weird: added another iteration of ikeda games; utils: added a perlin noise-like noise function

utilities/random.glsl

@@ -3,3 +3,9 @@ float random(vec2 st) {
                          vec2(12.9898,78.233)))*
         43758.5453123);
 }
+
+float noise(float x) {
+  float i = floor(x);
+  float f = fract(x);
+  return mix(rand(i), rand(i + 1.0), smoothstep(0.,1.,f));
+}

weird/ikeda3.glsl

@@ -0,0 +1,40 @@
+#ifdef GL_ES
+precision mediump float;
+#endif
+
+uniform vec2 u_resolution;
+uniform float u_time;
+uniform vec2 u_mouse;
+
+float random(in float x) {
+    return fract(sin(x)*1e6);
+}
+
+float randcol(float x, float f, float t) {
+    return step(0.75,random(floor(x*f)-floor(t)));
+}
+
+void main() {
+    vec2 st = gl_FragCoord.xy/u_resolution.xy;
+    st.x *= u_resolution.x/u_resolution.y;
+
+    float cols = 64.;
+    float freq = random(floor(u_time))+abs(atan(u_time)*.1);
+    float t = 40.*u_time*(1.-freq);
+
+    if (gl_FragCoord.y < u_mouse.y && st.y < 0.9) {
+        gl_FragColor = vec4(1.);
+        return;
+    }
+
+    if (fract(st.y*cols*.5) < .5) t *= -1.;
+
+    freq += random(floor(st.y*20.));
+
+    float offset = .025;
+    vec3 color = vec3(randcol(st.x, freq*100.+random(freq), t+offset),
+                      randcol(st.x, freq*100., t),
+                      randcol(st.x, freq*100.+random(freq), t-offset));
+
+    gl_FragColor = vec4(1.-color,1.);
+}