meh

experiments/rand/test1.frag

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+#ifdef GL_ES
+precision mediump float;
+#endif
+uniform vec2 u_resolution;
+uniform vec2 u_mouse;
+uniform float u_time;
+
+#define PI 3.14159265359
+
+const vec3 uAColor = vec3(.5,.5,.5);
+const vec3 uBColor = vec3(.5,.5,.5);
+const vec3 uCColor = vec3(1.,1.,1.);
+const vec3 uDColor = vec3(.0,.33,.67);
+
+//get colors from http://dev.thi.ng/gradients/
+vec3 cosPalette(float t) { return uAColor + uBColor*cos(6.28318*(uCColor*t+uDColor)); }
+
+
+float rand(vec2 st) { 
+  return fract(sin(dot(st, vec2(323.*sin(u_time), 3.*cos(u_time+u_time/3.))))/cos(2.*u_time));
+}
+
+float fill(float x, float size) { return 1.-step(size, x); }
+
+float circleSDF(vec2 st) { return length(st); }
+
+void main() {
+  vec2 st = (gl_FragCoord.xy*2. - u_resolution.xy)/u_resolution.y;
+  vec2 stm = (u_mouse*2. - u_resolution.xy)/u_resolution.y;
+  float rng = rand(fract(st * 10999.));
+  vec3 color = vec3(0.0,0.0,0.0);
+  float alpha = 1.0;
+  float c = circleSDF(st-stm);
+  color += cosPalette(fill(c, .2)*rng+rng*.05);
+
+  
+
+
+
+  gl_FragColor = vec4(color, alpha);
+}