I'm looking for a technique to render an object with multiple texture sources. One texture is static, the other is generated dynamically (it's a render target). For example, say I was rendering a TV. The frame of the TV is a static texture and the image comes from a render-to-texture pass.
It doesn't sound difficult but I've been unable to find a decent approach. Some of my ideas are:
Instead of rendering to a unique texture I render to a part of the other texture (so the part with the TV screen is overwritten, the frame remains). This doesn't work if I want to combine multiple textures (two TVs with different frames, same show playing)
Create a two-part object: render the TV frame as one-object then render the image as another. This would require leaving a hole in the one model, or putting the other model slightly on top. Is there a drawback to this approach?
Is there another approach that works well?