import graph3;
import grid3;
import palette;

currentprojection=orthographic(0.8,1,2);
size(400,300,IgnoreAspect);

real f(pair z) {return cos(2*pi*z.x)*sin(2*pi*z.y);}

surface s=surface(f,(-1/2,-1/2),(1/2,1/2),50,Spline);

surface S=planeproject(unitsquare3)*s;
S.colors(palette(s.map(zpart),Rainbow()));
draw(S,nolight);
draw(s,lightgray+opacity(0.7));

grid3(XYZgrid);