A 2D UI with a hole for 3D viewing

My ideal user interface: a 2D woodgrain-looking panel, with some GUI elements on it, and a big square cutout in which the 3D game is displayed. What’s the best way of doing this? I see how to display a texture image as part of render2d, and ideally it would be a repeating texture, rather than coming up with unique woodgrain imagery for the entire screen. But how might I make a “hole”, a region of complete transparency, in the middle of that image?

Could you construct your GUI as four frames, encircling your “cutout”? If the textures are tiled carefully you may be able to do so without seams.

Otherwise, you could perhaps model your frame–complete with central hole–in a 3D modelling program and then provide that to your GUI via the “geom” keyword-parameter.

And finally, I think that a ScissorEffect may allow you to mask out the relevant portion of your GUI–see this thread for more.