curlesque.sksl

uniform float iTime;
uniform float2 iResolution;

// curlesque 
// Created by klk in 2018-04-11
// https://www.shadertoy.com/view/lsKyWV

// Created by Alex Kluchikov

const float pi = 3.14159265359;

float saw(float x)
{
    return abs(fract(x)-0.5)*2.0;
}

float dw(vec2 p, vec2 c, float t)
{
    return sin(length(p-c)-t);
}

float dw1(vec2 uv)
{
    float v=0.0;
    float t=iTime*2.0;
    v+=dw(uv,vec2(sin(t*0.07)*30.0,cos(t*0.04)*20.0),t*1.3);
    v+=dw(uv,vec2(cos(t*0.13)*30.0,sin(t*0.14)*20.0),t*1.6+1.0);
    v+=dw(uv,vec2( 18,-15),t*0.7+2.0);
    v+=dw(uv,vec2(-18, 15),t*1.1-1.0);
    return v/4.0;
}

float fun(float x, float y)
{
	return dw1(vec2(x-0.5,y-0.5)*80.0);
}

vec3 duv(vec2 uv)
{
    float x=uv.x;
    float y=uv.y;
    float v=fun(x,y);
    float d=1.0/400.0;
	float dx=(v-fun(x+d,y))/d;
	float dy=(v-fun(x,y+d))/d;
    float a=atan(dx,dy)/pi/2.0;
    return vec3(v,0,(v*4.0+a));
}

vec4 main( in vec2 fragCoord )
{
	  vec2 uv = fragCoord.xy/iResolution.x;
    vec3 h=duv(uv);
    float sp=saw(h.z+iTime*1.3);
    //sp=(sp>0.5)?0.3:1.0;
    sp=clamp((sp-0.25)*2.0,0.5,1.0);
    return vec4((h.x+0.5)*sp, (0.3+saw(h.x+0.5)*0.6)*sp, (0.6-h.x)*sp, 1.0);
}