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View Full Version : drawing pixels on screen VS texturing quad



blessman11
04-13-2011, 02:41 PM
I've heard that texturing a quad is faster than drawing pixels on the screen directly. Anyhow, I've come to believe this yet I can't recall where its officially stated by Open GL.

I need this info as reference for uni coursework and was just wondering whether you guys new.

Alfonse Reinheart
04-13-2011, 03:10 PM
Anyhow, I've come to believe this yet I can't recall where its officially stated by Open GL.

OpenGL is a specification. It describes behavior, not performance. Therefore, there is nothing that is or will ever be "officially stated" about this.

However, it is very simple and obvious, by the nature of GPUs and CPUs. Textures live on the GPU. glDrawPixels reads from CPU memory. Even in the best possible case, where the CPU and GPU share memory, glDrawPixels can only be equal in performance to rendering a quad.

blessman11
04-13-2011, 06:25 PM
thanks, now if only I can an alternate reference for it.

ZbuffeR
04-14-2011, 04:09 AM
missing "find" in your sentence maybe ?
The alternate reference is you doing a benchmark program, comparing the speed of both methods.

Kopelrativ
04-14-2011, 06:09 AM
I don't think glDrawPixels() is available in OpenGL 3.3 if you don't use a compatibility context.

blessman11
04-14-2011, 01:27 PM
its quite strange being dyslexic as programmer. Or maybe its microsoft word and rush typing the issue.

I just wish I could, I currently desperately running out of time since why game isn't complete yet and my deadline is in a week at most