[PD-dev] Gem CVS Bug (wrong alarm ??)

[chris clepper]

>I think that it's a good idea to keep separate pix_texture and pix_texture2
>objects because power of 2 textures work differently from non-pow2 textures,
>no matter what tricks/extensions you use to allow the use of non-pow2
>textures.   These differences are in the support for wrap modes, borders
>etc.
>
>Presently, a non-pow2 texture using texture coord scaling (as implemented by
>pix_texture2) will repeat but will include the black padding zones.  Using
>GL_TEXTURE_RECTANGLE_NV repeat is not supported at all.

no if you give the coords in 0..height 0..width it will cover the 
surface completely.

>These behavioural differences can't be properly hidden, can they?  And
>sooner or later it would be nice to expose the wrap mode and border settings
>for control via messages to the pix_textureX object...

yes.  the option for the user to do wrap or clamp_to_edge would be nice.

>Details for nVidia's non-pow2 extension.
>http://www.nvidia.com/dev_content/nvopenglspecs/GL_NV_texture_rectangle.txt

thanks for the info.  this looks pretty close to the apple extension.

>
>>  ...well, at least for the MacOSX build, we need both
>texture/texture2...this is because
>>  we use an extension for non-power of 2 textures that makes for incredibly
>fast
>>  performance...unfortunately, I don't know if the extension
>(GL_TEXTURE_RECTANGLE_EXT) is
>  > available on other platforms?
>
>Notwithstanding what I said above, the fast texture support on Mac OS X
>doesn't need to be used with non-pow2 textures, does it?

no, but it sure cuts down on wasted bandwidth.  640*480 is a hell of 
a lot fewer pixels than 1024*1024.  also IMHO the power of two 
texture thing is just plain silly.  how many images do you run across 
that conform to this?

>The texture rectangle extension is available in the nvidia drivers... not
>sure about other vendors or MESA.

it would be good to check the support for this under linux and windows.

cgc

>
>Daniel
>
>
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