[SDL] OpenGL speed, Linux vs W2000

Daniel Phillips phillips at arcor.de
Thu Jan 23 15:01:01 PST 2003

On Thursday 23 January 2003 21:45, Shawn wrote:
> On Thu, 2003-01-23 at 14:35, Gib Bogle wrote:
> > Now I have to correct a previous statement I made.  I now realize from
> > looking at the output from the program that the W2000 version always
> > sets SDL_GL_DEPTH_SIZE to 16, while the Linux version sets it to 24,
> > regardless of what I try to set it at (16 or 24).  The call
> > SDL_GL_SetAttribute(SDL_GL_DEPTH_SIZE, n) seems to be redundant -
> > commenting it out has no effect.
> This is because X doesn't allow on the fly color depth changes
> currently. The windows one because of some driver setting AFAIK.

SDL_GL_DEPTH_SIZE refers to the number of zbuffer bits, not the X color 
depth, so this has nothing to do with X not being able to change the color 
depth on the fly.  The problem setting the zbuffer depth is a *bug* 
somewhere, which I've started sniffing around at, but have not yet tracked 

SDL does not appear to be the guilty party, as it basically just does 
glXChooseVisual, which screws up in some way that requires delving into Mesa 
and XFree code to understand.



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