Rotate 3D cube in WPF - wpf

Question

I make a 3D cube in WPF with the XAML code like this:
<Viewport3D Name="viewport3D1">
<Viewport3D.Camera>
<PerspectiveCamera x:Name="camMain" Position="6 5 4" LookDirection="-6 -5 -4">
</PerspectiveCamera>
</Viewport3D.Camera>
<ModelVisual3D>
<ModelVisual3D.Content>
<DirectionalLight x:Name="dirLightMain" Direction="-1,-1,-1">
</DirectionalLight>
</ModelVisual3D.Content>
</ModelVisual3D>
<ModelVisual3D>
<ModelVisual3D.Content>
<GeometryModel3D>
<GeometryModel3D.Geometry>
<MeshGeometry3D x:Name="meshMain"
Positions="0 0 0 1 0 0 0 1 0 1 1 0 0 0 1 1 0 1 0 1 1 1 1 1"
TriangleIndices="2 3 1 2 1 0 7 1 3 7 5 1 6 5 7 6 4 5 6 2 0 2 0 4 2 7 3 2 6 7 0 1 5 0 5 4">
</MeshGeometry3D>
</GeometryModel3D.Geometry>
<GeometryModel3D.Material>
<DiffuseMaterial x:Name="matDiffuseMain">
<DiffuseMaterial.Brush>
<SolidColorBrush Color="Red"/>
</DiffuseMaterial.Brush>
</DiffuseMaterial>
</GeometryModel3D.Material>
</GeometryModel3D>
</ModelVisual3D.Content>
</ModelVisual3D>
</Viewport3D>
Then is constructor of my window, I want to apply rotations around axis OX, OY, OZ which I think is supposed to be done like this:
RotateTransform3D myRotateTransform = new RotateTransform3D(new AxisAngleRotation3D(new Vector3D(0, 2, 0), 1));
meshMain.Transform=myRotateTransform;
// etc...
It seems I don't apply transform to proper node of XAML, what it the right way to effect transform in my case?

Answer 1

You need to give your ModelVisual3D a name, MeshGeometry3D does not have a Transform Property where as the Model does. You also need to have access to your AxisAngleRotation3D object in order to set the Angle property.
<ModelVisual3D x:Name="MyModel">
....
Edit added more code for CodeBehind method
public partial class MainWindow : Window
{
AxisAngleRotation3D ax3d;
public MainWindow()
{
InitializeComponent();
ax3d = new AxisAngleRotation3D(new Vector3D(0, 2, 0), 1);
RotateTransform3D myRotateTransform = new RotateTransform3D(ax3d);
MyModel.Transform = myRotateTransform;
}
private void button1_Click(object sender, RoutedEventArgs e)
{
ax3d.Angle += 1 ;
}
}
Though in this case I think you would be better off implementing your Transform in the Xaml.
<Window x:Class="WpfApplication1.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="MainWindow" Height="350" Width="525">
<Grid>
<Viewport3D Name="viewport3D1">
<Viewport3D.Camera>
<PerspectiveCamera x:Name="camMain" Position="6 5 4" LookDirection="-6 -5 -4">
</PerspectiveCamera>
</Viewport3D.Camera>
<ModelVisual3D>
<ModelVisual3D.Content>
<DirectionalLight x:Name="dirLightMain" Direction="-1,-1,-1">
</DirectionalLight>
</ModelVisual3D.Content>
</ModelVisual3D>
<ModelVisual3D x:Name="MyModel">
<ModelVisual3D.Content>
<GeometryModel3D>
<GeometryModel3D.Geometry>
<MeshGeometry3D x:Name="meshMain"
Positions="0 0 0 1 0 0 0 1 0 1 1 0 0 0 1 1 0 1 0 1 1 1 1 1"
TriangleIndices="2 3 1 2 1 0 7 1 3 7 5 1 6 5 7 6 4 5 6 2 0 2 0 4 2 7 3 2 6 7 0 1 5 0 5 4">
</MeshGeometry3D>
</GeometryModel3D.Geometry>
<GeometryModel3D.Material>
<DiffuseMaterial x:Name="matDiffuseMain">
<DiffuseMaterial.Brush>
<SolidColorBrush Color="Red"/>
</DiffuseMaterial.Brush>
</DiffuseMaterial>
</GeometryModel3D.Material>
</GeometryModel3D>
</ModelVisual3D.Content>
<ModelVisual3D.Transform>
<RotateTransform3D>
<RotateTransform3D.Rotation>
<AxisAngleRotation3D x:Name="rotate" Axis="0 2 0"/>
</RotateTransform3D.Rotation>
</RotateTransform3D>
</ModelVisual3D.Transform>
</ModelVisual3D>
</Viewport3D>
<Slider Height="23" HorizontalAlignment="Left"
Margin="12,12,0,0" Name="slider1"
VerticalAlignment="Top" Width="187"
Maximum="360"
Value="{Binding ElementName=rotate, Path=Angle}" />
</Grid>
</Window>
Also with this example you can change your AxisAngleRotation3D in the CodeBehind by setting its Angle Property:
rotate.Angle +=1;