void main()
{
	for(
	vec3 r = vec3(u_resolution, 1),
	d = (vec3(gl_FragCoord.xy*2., 0)-r)/r.xxz,
	p = 90./r,
	q;
    
	r.z++<2e2;
	q = p += d*length(min(10.-abs(q),.2))-d)
    
        	q.xz *= mat2(cos(u_time + vec4(0,11,23,0))),
        
        gl_FragColor = vec4(7./r.x / fwidth(q), p.z*.3+9.);
}
//created by firstuser at shadergrounds.com