Andy Ross writes:
> Curtis L. Olson wrote:
> > I should mention before we get too far that glPolygonOffset is not
> > always consistantly implimented across cards/drivers.
> 
> Is that really true anymore?  I know it used to be true ~5 years ago
> in the era of "QuakeGL", but today things are really quite stable.
> The glPolygonOffset mechanism is the basis for doing multipass
> rendering, and multipass is pervasive.
> 
> Are there really any platforms today (that can run FlightGear
> acceptably) that don't have a solid PolygonOffset implementation?

I've never used this function myself but ....  I'm pretty sure it
works on GeForce cards.  I would assume that it worked on ATI cards
(although they might require different parameter tweaking to achieve
the same results.)  The issue is that the parameters you pass to
glPolygonOffset tie into the internal implimentation of the card which
is obviously different from vendor to vendor and thus you will likely
see at least some rendering differences with the same parameter set if
you use a different card.  The one I'd be most concerned about is the
Voodoo/3dfx line of cards.  I think if it works ok there we should be
good because it should also work on all other modern cards.  But we
may need to tweak the actual parameters for each card (maybe/maybe
not) but if so that could get a little cumbersome.

Regards,

Curt.
-- 
Curtis Olson   IVLab / HumanFIRST Program       FlightGear Project
Twin Cities    [EMAIL PROTECTED]                  [EMAIL PROTECTED]
Minnesota      http://www.menet.umn.edu/~curt   http://www.flightgear.org

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