On Wed, Feb 16, 2000 at 01:54:51PM -0700, Brian Paul wrote:
> > Where can I find information about the values in ctx->ProjectionMatrix?
>
> Not sure I understand your question.
Where are the values for ctx->ProjectionMatrix generated? I assume
they're from a series of:
glMatrixMode( GL_PROJECTION );
glLoadIdentity( );
glOrtho( 0, w, h, 0, 0, 1.0 );
style API calls. The question is poor, I admit. I was just wondering
why certain values where, say, -1, or even, according to gdb -0 (ie,
if this is out of the ordinary), and if these values were perhaps due
to my rendering setup (below).
> I guess I'll need more info on your "rasterization only interface".
I do all of my own transformation, clipping and projection. The only
manipulation of the modelview or projection matrices comes from a call
to glOrtho(). All vertices are specified with x,y screen coordinates
and a z value between 0 and -1.0. The texture coordinates are supplied
with a homogenous w coordinate.
> I was working on a bug fix for LINEAR fog in the 3dfx driver yesterday.
> Maybe related?
This is actually with the software renderer. I was able to resolve
these issues by fiddling with the start/end. For a glOrtho with 0,1.0
near/far I got appropriate fogging by setting the start to 0.995 and
the end to 1.0. I assume this is because a great deal of my data is
clustered towards the far clip plane (terrain data).
However, I am currently exploring a problem with the GL_LINEAR FX fog
mode, but I was looking into why all of my oow coordinates are set to
1.0 in my grVertex structures.
There did seem to be a large problem with the way the fog tables were
calculated for FX, given that I got a table filled with 0xFF for the
start/end I described above.
> You're looking at _mesa_fog_rgba_pixel()? The sign of eyez doesn't
> really matter since for LINEAR and EXP we use the absolute vale and
> in the EXP2 case we're squaring that value.
What about the zero values for tmp I was seeing (0 value for the
variable 'd' in gl_fog_rgba_pixels())? This was causing no fogging in
the EXP and EXP2 cases because eyez always ended up as 0, f became
2.81, clamped to 1.0, and no fogging provided.
m.
--
Programmer "I wrote a song about dental floss,
Loki Entertainment Software but did anyone's teeth get cleaner?"
http://lokigames.com/~briareos/ - Frank Zappa, re: the PMRC
_______________________________________________
Mesa-dev maillist - [EMAIL PROTECTED]
http://lists.mesa3d.org/mailman/listinfo/mesa-dev
