weird: added i ching example

weird/i_ching.glsl

@@ -0,0 +1,74 @@
+#ifdef GL_ES
+precision mediump float;
+#endif
+
+#define PI 3.14159265359
+#define TWO_PI 6.28318530718
+
+uniform vec2 u_resolution;
+uniform float u_time;
+
+float shape(vec2 st, float n) {
+    st = st*2.-1.;
+    float a = atan(st.x,st.y)+PI;
+    float r = TWO_PI/n;
+    return abs(cos(floor(.5+a/r)*r-a)*length(st));
+}
+
+float box(vec2 st, vec2 size) {
+    return shape(st*size, 4.);
+}
+
+float rect(vec2 _st, vec2 _size) {
+    _size = vec2(0.5)-_size*0.5;
+    vec2 uv = smoothstep(_size,_size+vec2(1e-4),_st);
+    uv *= smoothstep(_size,_size+vec2(1e-4),vec2(1.0)-_st);
+    return uv.x*uv.y;
+}
+
+float _mix(vec2 pos, float x) {
+    return mix(box(pos, vec2(0.84,1.)),box(pos-vec2(0.03,0.),vec2(1.)), x);
+}
+
+float hex(vec2 st, float a, float b, float c, float d, float e, float f){
+    st = st*vec2(2.,6.);
+
+    vec2 fpos = fract(st);
+    vec2 ipos = floor(st);
+
+    if (ipos.x == 1.0) fpos.x = 1.-fpos.x;
+
+    if (ipos.y < 1.0) return _mix(fpos ,a);
+    else if (ipos.y < 2.0) return _mix(fpos, b);
+    else if (ipos.y < 3.0) return _mix(fpos, c);
+    else if (ipos.y < 4.0) return _mix(fpos, d);
+    else if (ipos.y < 5.0) return _mix(fpos, e);
+    else if (ipos.y < 6.0) return _mix(fpos, f);
+    return 0.0;
+}
+
+float hex(vec2 st, float n) {
+    float b[6];
+    float remain = floor(mod(n,64.));
+    for(int i = 0; i < 6; i++){
+        b[i] = 0.0;
+        b[i] = step(1.0,mod(remain,2.));
+        remain = ceil(remain/2.);
+    }
+    return hex(st,b[0],b[1],b[2],b[3],b[4],b[5]);
+}
+
+void main(){
+    vec2 st = gl_FragCoord.xy/u_resolution.xy;
+    st.y *= u_resolution.y/u_resolution.x;
+
+    st *= 10.0;
+    vec2 fpos = fract(st);
+    vec2 ipos = floor(st);
+
+    float t = u_time*10.0;
+    float df = 1.0;
+    df = hex(fpos,ipos.x+ipos.y+t)+(1.0-rect(fpos,vec2(0.7)));
+
+    gl_FragColor = vec4(mix(vec3(0.17),vec3(238./255., 220./255., 190./255.),step(0.7,df)),1.0);
+}