import graph3; import palette; import contour3; size(400); real f(real x, real y, real z) { return cos(x)*sin(y)+cos(y)*sin(z)+cos(z)*sin(x); } surface sf=surface(contour3(f,(-2pi,-2pi,-2pi),(2pi,2pi,2pi),12)); sf.colors(palette(sf.map(abs),Gradient(red,yellow))); draw(sf,nolight);