http://glsl.heroku.com/e#8443.0

burl2.glsl

#ifdef GL_ES
precision mediump float;
#endif

// burl figure


uniform vec2 resolution;
uniform float time;

const float Pi = 3.14159;

float sinApprox(float x) {
    x = Pi + (2.0 * Pi) * floor(x / (2.0 * Pi)) - x;
    return (4.0 / Pi) * x - (4.0 / Pi / Pi) * x * abs(x);
}

float cosApprox(float x) {
    return sinApprox(x + 0.5 * Pi);
}

void main()
{
  vec2 p=(2.0*gl_FragCoord.xy-resolution)/max(resolution.x,resolution.y);
	for(int i=1;i<50;i++)
	{
		vec2 newp=p;
		newp.x+=0.6/float(i)*sin(float(i)*p.y+time/20.0+0.3*float(i))+400./20.0;		
		newp.y+=0.6/float(i)*sin(float(i)*p.x+time/20.0+0.3*float(i+10))-400./20.0+15.0;
		p=newp;
	}
	vec3 col=vec3(0.5*sin(3.0*p.x)+0.5,0.5*sin(3.0*p.y)+0.5,sin(p.x+p.y));
	gl_FragColor=vec4(col, 1.0);
}