Re: Mipmap filtering

[Joseph J. S. <jo...@st...>]

I've checked in Frank's changes for issue 905678.  The code is nice 
and neat, and Frank has verified that this gives the intended result 
with PixmapTextures, while not affecting MipmapTextures (so, if you 
want to avoid the automatic mipmapping, you can just supply a MipMap 
with only one image, and it'll work use that image at any distance).

The filter constants map to OpenGL quality filters as follows:

kQATextureFilter_Fast = Nearest neighbour (ignores mipmaps)

kQATextureFilter_Mid = Bilinear mipmap (ala QD3D 1.6's default)

kQATextureFilter_Best = Trilinear mipmap (not sure what QD3D does 
here, because we don't think hardware back then supported trilinear 
filtering).

Note that the default quality in both QD3D and Quesa is kQATextureFilter_Mid.

Frank noted that we could consider using a custom halving algorithm 
for generating the mipmap images; currently we just let 
gluBuild2DMipmaps do that for us.  He also mentioned the possibility 
of anisotropic filtering, but said that would require some 
discussion, so I'll leave it to him to get that ball rolling if he 
thinks it important.

I'm not sure quite what the proper Tracker procedure is, but here's 
my stab at it: I set the Resolution pop-up to Fixed, but left the 
Status to Open, thinking that we'll Close it when it's actually 
shipped in an official release and the fix has been verified there. 
Somebody please correct me if that's not right.

Thanks,
- Joe

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