Several surf's combined with hold on/off - lighting issues

Alexander — Thu, 21 May 2009 21:17:01 -0400

Hello,

I am writing a program in which I create a 3D plot of an object consisting of several single parts. Here's an image:

http://img4.abload.de/img/spin_model0aa4.png

I am using surf. In order to plot the different objects, I plotted the first one with surf (keeping a handle), then plotted the other ones in the very same way, just with hold on/off. The result (like you see in the picture) is that something's wrong with the lighting. Even though I use phong shading and a "camlight left", the rings do not cast any shadows on the flat plate-like object.

How might I achieve that? Possibly by plotting all of the objects (rings and plate-like thing) into _one_ surf-command without doing the hold on/off process?

If yes: How can I plot all of the objects into one surf command? The plate is done with cylinder, the tori with a parametric plot? And even if I was able to put all of them into one surf plot somehow, I would require to keep track of where in those huge X, Y, Z matrices which object (ring etc.) is, because I need to rotate them.

If no: how then?

If you are interested in how exactly I do what with the hold on/off command, here's a commented minimal program (that acutally works):

Wait, let me say regards first:

Curious to read your responses!

Regards
Alexander

% --------------------minimal program-----------------

% Suppose I have tow simple objects, a sphere and a cylinder. They are to
% be plotted with surf

[X1,Y1,Z1]=cylinder;
[X2,Y2,Z2]=sphere;

% I can not plot them BOTH, at least I don't know how. So I plot one of
% them first, let's say the cylinder.

H=surf(X1,Y1,Z1);
axis square;

% Optional: I might do some shading stuff here, like in the image attatched above:

shading interp;
colormap copper;
FaceColor='copper';
EdgeColor='none';
camlight left;
lighting phong;

% Now I use hold on/off to add another surf plot

hold on;
G=surf (X2,Y2,Z2);
hold off;

% Now, both of them are contained in the current figure. I also kept their
% handles, so I can do with them whatever I need to do, I might for example
% rotate and translate them, scale them up etc.

% Here's just some translation

set(H,'XData',X1+1,'YData',Y1+1,'ZData',Z1+1);
set(G,'XData',X2+1,'YData',Y2+1,'ZData',Z2+1);
drawnow

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Several surf's combined with hold on/off - lighting issues