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Re: GL_COMBINE 2 Textures

Hi Alex,

On that note, is there a clever way to interpolate two textures and then modulate by local vertex lighting, in one pass with two texture units, on a Rage128? I ask the list because this is a current question on idevgames. Obviously you can do it with crossbar but that isn't available on all hardware.

I specifically solve this case by using a third tex unit - combine first with the two tex units, use the third to put in the lighting. I needed the third tex unit anyway for some alpha channel ops, so it works ok, but it does cause problems on a lot of 2 TU chipsets like the GF4-MX. :-(

Probably the easier way to do it (only with massive performance hits and game refactoring) would be a multipass algorithm and blending...you really pay for that in framerate though, especially on fill-rate limited hardware.

nvidia drivers only implement GL 1.1 or 1.3, so is it really safe to use TEXTUREn sources? Or must I fool around with texture combiners to be safe?

I always assume it isn't there...would be interesting if it secretly is though. :-)

*cheers*
Ben
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 >Re: GL_COMBINE 2 Textures (From: Alex Eddy <email@hidden>)



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