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View Full Version : glDrawPixels vs textures



gandalf3373
09-26-2004, 05:21 PM
i need to create some custom skinned ui elements in an app that i am working on. i am just wondering how much of a performance gain i would have by using texture mapped primitives versus rendering them with glDrawPixels since they are all mostly image based and in 2D. due to the aspect ratios of some of them i suppose i would have no choice but to use glDrawPixels. but for some a power of 2 sized image is just fine.
in short, i guess i am just looking for some expert advice on the performance differences between glDrawPixels and texture mapped primitives, cuz i have heard that the latter is faster.

thanks

rgpc
09-26-2004, 06:39 PM
This is not an advanced question.

The short answer is try it and see.

The long answer is think about what you are suggesting. DrawPixels will send your texture(s) across the bus every time you use it. Using a texture will send the texture data across once, and then you send 4 verts across for each quad you draw.

If your textures are non power of 2 then pad them out with blank (Alpha=0) areas and adjust your texture coords to suit - or resize the data, or use the Texture Rectangle extensions.

gandalf3373
09-26-2004, 06:56 PM
thanks.