Dřevo
procedure wood(u,v,w: real; var r,g,b:real);
var radius, angle:real; grain: integer;
radius:=sqrt(sqr(u)+sqr(w));
if w=0 then angle:=pi/2 else angle:=arctan(u,w);
grain:=radius+2*sin(20*angle+v/150);
begin r:=r_light; g:=g_light; b:=b_light end
begin r:=r_dark; g:=g_dark; b:=b_dark; end;