Poor OpenGL performance?

Fred · Post by **Fred** » Sat Aug 20, 2005 1:57 am

I finally had time to sit down tonight and start prototyping an idea ofmine. Except I discovered that Irrlicht's OpenGL performance (under Linux and Windows) is poor. The terrain demo gives me 400fps on an AMD64, with 1GB memory and a GeForce 6600GTS.

Is there some specific reason in the OpenGL driver, or is Irrlicht just not making the most of OpenGL's features?

Thanks

luckymutt · Post by **luckymutt** » Sat Aug 20, 2005 2:10 am

How does that compare with the FPS you get with DX8 or 9 under Windows?
I usually see a lower fps with OpenGL (though I still prefer it)

Fred · Post by **Fred** » Sat Aug 20, 2005 2:12 am

I think it was about the same.

luckymutt · Post by **luckymutt** » Sat Aug 20, 2005 2:40 am

On an AMD Duron 1.6 with 512MB NVIDIA GeForce4 4200, my fps is running between 140-200 with OpenGL and 160-230 with DX9.
I don't have an answer for you, but I just thought I'd throw this in for comparison sake.
What kind of FPS would you think you ought to be at?

afecelis · Post by **afecelis** » Sat Aug 20, 2005 2:55 am

I wouldn't consider 400 fps as low performance.

I'm happy with anything that runs above 30 fps... 60 is heaven!

luckymutt · Post by **luckymutt** » Sat Aug 20, 2005 5:09 am

Yeah with 30frames/60fields per second being the video playback rate, when I see the app I am working on is doing 200 fps, that comforts me to know that I have "room" to keep adding stuff.
Also why I like working on a machine that's a few years old.
If it runs well on this machine, then few people should have a problem with it.

afecelis · Post by **afecelis** » Sat Aug 20, 2005 3:27 pm

I totally agree! It's a great idea to have a high-end and a not-so-new system available for testing purposes.

Fred's pc is a top-notch one, so getting 400 fps is not a surprise. It's the least I would expect from such configuration.

edited:
a real fps performance test would be to run 3dmark 2005 on it to see how it really behaves, and also to check its dx9 performance. That score is a better scale to weigh pc's graphic performance.

Guest · Post by **Guest** » Sat Aug 20, 2005 7:17 pm

Anything above 120 is useless. The human eye does not
notice any difference between 120 and 1200.

Fred · Post by **Fred** » Sat Aug 20, 2005 7:35 pm

I would expect almost twice 400fps when running the terrain demo - I get 600+fps when running other terrain demos.

vgmdev · Post by **vgmdev** » Sat Aug 20, 2005 8:12 pm

Anonymous wrote:Anything above 120 is useless. The human eye does not
notice any difference between 120 and 1200.

Our eyes are too slow under 60fps so you must be wrong?
I think NTSC TV run's on 60 fps.

Guest · Post by **Guest** » Sat Aug 20, 2005 8:19 pm

youre both wrong, our eyes can only see 16fps per second!

luckymutt · Post by **luckymutt** » Sat Aug 20, 2005 8:46 pm

Not sure about the human eye, but film runs at 24 fps, and NTSC tv/video runs at 30 fps(actually 29.97) however that is made up of 60 fields per second.
Thats two fields per frame. Every other scanline creates the "upper field", the other every other scanline creates the "lower field." Together they make one frame.

Fred · Post by **Fred** » Sat Aug 20, 2005 9:28 pm

For some reason under Windows XP, the terrain demo runs at 60fps when I view the terrain and a lot more when I don't view it. This was in DirectX and OpenGL. Maybe my drivers are crap under Windows. Hmm.

Guest · Post by **Guest** » Sat Aug 20, 2005 10:28 pm

The National Televison Standards Committe chose 60hz
not by whim or the pulling of a number from a hat, rather
by conducting studies that showed for the majority of people
" flicker" was minimal at 60hz. Further studies have shown
that at 75hz all "flicker" is eliminated. A good deal of information
and studies are available on line for those wishing to learn more
about this area, that plays a role in modern day graphics
presentation. You may even desire to go a step further and
research the vertical and horizontal blanking periods and their
role and usage in computer graphics. You may even find out
why the color burst signal sits on the back porch of the horizontal.
Or why NTSC interlace scanning uses the even/odd scanning
line method, ie.. all odd lines scanned diagonally, then all even lines
starting from upper left of screen and moving left to right and down.

note: hz is short for hertz, used to represent cycles per second aka fps

Guest · Post by **Guest** » Sat Aug 20, 2005 10:28 pm

LOL!!

you mean if you look at the terrain the fps goes down and if you dont look at it the fps goes up? man, thats not weird, its pure logic!