<Grid MouseDown="Grid_MouseDown">    <Viewport3D>        <Viewport3D.Camera>            <!-- Position属性指定3D空间中摄像机的位置，LookDirection属性为摄像机方向 -->            <PerspectiveCamera Position="0 0 500" LookDirection="0 0 -1" />        </Viewport3D.Camera>        <Viewport3D.Children>            <ContainerUIElement3D>                <Viewport2DVisual3D>                    <Viewport2DVisual3D.Geometry>                        <!-- Positions属性表示绘制对象的点集合，TriangleIndices属性表示对象的正反面（WPF通过逆时针环绕表示正面），TextureCoordinates属性表示2D纹理映射到3D对象 -->                        <!-- 一般通过3D建模工具推导得出 -->                        <MeshGeometry3D Positions="-200 200 0  -200 -200 0  200 -200 0  200 200 0" TriangleIndices="0 1 2  0 2 3" TextureCoordinates="0 0  0 1  1 1  1 0"/>                    </Viewport2DVisual3D.Geometry>                    <Viewport2DVisual3D.Material>                        <DiffuseMaterial Viewport2DVisual3D.IsVisualHostMaterial="True"/>                    </Viewport2DVisual3D.Material>                    <Viewport2DVisual3D.Visual>                        <!-- 放置正面自定义用户控件 -->                        <Page:Win1 Width="400" Height="400"/>                    </Viewport2DVisual3D.Visual>                </Viewport2DVisual3D>                <Viewport2DVisual3D>                    <Viewport2DVisual3D.Geometry>                        <MeshGeometry3D Positions="200 200 0  200 -200 0  -200 -200 0  -200 200 0" TriangleIndices="0 1 2  0 2 3" TextureCoordinates="0 0  0 1  1 1  1 0"/>                    </Viewport2DVisual3D.Geometry>                    <Viewport2DVisual3D.Material>                        <DiffuseMaterial Viewport2DVisual3D.IsVisualHostMaterial="True"/>                    </Viewport2DVisual3D.Material>                    <Viewport2DVisual3D.Visual>                        <!-- 放置反面自定义用户控件 -->                        <Page:Win2 Width="400" Height="400"/>                    </Viewport2DVisual3D.Visual>                </Viewport2DVisual3D>                <ContainerUIElement3D.Transform>                    <RotateTransform3D>                        <RotateTransform3D.Rotation>                            <!-- 设置旋转轴为对齐坐标系统的Y轴 -->                            <AxisAngleRotation3D x:Name="aar" Angle="0" Axis="0 1 0"/>                        </RotateTransform3D.Rotation>                    </RotateTransform3D>                </ContainerUIElement3D.Transform>            </ContainerUIElement3D>            <ModelVisual3D>                <ModelVisual3D.Content>                    <!-- 设置指定方向传播的平行光线填充场景 -->                    <DirectionalLight Color="Transparent"/>                </ModelVisual3D.Content>            </ModelVisual3D>        </Viewport3D.Children>    </Viewport3D></Grid>

private void Grid_MouseDown(object sender, MouseButtonEventArgs e){    DoubleAnimation da = new DoubleAnimation();    da.Duration = new Duration(TimeSpan.FromSeconds(1));    if (e.ClickCount == 2)        da.To = 0d;    else        da.To = 180d;    AxisAngleRotation3D aar = Application.Current.MainWindow.FindName("aar") as AxisAngleRotation3D;    aar.BeginAnimation(AxisAngleRotation3D.AngleProperty, da);  }