Is there any point? Why wouldn''t you just use 2 passes... It''s equally fast, and "safer" -~-The Cow of Darkness-~-

IIRC, It''s because your GFX card has multiple texture units.
So multi-texturing should be closer (in speed) to one-pass rendering, not two pass.
(Since it does both texturing operations at once)

Plus I think some multitexturing effects can''t be done with a multi-pass method, like having the second texture alter the first.

Thanks... I was using a geforce2, but I din''t look at the framerate, I just thought they "looked" the same...

-~-The Cow of Darkness-~-

The main reason is speed. Multiple passes take more time: 2 passes take twice the time of a single pass. But a pass using multitexturing on two units (achieving the same effect) takes only the time of a single pass (almost).

Things get even more interesting, if doing multitexturing on modern hardware with 4 or more units. Doing an effect on 6 units, for example, would require 6 passes without multitexturing ! That''s six times the time of the multitexture approach. And as TravisWells mentioned, most advanced effects cannot be done in multiple passes, due to the texture combining equations used.

Also, from an accuracy point of view, multitexturing is more precise, as it uses much higher precision as multipass blending. The visual quality will be higher, esp. if using lots of passes.