[vtkusers] Video in Background of 3D-Scene

[Ingmar Wegner]

Hi,
I searched through the users-list and found some helpful tips on how to 
grab frames with vtkVideoSource (vtkWin32VideoSource).
But I need further information on how to declare the video as 
background, or show the video in background and to be able to draw 
OpenGL- objects in front of it.
3D-interaction isn't really needed, so I might as well use a 2D scene. 
But I need OpenGL to do some buffer calculations so a 3D window might be 
a better choice, right?

So far I use a vtkWin32VideoSource to grab the frames.
1.Is there a way to overcome the update-process, cause the video always 
needs to be updated?

Then I need to render the Video in background. I tried adding the actor 
as the first, but didn't succeed.
I tried the combination with a vtkOpenGLImageActor and a vtkActor2D. The 
vtkActor2D didn't show it in the background, and the vtkOpenGLImageActor 
did show the video as a texture on a plane which i could also interact 
with. An adjustment of the plane, which translates that plane, so it 
always shows the video as background would be possible, but quite dirty!
2. What to take and how to show a video in the background?

3. Then for the OpenGL- context? Is there a nice way to add OpenGL- 
calls at desired places? I need clipping and switching buffers. Or 
should I rather implement a new rendererclass derived from vtkRenderer 
or from vtkRenderWindow?

Thank you in advance,
Ingmar