title: Multiple viewport with same model in wpf
body: <p>I referenced from this <a href="https://stackoverflow.com/questions/16191985/rendering-the-same-model-in-multiple-wpf-viewports">Rendering the same model in multiple WPF Viewports
  </a></p>
  
  <p>I'm a wpf beginner and have the similar question with that link. I want to show three models which would move relatively and show in different viewport with different camera setting.</p>
  
  <p>At first I tried to add ModelVisual3D to different viewport, and it didn't work obviously.</p>
  
  <p>So I tried to do this below, here is the code:</p>
  
  <pre><code>Model3DGroup model1 = read(path1);
  Model3DGroup model2 = read(path2);
  Model3DGroup model3 = read(path3);
  
  modelVisual1.Content = model1 ;
  modelVisual2.Content = model2 ;
  modelVisual3.Content = model3 ;
  
  mainModelVisual.Children.Add(modelVisual1);
  mainModelVisual.Children.Add(modelVisual2);
  mainModelVisual.Children.Add(modelVisual3);
  
  Viewport1.Children.Add(mainModelVisual);
  </code></pre>
  
  <p>The reason why I don't use just one Model3DGroup is that I have assign different 
  <code>Transform3D</code> and I will add the hittest in future.(Is that a appropriate reason?)</p>
  
  <p>And now I want to add the model to different viewport like this:</p>
  
  <pre><code>otherMainModelVisual2.Content = mainModelVisual.Content;
  otherMainModelVisual3.Content = mainModelVisual.Content;
  
  Viewport2.Children.Add(otherMainModelVisual2);
  Viewport3.Children.Add(otherMainModelVisual3);
  </code></pre>
  
  <p>The <strong>viewport1</strong> will show the model normally, but other viewport didn't show anything.</p>
  
  <p>The question is why I can't do this like the link?
  Or do I have to copy two models and add to different modelvisual like the <strong>viewport1</strong>?</p>
  
  <p>I'm a beginner, hope anyone could show me in simple code.</p>