[orx-fx] Add fisheye distortion to Lenses Filter

orx-fx/src/shaders/glsl/distort/lenses.frag

@@ -2,25 +2,29 @@ in vec2 v_texCoord0;
 uniform sampler2D tex0;// input
 uniform float scale;
 uniform float rotation;
+uniform int rows;
+uniform int columns;
+uniform float distort;
 
 out vec4 o_color;
 void main() {
     vec2 uv = v_texCoord0;
-    vec2 blockSize = vec2(1.0/8.0, 1.0/6.0);
-
+    vec2 blockSize = vec2(1.0/columns, 1.0/rows);
     vec2 blockIndex = floor(uv / blockSize);
+    vec2 blockUV = mod(uv/blockSize, vec2(1.0));
+    vec2 blockUVC1 = (blockUV - vec2(0.5)) * 2.0;
     vec2 blockCenter = (blockIndex+0.5) * blockSize;
 
     float ca = cos(radians(rotation));
     float sa = sin(radians(rotation));
 
     vec2 ts = textureSize(tex0, 0);
-
-    mat2 rm =mat2(1.0, 0.0, 0.0, ts.x/ts.y) * mat2(vec2(ca, sa), vec2(-sa, ca)) * mat2(1.0, 0.0, 0.0, ts.y/ts.x);
-    vec2 cuv = (rm * (uv - blockCenter)
-    * scale + blockCenter);
-
-
+    mat2 rm = mat2(1.0, 0.0, 0.0, ts.x/ts.y) * mat2(vec2(ca, sa), vec2(-sa, ca)) * mat2(1.0, 0.0, 0.0, ts.y/ts.x);
+    vec2 ruv = (uv - blockCenter);
+    vec2 luv;
+    luv.x = (1.0 - blockUVC1.y * blockUVC1.y * distort) * ruv.x;
+    luv.y = (1.0 - blockUVC1.x * blockUVC1.x * distort) * ruv.y;
+    vec2 cuv = (rm * luv * scale + blockCenter);
 
     float sx = step(0.0, cuv.x) * (1.0 - step(1.0, cuv.x));
     float sy = step(0.0, cuv.y) * (1.0 - step(1.0, cuv.y));