General ofFbo question

I’m drawing a bunch of things to an fbo because I’d like to warp them all on the same texture (some keystoning for a projector). Is there any disadvantage to drawing everything to the same texture, or should I be splitting them up into different fbo’s? How is this sort of thing generally handled? Drawbacks? Thanks a bunch.

Hey sharkbox,

I think it largely depends on your needs. ofFBO supports depth data, so you can render objects in 3D space and it will render correctly in the fbo.

I am not sure about the performance decrease, but based on this post, doesn’t seem like there is much of a drop in rendering multiple fbos.
http://www.gamedev.net/topic/593428-lwjgl-fbo-performance/

You can break up drawing into FBO’s if you want to apply different shaders or effects to different fbos. One example would be a glow effect outlined by the gpu gems book.
http://http.developer.nvidia.com/GPUGems/gpugems-ch21.html

Also, a great thread on quad warping without opencv that may be of some interest to you.
http://forum.openframeworks.cc/t/quad-warping–homography-without-opencv/3121/0

Cheers,
Nick

nick, you’re a prince.

Hi,
i am trying to do the same, but got no good results. (of 007, mac).

did you?
how??
thanks !

Hey miguel,
I ended up using a couple shaders so I drew to a couple of fbos that I could use shaders on, and then drew it all to one big fbo which seems pretty quick. Then to do keystoning I’m using theo’s method from here: http://forum.openframeworks.cc/t/quad-warping-an-entire-opengl-view-solved/509/0