%利用“非數”NaN，對圖形進行剪切處理
t=linspace(0,2*pi,100);r=1-exp(-t/2).*cos(4*t);
[X,Y,Z]=cylinder(r,60);
ii=find(X<0&Y<0);
Z(ii)=NaN;
surf(X,Y,Z);colormap(spring),shading interp
light('position',[-3,-1,3],'style','local')
material([0.5,0.4,0.3,10,0.3])
%透視演示
[X0,Y0,Z0]=sphere(30);
X=2*X0;Y=2*Y0;Z=2*Z0;
surf(X0,Y0,Z0);
shading interp
hold on,mesh(X,Y,Z),colormap(hot),hold off
hidden off
axis equal,axis off
%利用“非數”NaN，對圖形進行鏤空處理
P=peaks(30);P(18:20,9:15)=NaN;
surfc(P);colormap(summer)
light('position',[50,-10,5]),lighting flat
material([0.9,0.9,0.6,15,0.4])
%表現切面
clf,x=[-8:0.2:8];y=x;[X,Y]=meshgrid(x,y);ZZ=X.^2-Y.^2;
ii=find(abs(X)>6|abs(Y)>6);
ZZ(ii)=zeros(size(ii));
surf(X,Y,ZZ),shading interp;colormap(copper)
light('position',[0,-15,1]);lighting phong
material([0.8,0.8,0.5,10,0.5])