ok, kben er

learning/patterns/rotates.frag

@@ -0,0 +1,59 @@
+#ifdef GL_ES
+precision mediump float;
+#endif
+uniform vec2 u_resolution;
+uniform vec2 u_mouse;
+uniform float u_time;
+
+#define PI 3.14159265359
+
+vec2 rotate2D (vec2 st, float angle) {
+  st -= .5;
+  st = mat2(cos(angle),-sin(angle),
+            sin(angle),cos(angle))*st;
+  st += .5;
+  return st;
+
+}
+
+vec2 tile (vec2 st, float zoom) {
+  st *= zoom;
+  return fract(st);
+}
+
+vec2 rotateTilePatter(vec2 st) {
+  st *= 2.;
+  float index = 0.0;
+  index += step(1., mod(st.x,2.));
+  index += step(1.,mod(st.y,2.))*2.;
+  st = fract(st);
+
+  if(index == 1.) {
+    st = rotate2D(st, PI*.5);
+  } else if (index == 2.){
+    st = rotate2D(st, PI*-.5);
+  } else if (index == 3.){
+    st = rotate2D(st, PI);
+  }
+
+  return st;
+}
+
+
+void main() {
+  vec2 st = (gl_FragCoord.xy*2. - u_resolution.xy)/u_resolution.y;
+//  vec2 st = gl_FragCoord.xy/u_resolution.xy;
+
+  vec3 color = vec3(0.0,0.0,0.0);
+  float alpha = 1.0;
+  st = fract(st*2.);
+  st = rotateTilePatter(st);
+  
+  color += step(st.x,st.y);
+
+
+
+  
+
+  gl_FragColor = vec4(color, alpha);
+}