Hi Sherman,

I haven't noticed particular problems with NPOT textures once
rendering is underway, but the initial generation of the mipmaps was a
bottleneck on XP/Nvidia driver was recently found to be very very slow
(like 500ms+ instead of the normal 5-50ms for this type of op).  The
fix submitted for this was to use the relatively new generate mipmap
extension, rather than rely on the older generate mip hardware
extension, this fixed the performance.  This fix is now in SVN, and
will be part of the 2.5.3 release that I'm planning for tomorrow.


On Sun, Jun 22, 2008 at 2:06 AM, sherman wilcox
> In the olden days when I'd have a texture that wasn't power of 2 I'd
> use a POT (power of two) texture, update the parts of the texture that
> I was interested in and fix-up the texture coordinates accordingly.
> Nowadays I'm more inclined to use NPOT (non-power of two) or texture
> rectangles. Problem is every time I try to use NPOT textures I get
> nailed performance wise. If I use texture rectangles no problem -
> performance is as you'd expect...it just works. The thing I don't like
> about texture rectangles primarily are the lack of NDC
> (non-dimensional coordinates). Maybe I'm old fashioned, but I like my
> coordinates to be in the range of 0 - 1. Oh, and the lack of mipmaps
> are rather disappointing as well, but a small price to pay when you
> really only need a 2049 x 1025 texture.
> So, what's your experience? Anyone out there sucessfully using NPOT
> (not texture rectangles) in the OSG? What's your video
> hardware/OS/driver? I'm using some very good nVidia cards (FX4600)
> with the latest drivers on Vista - but NPOT performance is terrible.
> Perhaps I'm doing something boneheaded.
> NPOT - GL_ARB_texture_non_power_of_two:
> http://www.opengl.org/registry/specs/ARB/texture_non_power_of_two.txt
> Texture rectangles - GL_ARB_texture_rectangle:
> http://www.opengl.org/registry/specs/ARB/texture_rectangle.txt
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