Andreas, Your conclusion is correct: GL_MAX_TEXTURE_UNITS reports the maximum number of texture units you can access using FFP multitexturing.
Multipass rendering is an option if you don't want to use shaders. Glenn Waldron / @glennwaldron On Fri, Dec 27, 2013 at 4:37 AM, Andreas Ekstrand < [email protected]> wrote: > Hi, > > I'm experiencing some problems with multi-texturing and the maximum > texture units. The attached .osg file works fine on my old ATI HD5800 > (skymap.jpg on layer 0 and detail.jpg on layer 4) but the detail texture at > layer 4 fails on a newer Geforce GTX580, it simply doesn't show. > > Checking the setting of _glMaxTextureUnits in > State::initializeExtensionProcs, my old ATI card gives > GL_MAX_COMBINED_TEXTURE_IMAGE_UNITS = 32 which is used since the GL version > is at least 2.0. And in Texture::Extensions::Extensions, _numTextureUnits > is set to GL_MAX_TEXTURE_IMAGE_UNITS = 16. The newer Geforce card seems to > use even better values, GL_MAX_COMBINED_TEXTURE_IMAGE_UNITS = 192 and > GL_MAX_TEXTURE_IMAGE_UNITS = 32. So this all seems correct, even if these > values don't seem to be used or printed anywhere (?). > > So my conclusion is that since I'm not using shaders, but old-fasioned > fixed-funtion multi-texturing, the GL_MAX_TEXTURE_UNITS actually sets the > limit anyway. In the attached example I could of course use layer 1 instead > of layer 4, but this is only to illustrate a more general case where one > would want to use 4 layers or more in total, simultaneously. Besides > implementing all this with shaders (which I'd rather not do right now), is > there any way of making it work on newer hardware with this low maximum > number of texture units? Any compatibility mode or other tricks to bypass > this limit? > > Regards, > Andreas > > > > _______________________________________________ > osg-users mailing list > [email protected] > http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org > >
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