EGL_MESA_screen_surface proposal

[Adam Jackson]

On Wednesday 16 March 2005 14:23, Jon Smirl wrote:
> On Wed, 16 Mar 2005 12:15:15 -0700, Brian Paul
> > > Color depth is an independent variable to the mode.
> >
> > Is it?  I remember video cards that could support 1024x768 with 24-bit
> > color but 1600x1200 only with 8-bit color.  Was that because of
> > limited DAC bandwidth or the limited amount of VRAM?
>
> That is a hardware limit. If you have a 1600x1200 mode set and you try
> to use a 24b surface you should get an error saying bandwidth
> exceeded. The problem is that 1600x1200-24 outputs at something like
> 150Mhz and your monitor can only take 120Mhz.
>
> You don't want to combine depth into the mode list because the
> modelist with get 10x larger. It is simpler just to return the error
> on an invalid combination. With current equipment this error doesn't
> happen very often.

No, it gets twice as large.  No one cares about color depths that aren't 16 or 
24.  And if they do, they can just suffer along with a larger mode list.  The 
driver layer is not the place to be making decisions about what the user 
might want.

Note that Windows effectively includes color depth in the mode description, 
because if you raise the color depth your maximum resolution goes down.

- ajax
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