How do I get the position coordinates of a moving object?

I have four different 3d points in a single axes and have combined all the four points into a single object. Now I have defined their motion through the makehgtform command and then run it in a loop. The animation runs perfect. But at the end of every iteration, I would like to get the position coordinates data of the 3d points. Is it possible ? I am pasting the relevant code here as well.

if true
 rot = eye(4); % Rotation Matrix
 i = 1;
for r = 1:length(latitude)
   rot = makehgtform('zrotate',r);
  translation = makehgtform('translate', [latitude(i) longitude(i+1) altitude(i)]);
  set(combinedobj,'matrix',translation*rot);
  drawnow
  pause(0.3);
i = i+1;
end
end
%%The combinedobj in this code represents the 4 3d points combined into a single object. The value of the property "Matrix" changes every step and it is a 4 by 4 matrix (The value of translation*rot).Is it possible to get any information from this matrix?

Answer 1

[Walter Roberson]

m = get(combinedobj, 'matrix');

now multiply m by the original coordinates of the points as an N x 3 matrix. My mind is too foggy right now to remember how to deal with the translation.

[quicklearner]

Hi, Could you please explain what 'N' means ? I still do not get your logic. Kindly request you to explain a bit more. Thanks in Advance.

[Walter Roberson]

N would be 4 in your case. One row for each of your points.

See also http://blogs.mathworks.com/steve/2006/08/17/spatial-transformations-three-dimensional-rotation/