thebesfloat z=-9.;vec2 F=FC.xy/r.xy-.5;for(int i=0;i++<30;){float X=F.x*cos(t)-z*sin(t),Z=F.x*sin(t)+z*cos(t),h=sqrt(X*X+F.y*F.y)-.2,d=sqrt(h*h+Z*Z)-.05;if(d<.01){vec3 n=normalize(vec3(X*h,F.y*h,Z*(h+.2)));o=vec4(.95,.5,mix(.8,.3,sign(n.z+.3)),1.)*vec4(.3+max(0.,n.y));break;}z+=d;}
this is the same code as the donut sdf post (http://vgel.me/posts/donut) but ported to glsl and with the sampled normal replaced with an analytic one to save characters
twigl link: https://bit.ly/3IGn2sW