with(plots):
D2mapD2 := proc(lin1, lin2, plotpoints)
	# lin1 is a*s+b*t+c, s=0..1, t=0..1, is the height
	# lin2 is aa*s+bb*t+cc, s=0..1, t=0..1, is the color
	local plot;
	plot := seq(
                 seq(
                  polygonplot3d([subs({s=1/plotpoints*i, t=1/plotpoints*j},
		 	   	   [s,t,lin1]),
				 subs({s=1/plotpoints*(i+1), t=1/plotpoints*j},
                                   [s,t,lin1]),
                                 subs({s=1/plotpoints*(i+1), t=1/plotpoints*(j+1)},
                                   [s,t,lin1]),
                                 subs({s=1/plotpoints*i, t=1/plotpoints*(j+1)},
                                   [s,t,lin1])],
				color = COLOR(HUE,
					      subs({s=1/plotpoints*i, t=1/plotpoints*j},
                                                   lin2))
			       ),
		     i=0..plotpoints-1),
	            j=0..plotpoints-1);
	display([plot]);
end;