Immediate mode rendering is dead

[gouessej]

@princec

I find now that as soon as I perform immediate mode rendering in OpenGL, performance rapidly plummets back down to terrible.

It would appear that VBOs are kind of an all-or-nothing approach; any immediate mode rendering pretty much buggers the whole advantage of VBO usage up. So now I have to port all my text rendering, background rendering, capacitor zap rendering, building under attack rendering, and powerup beam in effect rendering to use VBOs instead of immediate mode. Bah.

Hi!

Sorry to refresh this old thread. Do you mean that mixing a lot of VBO with even a tiny use of immediate mode is noticeably slower than using only VBOs? If so, why?

[princec]

I suspect that as soon as you involve immediate mode it completely buggers the nice interleaved VBO pipelines you’ve got all set up and the drivers have to turn off a whole load of optimisations. Not to mention the fact that it’ll probably stall the pipelines. And the driver writers most likely don’t optimise the immediate mode path any more as nobody’s supposed to be using it.

Cas

[gouessej]

Thank you very much for your explanation.