private void OnLoaded(object sender, EventArgs e) { // setup trackball for moving the model around _trackball = new Trackball(); _trackball.Attach(this); _trackball.Servants.Add(myViewport3D); _trackball.Enabled = true; // Get the mesh objects for changing the material var mv3D = myViewport3D.Children[0] as ModelVisual3D; var m3DgBase = mv3D.Content as Model3DGroup; var m3Dg = m3DgBase.Children[0] as Model3DGroup; _topPlane = m3Dg.Children[2] as GeometryModel3D; _bottomPlane = m3Dg.Children[3] as GeometryModel3D; m3Dg = m3DgBase.Children[1] as Model3DGroup; _frontSpinPlane = m3Dg.Children[0] as GeometryModel3D; _backSpinPlane = m3Dg.Children[1] as GeometryModel3D; AnimateToNextPicture(); }