Vista - adorning problems

Hi All,

Im trying to build an Adorner that incorporates a Viewport3D. I seem to
be having a lot of trouble getting the Viewport3D to appear, or even to
acquire a non-zero size.

Once I get the Viewport3D to appear, Im going to want to move it around
following the mouse.

Can anyone point out what I am doing wrong?


public partial class Window1 : Window
{
private Lens _lens;

public Window1()
{
InitializeComponent();
}

private void OnLoaded(object sender, RoutedEventArgs e)
{
Console.WriteLine("OnLoaded");

ScrollContentPresenter scp = VisualUtilities.GetVisualChild(this, 0,
0, 0, 0, 0, 0, 0, 0) as ScrollContentPresenter;

this._lens = new Lens(100, 20, scp);
AdornerLayer layer = AdornerLayer.GetAdornerLayer(scp);
layer.Add(this._lens);

e.Handled = true;
}
}
public class Lens : Adorner
{
private Viewport3D _viewport;

public Lens(double radius, int points, UIElement element) :
base(element)
{
this._element = element;

this._viewport = new Viewport3D();
this._viewport.Camera = new OrthographicCamera(new Point3D(0, 0, 1),
new Vector3D(0, 0, -1), new Vector3D(0, 1, 0),
element.RenderSize.Width);
this._viewport.I****TestVisible = false;
this._viewport.Width = element.RenderSize.Width;
this._viewport.Height = element.RenderSize.Height;

this._viewport.Children.Add(this.CreateLensModel3D(radius, points));

// not sure what exactly is _necessary_ here, but trying everything

this.AddVisualChild(this._viewport);
this.AddLogicalChild(this._viewport); // AddLogicalChild seems to
ensure that _viewport has a Parent

}

protected override int VisualChildrenCount
{
get { return 1; }
}

protected override Visual GetVisualChild(int index)
{
Console.WriteLine("GetVisualChild " + index);
if (index == 0)
return this._viewport;
else
throw new IndexOutOfRangeException();
}
}