Re: Graphics cards
- From: "John A. Byerly" <johnbREMOVE@xxxxxxxxxxxxxxxxxxxxx>
- Date: Thu, 23 Aug 2007 18:34:21 GMT
Thanks for the information (from fungus, too)!
I mentioned that I wasn't wanting brand recommendations because I didn't
want my post to be taken as a troll (NVIDIA rules, ATI sucks, that sort of
thing).
We have seen some significant variances in the performance of our app and we
are trying to get our arms around the problem. Our best intelligence so far
is that it is related to the amount of dedicated memory (vs. shared) for the
graphics system. The app performs well on some laptops, not as well on
others. The trend with desktops seems to be that our app running on a
system with on-board graphics doesn't perform well at all. Those with a
graphics card fare much better.
Our app draws lines and polygons exclusively (no textures), but we tend to
have a gazillion vertices. We make heavy use of display lists, which has
boosted performance considerably. We investigated using vertex arrays, but
this was not a viable option given our requirements.
One puzzling thing was the difference in the handling of double buffering.
On some systems, double buffering works fine. The animation is smooth. On
other systems, it is as if every other move is drawn to a buffer, with the
result being a flickering back and forth between odd and even renderings. I
am sure that double buffering works on all of these systems, but with the
flickering ones, we use single buffering. It works, but the animation is
choppy.
JAB
"Philipp Klaus Krause" <pkk@xxxxxxx> wrote in message
news:46c5afc9$0$11216$6e1ede2f@xxxxxxxxxxxxxxxxx
John A. Byerly schrieb:
Hi,
I was hoping to get some insight as to what constitutes a "good" PC
graphics
card. I am not asking for brand recommendations, but rather for the
characteristics of a graphics card that make one better than another. If
this information is in an FAQ, please accept my apologies (but also
supply a
link to the FAQ ;-)
Also, do some PC graphics cards support OpenGL better and others support
DirectX better?
This is difficult without brand recommendations since it depends on
vendor policy a lot. The small ones like SiS are struggling with
providing Direct3D drivers, don't expect much OpenGL support from them.
This leaves 3Dlabs and the big three (Intel, Nvidia, ATI).
3Dlabs has left the graphics card market, but their Wildcat Realizm
cards are probably still good OpenGL 2.x cards.
Intel gives specifications of their chips to developers, so they have
excellent Linux and FreeBSD support, however OpenGL driver quality is
said to be lacking on Windows. Their newest chips can do OpenGL 2.x, but
the drivers don't support it yet. While Intel is the market leader
they're far behind Nvidia, ATI and 3Dlabs in performance.
Both Nvidia and ATI support OpenGL in their closed-source drivers on
both Windows and Linux. Their cards are similar with then newer models
having good shader support.
Now for the vendor-independent stuff (mostly useful for comprisons of
ATI and Nvidia cards):
-Memory bandwidth is important for texturing and buffer updates.
-There's differences in shader support like number of fragment/vertex
processors, maximum shader length, maximum number of texture lookups, etc
-Amount of memory: Loading textures from main meory is slow, so a large
on-card memory will improve speed when using many large textures
-Power consumption: Highend cards need huge amounts of power, which is
expensive, needs an expensive power supply, requires a lot of cooling
which makes a lot of noise.
Philipp
Philipp
.
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- From: John A. Byerly
- Re: Graphics cards
- From: Philipp Klaus Krause
- Graphics cards
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