title: Disable face culling in WPF
body: <p>I'm starting experimenting with WPF 3D rendering, and one of the first problems I'm facing, is how to disable face culling.
  I know how to do that in DirectX and OpenGL, but I can't find a way to do that in WPF.
  Here is my ViewPort markup. The model is generated at runtime, and it's a MeshGeometry3D inside a GeometryModel3D</p>
  
  <pre><code>  &lt;Viewport3D x:Name="viewport"  DockPanel.Dock="Right" Margin="0" &gt;
                  &lt;Viewport3D.Camera&gt;
                      &lt;PerspectiveCamera x:Name="camera" FarPlaneDistance="50" LookDirection="0,0,-10"
       UpDirection="0,1,0" NearPlaneDistance="0" Position="0,0,5"
       FieldOfView="45" /&gt;
                  &lt;/Viewport3D.Camera&gt;
  
                  &lt;ModelVisual3D x:Name="model"&gt;
                      &lt;ModelVisual3D.Content&gt;
                          &lt;Model3DGroup x:Name="group"&gt;
                              &lt;AmbientLight Color="DarkGray" /&gt;
                              &lt;DirectionalLight Color="White" Direction="-5,-5,-7" /&gt;
                          &lt;/Model3DGroup&gt;
                      &lt;/ModelVisual3D.Content&gt;
                  &lt;/ModelVisual3D&gt;
              &lt;/Viewport3D&gt;
  </code></pre>
  
  <p>Thanks very much for any suggestion you could give me.</p>