Lighting Stays with Surface in Animation

Question

Josh 2014-7-11

1
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/141356-lighting-stays-with-surface-in-animation

编辑： Josh 2014-7-11

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

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Answer 1

Josh 2014-7-11

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/141356-lighting-stays-with-surface-in-animation#answer_144687

编辑：Josh 2014-7-11

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