From 1cd805625919a950dd880fb9ab4ece50b31016da Mon Sep 17 00:00:00 2001
From: hellerve <veit@veitheller.de>
Date: Mon, 12 Jun 2017 18:52:32 -0400
Subject: [PATCH] weird: added flow noise

---
 weird/flow_noise.glsl | 86 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 86 insertions(+)
 create mode 100644 weird/flow_noise.glsl

diff --git a/weird/flow_noise.glsl b/weird/flow_noise.glsl
new file mode 100644
index 0000000..c41b8eb
--- /dev/null
+++ b/weird/flow_noise.glsl
@@ -0,0 +1,86 @@
+#ifdef GL_ES
+precision mediump float;
+#endif
+
+#define NUM_OCTAVES 5
+#define TAU 6.28318530718
+
+uniform vec2 u_resolution;
+uniform float u_time;
+
+float random (vec2 _st) {
+    return fract(sin(dot(_st.xy, vec2(12.9898,78.233)))*43758.5453123);
+}
+
+float noise (vec2 _st) {
+    vec2 i = floor(_st);
+    vec2 f = fract(_st);
+
+    float a = random(i);
+    float b = random(i + vec2(1.0, 0.0));
+    float c = random(i + vec2(0.0, 1.0));
+    float d = random(i + vec2(1.0, 1.0));
+
+    vec2 u = f * f * (3.0 - 2.0 * f);
+
+    return mix(a, b, u.x) +
+            (c - a)* u.y * (1.0 - u.x) +
+            (d - b) * u.x * u.y;
+}
+
+float fbm(vec2 _st) {
+    float v = 0.0;
+    float a = 0.5;
+    vec2 shift = vec2(100.0);
+    mat2 rot = mat2(cos(0.5), sin(0.5),
+                    -sin(0.5), cos(0.50));
+    for (int i = 0; i < NUM_OCTAVES; ++i) {
+        v += a * noise(_st);
+        _st = rot * _st * 2.0 + shift;
+        a *= 0.5;
+    }
+    return v;
+}
+
+vec3 polygon(int n, float size, vec2 pos, vec3 color, float rot) {
+  float e = 0.01;
+  vec2 st = gl_FragCoord.xy/u_resolution.xy;
+  st.x *= u_resolution.x/u_resolution.y;
+  st = (st-pos)*2.;
+  float a = atan(st.x,st.y)+rot;
+  float r = TAU/float(n);
+
+  float d = cos(floor(.5+a/r)*r-a)*length(st);
+
+  return color-smoothstep(size-e,size+e,d);
+}
+
+vec3 _m(vec3 c1, vec3 c2, float v) {
+    return mix(c1, c2, clamp(v, 0., 1.));
+}
+
+void main() {
+    vec2 st = gl_FragCoord.xy/u_resolution.xy*3.;
+    vec3 color = vec3(0.0);
+
+    float _f = fbm(st+u_time*0.2);
+    vec2 q = vec2(_f);
+
+    _f = fbm(st+1.*q);
+    vec2 r = vec2(_f);
+
+    float f = fbm(st+r);
+
+    color = _m(vec3(0.1,0.62,0.67),vec3(0.67,0.67,0.5), f);
+
+    color = mix(color, vec3(0,0,0.16), length(q));
+
+    color = mix(color, vec3(0.67,1,1), length(r.x));
+
+
+    float resmin = min(u_resolution.x, u_resolution.y);
+    vec2 size = (u_resolution/2.)/resmin;
+    color += polygon(4, 0.7, size, -vec3(0.3), 0.8);
+
+    gl_FragColor = vec4(color,1.);
+}