(LWJGL) Subdivision of the Display

OpenGL Development
#1

Greetings!

I’m currently working on the basics of my lwjgl-project and got the following question:
How can I subdivide my Display into different parts? I need something like different clipping-panes for different parts. I think there is something in the fixed-function pipeline but I want to use non-deprecated OpenGL only!

To give you an example:
Say, I want to divide my display into two equally big parts (part 1 & 2) (vertically). I then want to render objects of type A to part 1 and objects of type B to part 2. Both should be clipped when crossing the vertical “boarderline”.

One possible solution I already tested is simple discarding the fragments out of my imaginary clipping pane via frag-shader. But this seems like a rather ugly solution because I’d have to implement that in every frag-shader and so every object. I’m looking for a better option to to this.

Thank you in advance!

#2

What you’re looking for is glViewport. You can find a tutorial for using it at http://nehe.gamedev.net/tutorial/multiple_viewports/20002/ - it’s the usual disaster of chopped up formatting and windows boilerplate that is a NeHe tutorial, but if you scroll to the bottom there’s source code in other languages. The python version should be pretty readable.

#3

Viewports are the way to go as already suggested.

One thing to bear in mind is that glViewport is essentially defining a new ‘window’ (for want of a better term), so you will want to setup a different projection for each one (they will have different dimensions for a start), perhaps different background colours, different scenes (your A in one, B in t’other), etc.