Deltographos::Blog

float i,j,d=.1,e; vec3 p;
for(i=0.;i++<64.&&d>1e-4;){
    p=vec3((FC.xy-.5*r)/r.y,1)*2.;
    p.z-=.5;
    for(j=0.;j++<4.;)
        p=abs(p)*rotate3D(i/j+t,vec3(p.x,p.z,p.y)),
        d=max(tan(length(p.xz)),sin(length(p.yz)))/d,
        d-=dot(p,-p)/4e4;
    e+=d;
}o+=vec4(sqrt(p),1)*3./i;