Lighting Stays with Surface in Animation

I'm attempting to animate a rotating sphere, however the lighting on the sphere rotates with it in certain situations. I instead want the the lighting to remain fixed with the coordinate system while the sphere rotates. Here's a gif of what my code is currently producing: Animation . Below is the code I used to produce the animation. The weird thing is this only happens with rotations about the z-axis. As can be seen in the animation, the lighting works fine for x-axis rotation.

% 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 off
axis equal
view([40 25]);

lgt = 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

    for n = 1:36

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

    imwrite(imind,cm,filename,'gif','WriteMode','append','DelayTime',dt);

    end

Answer 1

[Josh]

I've found a solution to this problem thanks to the folks over at stackoverflow. The issue is caused by the surface VertexNormals not updating properly in the rotation function. This updated rotation function solves the issue:

http://www.mathworks.co.uk/matlabcentral/fileexchange/35210-rotate-m-function-fixed