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localjb
02-04-2013, 08:26 AM
Hello. I have been googling and it says you can create hardware overlay with GLUT. And i tried to do that with

establishOverlay() in my program, but it says that GLUT doesnt support RGBA overlays.
Soo i was wondering how am i suppose to do a overlay.

What im trying to do is a black screen overlay, 200x200 where i can draw stuff on it


any ideas?
doing it in c++

tonyo_au
02-04-2013, 11:04 PM
There is no automatic support for overlays in OpenGL. You need to render to offscreen buffers and merge with some sort of blit. Do you know how to render to an off-screen buffer?

Often you don't need to do this - for some thing like with a HUD you render your objects, then disable depth buffer tests and render your HUD

thokra
02-04-2013, 11:48 PM
You need to render to offscreen buffers and merge with some sort of blit.

Let's not get confused here. Blitting is not meant for compositing - blitting is scaling or non-scaling, partial or full a copy operation. You copy contents of one or multiple attachments to all active draw buffers.

EDIT: Scratch that. It wasn't thought through - and I don't mean the blitting part. ;)