs[k] - off.xy));
-  vec4 pinchxr = theMat 
-      * toTransMat(thedata.t3r) 
-      * toTransMat(thedata.pos)
-      * mat4
-        (thedata.t1r , 0, 0
-        ,thedata.t2r , 0, 0
-        , 0,      0 , 0, 0
-        , 0,      0 , 0, 1
-        )
-      * inverse(toTransMat(thedata.pos))
-      * inverse(theMat) 
-      * (vec4(cs[k],0,1));
-  pinchr[i] = ncToTex(pinchxr.xy) - ncToTex(cs[k]);
-  vec4 pinchxg = theMat 
-      * toTransMat(thedata.t3g) 
-      * toTransMat(thedata.pos)
-      * mat4
-        (thedata.t1g , 0, 0
-        ,thedata.t2g , 0, 0
-        , 0,      0 , 0, 0
-        , 0,      0 , 0, 1
-        )
-      * inverse(toTransMat(thedata.pos))
-      * inverse(theMat) 
-      * (vec4(cs[k],0,1));
-  pinchg[i] = ncToTex(pinchxg.xy) - ncToTex(cs[k]);
-  vec4 pinchxb = theMat 
-      * toTransMat(thedata.t3b) 
-      * toTransMat(thedata.pos)
-      * mat4
-        (thedata.t1b , 0, 0
-        ,thedata.t2b , 0, 0
-        , 0,      0 , 0, 0
-        , 0,      0 , 0, 1
-        )
-      * inverse(toTransMat(thedata.pos))
-      * inverse(theMat) 
-      * (vec4(cs[k],0,1));
-  pinchb[i] = ncToTex(pinchxb.xy) - ncToTex(cs[k]);
+    DataS thedata = data[i + gl_VertexID/6];
+    vec4 off = theMat * vec4(thedata.pos, 0,1);
+    vec2 r1 = f(thedata.v1);
+    vec2 r2 = f(thedata.v2);
+    mat2 distT = inverse (mat2(r1,r2));
+    distmask[i] = (distT * (cs[k] - off.xy));
+    vec4 pinchxr = theMat 
+        * toTransMat(thedata.t3r) 
+        * toTransMat(thedata.pos)
+        * mat4
+          (thedata.t1r , 0, 0
+          ,thedata.t2r , 0, 0
+          , 0,      0 , 0, 0
+          , 0,      0 , 0, 1
+          )
+        * inverse(toTransMat(thedata.pos))
+        * inverse(theMat) 
+        * (vec4(cs[k],0,1));
+    pinchr[i] = ncToTex(pinchxr.xy) - ncToTex(cs[k]);
+    vec4 pinchxg = theMat 
+        * toTransMat(thedata.t3g) 
+        * toTransMat(thedata.pos)
+        * mat4
+          (thedata.t1g , 0, 0
+          ,thedata.t2g , 0, 0
+          , 0,      0 , 0, 0
+          , 0,      0 , 0, 1
+          )
+        * inverse(toTransMat(thedata.pos))
+        * inverse(theMat) 
+        * (vec4(cs[k],0,1));
+    pinchg[i] = ncToTex(pinchxg.xy) - ncToTex(cs[k]);
+    vec4 pinchxb = theMat 
+        * toTransMat(thedata.t3b) 
+        * toTransMat(thedata.pos)
+        * mat4
+          (thedata.t1b , 0, 0
+          ,thedata.t2b , 0, 0
+          , 0,      0 , 0, 0
+          , 0,      0 , 0, 1
+          )
+        * inverse(toTransMat(thedata.pos))
+        * inverse(theMat) 
+        * (vec4(cs[k],0,1));
+    pinchb[i] = ncToTex(pinchxb.xy) - ncToTex(cs[k]);
   }
   texPos = ncToTex(cs[k]);
   gl_Position = vec4 (cs[k],0,1);