Frame buffer access

nobody wrote on Thursday, February 24, 2005:

Is there an issue to access frame buffer to read pixels very fast (i need it to do a method like glVideoCapture)
sorry for my bad english

marcus256 wrote on Saturday, March 05, 2005:

Well, glReadPixels/glWritePixels should work. I don’t know of any aleternate methods (except for using textures and rendering textured quads instead of glWritePixels).

Perhaps I’m missing the point here?

shenron_fr wrote on Monday, April 04, 2005:

Hello, i’m the guy who post the first request, thank for your answer, i know the glReadPixels feature but th GL engine (i mean opengl himself) convert pixels to the format needed and this is (relatively) time consumption.

Under win32, you can use a bitblt method to transfert memory to memory a big amount of data so using this method to transfert the framebuffer to an array used for video output is pretty fast, but i don’t know a faster method than glReadPixels

SDL also have a fast method to transfert frame buffer into a destination array without converting pixels (sorry but SDL web site is actually too slow and i can’t remember the method’s name)

I may use SDL but i like (and prefer) GLFW specially because this is a statically linkable library (not a dll) and this is a small library without unneeded stuffs
good work

ps: sorry if my english is not so good

shenron_fr wrote on Monday, April 04, 2005:

the method for direct access to frame buffer under SDL is SDL_GetVideoSurface (eventually, you need to use SDL_LockSurface to access it)

you can see documention about the method here :