Hi
About 10 days ago I got fed up with low frame rates using OSG around KSFO,
so I went out and bought the best nVidia AGP card that I could find - 7600gs
with 512Mb of VRAM. I fitted it with great anticipation to my machine - P4
2.8Ghz/800Mhz FSB with 1.5 Gb of RAM running XP - and, precisely NOTHING. No
change in frame rate between the new card and the old - a FX6200 with 256Mb
VRAM - for FG-OSG-HEAD. On the other hand plib-HEAD flies. Here are some
comparative results:
Aircraft: Seahawk
OSG PLIB
KSFO General Ocean KSFO General
Ocean
every check box turned to off:
25 30 60 45 80
117
with everything checked, traffic manager on:
15 25 36 25 50
80
as above with shadows and 3d clouds:
18 40
65
as above but with trees and precipitation:
10 15 40 (but the rain turned itself off!)
Aircraft: c172p
every check box turned to off:
33 40 60 45 90
130
with everything checked, traffic manager on:
27 33 40 30 50
75
as above with shadows and 3d clouds:
30 50
65
as above but with trees and precipitation:
15 25 30
Aircraft: Buccaneer (particles)
as above but with trees and precipitation:
8 18 20
In addition to the difference in frame rate, OSG also stutters, while plib
is commendably smooth. I've tried both executables generated here using
MSVC8, and Fred's pre-cooked binaries. So far as I can see the results are
identical. I've profiled both OSG and plib - for anyone interested, some of
the results are here:
ftp://abbeytheatre2.org.uk/fgfs/OSG/
While I am no expert in profiling code, the results seem to me to show that
we are getting stuck in the bowels of OSG somewhere, while plib is
well-ordered, with no particular cpu-hog, which is pretty much what the
above table indicates.
My principle concern is that there appears to be very little headroom for
future developments in OSG for shadows, or 3d clouds, or landing lights, on
what is a not-very-old and pretty capable machine. I would be grateful if
some Windows user(s) could confirm at least the shape of these comparative
results. I understand that Linux users get much better results than these.
We might be getting towards the point when Windows users are stuck with plib
(and that's not all bad) while Linux users get to play with all the new
goodies. We might be drifting away from our cross platform ethic.
Vivian
Luckily the new card wasn't terribly expensive otherwise I would be quite
p'd off
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