[Mesa-users] trouble with mipmap minification filtering

[David Hart]

So, I'm still trying to get mipmapping to work. I've spent countless hours
now trying to build and link Mesa the right way on mac and linux and
realizing I may be in over my head trying to reproduce this problem in a C
program.

But I have discovered one very important detail: Mip-mapping is working
fine for me when I use the old fixed-function pipeline in Mesa, it only
breaks as soon as I start using shaders.

Also, I can nudge the LOD level manually even when using shaders, but the
default LOD with Mesa & shaders is always sampling the base level mipmap
for me.

Here is a pyopengl sketch of all the combinations of Mesa vs native OpenGL,
fixed-function vs shaders, and using the default LOD vs modifying the LOD
level manually. I'm drawing two polygons, one is distorted by perspective,
the other is drawn with an ortho projection and distorted by moving two
verts close together. I have dyed each mipmap level with a different color,
so the only thing I'm looking for is multiple colors in both polygons. As
you can see, there is only one case where I don't get any colors other than
the blue base mipmap level, which is Mesa+shaders without manually setting
LOD.

https://dl.dropboxusercontent.com/u/364079/mesa-mipmap/version3/mipmap.html

I'm still running the exact same code through native OpenGL vs Mesa and
getting wildly different results when using shaders. Am I doing something
wrong?

--
David.
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