Lighting Stays with Animated Surface in Matlab

Question

I'm attempting to animate a rotating sphere in Matlab, however the lighting on the sphere rotates with it. I instead want the sphere to rotate while the lighting remains fixed with the coordinate system. Here's a gif of what my code is currently producing: Animation. And here is my code:

% Simulation Time
dt = 0.05;
time = 0:dt:5;

% Prep Figure
figure('Color',[1 1 1],'Renderer','zbuffer','ColorMap', [1,0,0; 0,0,1])

% Generate Sphere
[X,Y,Z] = sphere(20);
r = 0.75*25.4;
h = surf(r*X,r*Y,r*Z,Z,'FaceColor','interp');
hold on

% Adjust Axes, Lighting, and Shading
axis equal
view([40 25]);
light('Position',[1 1 1])
set(findobj(gca,'type','surface'),...
            'FaceLighting','phong',...
            'AmbientStrength',.3,'DiffuseStrength',.8,...
            'SpecularStrength',.9,'SpecularExponent',25,...
            'BackFaceLighting','unlit','EdgeColor','k')

filename = 'Rotation.gif';
for n = 1:36

      rotate(h,[0 0 1],10,[0 0 0])
      im = frame2im(getframe(1));
      [imind,cm] = rgb2ind(im,256);

      if n == 1;
          imwrite(imind,cm,filename,'gif', 'Loopcount',inf,'DelayTime',dt);
      else
          imwrite(imind,cm,filename,'gif','WriteMode','append','DelayTime',dt);
      end

end

Answer 1

As already mentioned in the comments:

Seems like it might be an issue with the surface VertexNormals not updating.

The solution was to download the rotate.m function fixed File Exchange submission.

The description:

Bug evidence:

[x,y,z] = sphere(20); 
hs=surf(x,y,z,'facecolor','y'); 
view(2) 
axis equal 
hl=light; 
lightangle(hl,0,0) 
% light is on -Y axis, thus at the 
% bottom 
rotate(hs,[0 0 1],30) 
% rotate sphere to the right from 30°

It looks like the light has moved. This is due to a bug in rotate.m function. The "VertexNormals" property of the surf object is not updated as "xdata", "ydata" and "zdata" properties are.

This is fixed in the submitted version of rotate.m.