[SDL] Speeding up glClear?

Johannes Schmidt sdl at myrealbox.com
Fri Jan 7 04:59:33 PST 2005


On Thursday 06 January 2005 18:40, Steve Smith wrote:
> I get the sense that this is kind of an eternal question, but it's
> been driving me a bit batty.  I've been running some timing on a very
> simple 3D maze program to try to figure out why my framerates are so
> low on older machines - for instance, my P2 550 runs it at about 4
> frames per second.  The timing indicates that the call each frame of:
>
> glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT)
>
> takes over 250 ms to complete at 800x600 fullscreen resolution.

Huh?
Sorry, I have to ask:
Are you really sure that it is glClear that takes this long?
glClear just fills the buffers with 0's or the given clear color.

Every software renderer does a better job on this.

I am running my apps using Mesa software rendering and an Athlon 700 Mhz with 
quite a decent frame rate.

Regards,
Johannes

< http://libufo.sourceforge.net > The OpenGL GUI Toolkit




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