Re: Problema figure 3D asymptote

Codice latex e la figura asymptote di seguito:“
\documentclass[a4paper,11pt]{article}
\usepackage[latin1]{inputenc}
\usepackage{lmodern}
\usepackage[T1]{fontenc}
\usepackage[italian]{babel}
\usepackage{graphicx}
\usepackage{xcolor}
\usepackage{booktabs}
\graphicspath{{Figure/}}
\begin{document}
Ciao.
\begin{figure}[hbtp]
\centering
\includegraphics[width=0.7\columnwidth,height=0.3\textheight]{prova}
\caption{Surface}
\label{fig:6}
\end{figure}
\end{document}

size(12cm,0,false);
import graph3;
currentprojection=perspective(3.2,-3,1.25);
real f(pair z) {return 1/(2(z.x-2)^2+2z.y^2+1)+1/(2z.x^2+2z.y^2+1)-2/(2(z.x-1)^2+2(z.y+1)^2+1);}
draw(surface(f,(-0.5,-3),(2.5,3.5),50,Spline),palegrey+opacity(0.1),meshpen=black);
scale(true);