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This is most certainly not faster than using the tangents calculated by the engine.. why would you think that? Tangents are calculated once only, not every frame...otherwise it would be super slow.


Oh yes, ofcourse.. I was thinking about this quote of the manual, but ofcourse it only applies to animated models and certainly not terrains or static entities:
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On animated models the tangents have to be recalculated every frame, affecting the frame rate, so don't use this flag unnecessarily.



The reason it works is that with terrains, you know the texture coords of nearby vertices since it's a regular grid (also on the uv map).

I find it strange that you get tangents set to 0.. What version are you using, xXxGuitar? From my tests I did get correct tangents for terrains in 6.50.. The ent_fixnormals, I think, just solved a problem with an old .mdl format in the 6.50 engine.

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