I'm trying to render a mesh ("content mesh") (with depth testing) only when it is behind another mesh ("window mesh").
The first solution would be to use a stencil buffer to only write where the "window mesh" has been written.
My issue is that the "content mesh" can be in front of the "window mesh", and I want to discard the fragments in this case (only visible if behind).
I can simply save the depth coordinates of the "window mesh" in a texture, and discard fragments of the "content mesh" using that information.
However, this implies a texture look-up and the use of 16 bit floating point numbers for the custom deph-test.
Is there another way to do this ?
PS : How to render a mesh behind another mesh, like a mask? This thread almost got me the solution but in my case I don't want to render at all the "content mesh" when it is in front of the "window mesh".
I used a texture to store the depth, and used it to discard fragment that are closer than this depth. It works fine. I'm satisfied enough with that.