Scott McMillan wrote:
>
> Scott McMillan wrote:
> >
> > I have been playing with scaling the texture matrix and I have
> > come across a weird result on my Linux box running Mesa 3.0
> > (that doesn't show up on my SGI at work).
> >
> > The attached program scales the texture matrix (2, 2, 0), and
> > renders a textured triangle strip with texture coords in the
> > range [0, 1] (the result looks like I have an identity texture
> > matrix with texture coords in the range [0, 2] and I have set
> > clamp.
> >
> > The resulting texturing gets messed up in area outside the normal
> > texture (where the CLAMP causes the edge pixel to be "stretched"
> > across the polygon), but (and this is the good part) ONLY WHEN THE
> > POLYGON GETS TOO CLOSE TO THE VIEW.
> >
> > Can anyone else recreate this in current beta versions (I am still
> > trying to set up CVS at home)? If so, is this a bug or just an
> > area outside of the spec?
>
> I still need someone to answer the last question above. If this is
> not a bug, somebody please tell me and I will discontinue this traffic.
>
> I checked out the CVS repository version last night and tried the
> program there, and it behaves slightly differently than version 3.0.
> Note again that this occurs in the painting (is shading the right word)
> of the textured triangles ONLY in regions where the texture coordinates
> exceed 1.0 and GL_CLAMP is being used.
>
> Here's more info:
>
> In Mesa 3.0, the texture (which is an orange and black checkerboard)
> is rendered as gray and black in this region when the polygon gets
> too close to the view. In MesaCVS, it is rendered all white in
> GL_DECAL mode and all black in GL_MODULATE.
>
> Scaling the texture matrix has nothing to do with it. Instead of
> scaling by two, I can double the texture coordinates and get the same
> affect.
>
> How close the polygon must be to the viewer to see this affect is
> affected by how large the texture coordinates get.
>
> Using GL_REPEAT does exhibit this problem.
>
> As this is my first look at the Mesa code I am still unfamiliar with
> the layout so I am incapable of tracking this bug down any time soon.
I haven't been able to reproduce your exact problem but I have found
a problem in texture sampling when using GL_CLAMP with GL_LINEAR
sampling.
It seems the cvs server is down so I can't commit my changes. I'll
do so ASAP and let you know.
-Brian
----------------------------------------------------------------------
Brian Paul Avid Technology / Softimage [EMAIL PROTECTED]
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