import graph3;
import palette;

size(8cm,0);
currentprojection=perspective(2,5,2);

real f(pair z) {return exp(-((z.x-1)^2+z.y^2))
                       -10*(z.x^3+z.x*z.y^4-z.x/5)*exp(-abs(z)^2);}

surface s=surface(f,(-3,-3),(3,3),60,60,Spline);

real[] level=uniform(-4.5,4.5,6);
s.colors(palette(s.map(new real(triple v) {return find(level >= v.z);}),
                 Rainbow())); 
draw(s,meshpen=blue);