float i,d=1.,g,q;vec3 Z;for(;i++<75.&&d>1e-4;g+=d,Z=normalize(vec3(FC.xy-r*.5,r.y*.5))*g,Z.z+=t*.2)for(q=1.;q++<4.;Z=(abs(abs(fract(Z*q)-.5)-.05)-.1*sin(Z.z))/q,Z.xz*=rotate2D(Z.y*q),d=min(d,min(max(Z.x,Z.y),min(max(Z.y,Z.z),max(Z.z,Z.x)))),o.rgb=exp(-4.*fract(t+Z.xzz+g))*40./i);
