Simon,
I haven't noticed any performance degradation (similar to what you
describe) on nVidia hardware.
It sounds like maybe the radeon driver does ok drawing alpha quads (or
quads with an alpha component) from back to front, but perhaps there
is an inefficiency in the pipeline when the alpha quads get obscured
by something in front. That doesn't make a lot of sense to me because
the driver it seems would have to do *less* work in the latter case.
But, perhaps there is some subtle issue in the card/driver that is
causing this?
Curt.
Simon Fowler writes:
While playing around with different versions of the DRI Radeon
drivers today, I noticed an odd thing: with the standard c172 model
in the external view, if I look at the model from head on, I get
20-25 fps, whereas if I look from a perspective where part of the
spinning propeller disk is obscured by the airframe, I get ~6 fps. I
get the same 6 fps all the time when I run with the 3d model.
I'm just curious whether this same effect is seen by anyone else,
particularly people running NVidia hardware - if it's a driver
issue, I'll take this to the DRI devel list.
If it's something to do with FlightGear or plib, it'd be nice if
there was some way to deal with this - being limited to around 6 fps
makes the 3d models almost unusable by me, and I don't have the
money to upgrade to faster hardware . . .
For the record, I have a K7 550, a Radeon QD (32 MB), Linux
2.4.19-pre8, XFree86 4.2.0, and the latest DRI CVS tree, along with
the latest CVS trees from FlightGear, SimGear and plib.
Simon
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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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