supporting opengl 1.1

Apprentice
Posts: 6
Joined: 2008.10
Post: #1
the windows game that i'm currently porting to mac relies on the GL_CLAMP_TO_EDGE wrap mode for things to look right on screen. when looking through apple's compatibility matrix for opengl, it looks like some plausible configurations would only support opengl 1.1, and therefore only support GL_CLAMP which by the spec samples from the border color (even though it seems like some nvidia hardware treats it as GL_CLAMP_TO_EDGE anyway.)

my question is, do mac games generally still offer full support for people who can't run anything greater than opengl 1.1? does anyone have a sense for how many machines in the wild would actually fall into that category? the drivers in question are the generic, geforce 2/4mx and rage128.

the only workaround that i can think of would be to manually duplicate the outter-most pixels of all the textures while building data and then change the renderer to only sample from texels (1,1) - (n-1,n-1). this would increase the size of the textures by 2 in each direction though and that would push us into the next power of 2, wasting a bunch of memory (i'm guessing that these old cards don't support non-power of 2 textures.) any other ideas?
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Sage
Posts: 1,232
Joined: 2002.10
Post: #2
Every renderer on Mac OS X exports SGIS_texture_edge_clamp, and therefore supports CLAMP_TO_EDGE, regardless of the OpenGL core version.

You need to look at the extension list in addition to GL_VERSION.
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Luminary
Posts: 5,143
Joined: 2002.04
Post: #3
For example, the Intel GMA 950 supports almost every feature that would be required to support OpenGL 2.0, yet is missing some feature that was made core in 1.3, so it can't claim more than 1.2. The rest of the functionality is exposed via extensions.

I almost always code to OpenGL 1.1 + extensions. There's little benefit to admitting the existence of higher versions of the core spec.
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Apprentice
Posts: 6
Joined: 2008.10
Post: #4
got it. thanks guys.
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