Re: [Mesa3d-dev] Bug in z-depth

[Allen A. <ak...@po...>]

Hi, Dave!

On Fri, Oct 06, 2000 at 11:29:30AM -0700, Dave Shreiner wrote:
| 
|    However, its not as if people have been unsuccessful using
| glXChooseVisual().  ...

It seems clear to me that people aren't making a lot of use of the
alternatives, e.g.  visinfo has been around since 1994 and most OpenGL
people I know have never heard of it.  But screwups with
glXChooseVisual() are really common.  My experience is that most
people just experiment until they find some combination of input
parameters that works, and then stick with that until the app is run
on some other OpenGL implementation and breaks there.

|    Personally, I would vote for something in the spirit of "isfast".

That's the way visinfo was distributed originally, but apparently it
never caught on.

|    On the (larger, IMO) con side, generic use of an alternative visual
| selection algorithm (which probably isn't needed in many cases anyhow),
| means that as new features become "default" (like multisampling) for
| visuals, these changes should be transparently folded into something
| like glXChooseVisual() without requiring modification of the developer's
| code. 

The same thing can be done with visinfo as long as it's in a dynamic
library.  (BTW, visinfo already has multisampling support, provided in
an upward-compatible way like glXChooseVisual().)

|    I don't think glXChooseVisual() sucks so bad that an alternative
| needs to be standardized.  Not to slight the work that Allan's done, but
| a faster, and easier, solution would be some better documentation of how
| to choose visual.

Could be.  I haven't pushed the issue in years because it was just too
low on the priority list.  But in the long run, I feel pretty
confident that people who give up on glXChooseVisual() and switch to
calling glXGetConfig() to do their own visual selection will
eventually just duplicate the effort that went into visinfo.  Might as
well save them some work...

Allen