thebookofshaders/11/iching-03.frag

// Author @patriciogv ( patriciogonzalezvivo.com ) - 2015

#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, int N){
    st = st*2.-1.;
    float a = atan(st.x,st.y)+PI;
    float r = TWO_PI/float(N);
    return cos(floor(.5+a/r)*r-a)*length(st);
}

float box(vec2 st, vec2 size){
    return shape(st*size,4);
}

float hex(vec2 st, bool a, bool b, bool c, bool d, bool e, bool 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 a? box(fpos-vec2(0.03,0.), vec2(1.)) : box(fpos, vec2(0.84,1.));
    } else if (ipos.y < 2.0){
        return b? box(fpos-vec2(0.03,0.), vec2(1.)) : box(fpos, vec2(0.84,1.));
    } else if (ipos.y < 3.0){
        return c? box(fpos-vec2(0.03,0.), vec2(1.)) : box(fpos, vec2(0.84,1.));
    } else if (ipos.y < 4.0){
        return d? box(fpos-vec2(0.03,0.), vec2(1.)) : box(fpos, vec2(0.84,1.));
    } else if (ipos.y < 5.0){
        return e? box(fpos-vec2(0.03,0.), vec2(1.)) : box(fpos, vec2(0.84,1.));
    } else if (ipos.y < 6.0){
        return f? box(fpos-vec2(0.03,0.), vec2(1.)) : box(fpos, vec2(0.84,1.));
    }
    return 0.0;
}

float hex(vec2 st, float N){
    bool b[6];
    float remain = floor(mod(N,64.));
    for(int i = 0; i < 6; i++){
        b[i] = mod(remain,2.)==1.?true:false;
        remain = ceil(remain/2.);
    }
    return hex(st,b[0],b[1],b[2],b[3],b[4],b[5]);
}

vec3 random3(vec3 c) {
    float j = 4096.0*sin(dot(c,vec3(17.0, 59.4, 15.0)));
    vec3 r;
    r.z = fract(512.0*j);
    j *= .125;
    r.x = fract(512.0*j);
    j *= .125;
    r.y = fract(512.0*j);
    return r-0.5;
}

const float F3 =  0.3333333;
const float G3 =  0.1666667;
float snoise(vec3 p) {

    vec3 s = floor(p + dot(p, vec3(F3)));
    vec3 x = p - s + dot(s, vec3(G3));

    vec3 e = step(vec3(0.0), x - x.yzx);
    vec3 i1 = e*(1.0 - e.zxy);
    vec3 i2 = 1.0 - e.zxy*(1.0 - e);

    vec3 x1 = x - i1 + G3;
    vec3 x2 = x - i2 + 2.0*G3;
    vec3 x3 = x - 1.0 + 3.0*G3;

    vec4 w, d;

    w.x = dot(x, x);
    w.y = dot(x1, x1);
    w.z = dot(x2, x2);
    w.w = dot(x3, x3);

    w = max(0.6 - w, 0.0);

    d.x = dot(random3(s), x);
    d.y = dot(random3(s + i1), x1);
    d.z = dot(random3(s + i2), x2);
    d.w = dot(random3(s + 1.0), x3);

    w *= w;
    w *= w;
    d *= w;

    return dot(d, vec4(52.0));
}

void main(){
	vec2 st = gl_FragCoord.xy/u_resolution.xy;
    st.y *= u_resolution.y/u_resolution.x;

    float t = u_time*0.5;

    float df = 1.0;
    df = mix(hex(st,t),hex(st,t+1.),fract(t));
    df += snoise(vec3(st*75.,t*0.1))*0.03;
	gl_FragColor = vec4(mix(vec3(0.),vec3(1.),step(0.7,df)),1.0);
}