answers inline below
-----Original Message-----
From: Adam Belmont <Adam Belmont [mailto:[EMAIL PROTECTED]]
Sent: Friday, October 01, 1999 11:38 AM
To: [EMAIL PROTECTED]
Subject: Re: [JAVA3D] Performance issues. How to do it better?
It could also be your graphics card (Assuming you are on WinNT/98).
Some cards that were basically designed to make DirectX games go fast
can't do hardware acceleration in a window. So it's possible that your
CPU is doing the work and not the graphics card.
<
all modern cards, read in the last 3 years, except 3dfx Voodoo1 and Voodoo2
can do 3D hardware acceleration in a window.
Voodoo1 and Voodoo2 are what are known as "secondary" cards that use a
pass-thru cable. they do not contain any 2D hardware and thus no VGA/SVGA
core and cannot render the desktop.
Voodoo1 shipped late '96. there were contemporaneous cards from other
manufacturers ( like PermII, RIVA128,RagePro ) but at the time 3Dfx was top
of the heap; fillrate and features.
>
At home I have a Permedia 8Meg card and at work I have an STB Nvidia
16 meg card. Both machines are PII 400's.
<
PermI or PermII?
if PermI,thats severely dated.
if its PermII, realize that PermII is a 2+ year old card that has ~75% of
the fillrate of the Voodoo1 ( which had 50-60mp back in the day) but lacks
alpha blending modes and so cannot do colored lightmaps ( no
srcalpha/invsrcalpha blend modes if I recollect correctly ).
for comparison with 2nd half of '99 hardware - nVidia geForce has 500mp
fillrate.
>
The 8 meg card at home is much faster than the 16 meg one because it
can do hardware acceleration in a window. The 16 meg card at work is
just terribly slow in comparison.
<
what chipset is in the STB? TNT? its not RIVA128, right? not a RIVAZX?
if thats TNT the result does not make sense, cause a TNT is way better than
a PermII.
what display mode ( width x height x depth )? what rev of the nVidia driver?
are you sure you are getting a hardware rasterizer? and not running on the
software rasterizer?
do you have the DirectX SDK? if so - what does dxdiag tell you? the caps
viewer? how do D3D samples run?
>
I have not tried the DirectX version with full screen mode turned
on. I suppose the performance should improve on the gaming cards when
run in full screen mode.
<
depends.
fullscreen is page-flipped which is usually gated by refresh freq. 60 fps is
usually sufficient for game framerate though. for stereo 120hz refresh is
nice.
windowed is blt and blts are typically not gated by refresh freq. so it is
possible to run faster in windowed mode at the same resolution...
>
But, besides all that. You should display as few polygons as you can
get away with. Perhaps you could use the Level of Detail behavior to
really simplify your display for objects in the distance.
Another thing you can try, which could be quite a bit of work, is to
make your display very very simple when a rotation is occurring.Just
show they bare bones the user would need to see to understand where
everything was. Then, when the rotation stops, go back to a detailed
view.
<
here is a tip to see if you are fillrate-bound or poly-bound:
1st drop rendering resolution ( fewer bits to fill ). if there is no
significant speedup, you are not fillrate-bound.
next drop model resolution at the same rendering ( fewer polys to draw ). if
you dont see a significant speedup, you are not poly-bound.
fillrate is what rasterizer hardware is meant to accelerate.
poly processing typically happens on the CPU, but as consumer hardware that
accelerates transforms ( like nVidia geForce ) becomes prevalent - that will
change the cost equation between graphics hardware and CPU.
tools like VTune and IPeak GPT ( both from Intel ) are recommended for
serious perf optimization work.
>
-- Adam Belmont
<hope this helps>
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