Whether the difference is noticable or not, any game that maintains at least 24 FPS is quite playable. One thing that annoys me about some modern games: some games periodically decide to do a lot of memory rearrangement, often involving disk access, causing the display to freeze for 1/4 to 1/2 second. A example of this is Descent 3, which does 60 FPS most of the time, but periodically dips down to 4 FPS. So whatever you do, beware of complex memory management and disk access.

- JRod

Ok, the information i've seen says that-

The human eye cannot see detail above 40 fps
-however-
it can see large movement up to 70fps

i'm sure it varies from person to person sightly but the main
thing you guys are missing is, your eyes don't mind low fps so much as it annoys them to have varying fps. that is why you want to either lock the fps (not a good idea for 3d game) or try to achieve at or above 30 fps at all time...

the constant fps in tv/video and movie are what makes it look smooth...and because of tv's seperate fields the acual fps is only 1/2 of the 24 or 29.97 fps in tv, video and movie. As for your question though...
for 2d animation you can go as low as 12 fps without bugging the heck out of the persons eyes, but in a 3d game where the fps isn't constant try to stay >=30 fps

-mike

btw i don't claim all (if any ) of this information is reliable but is to the best of my knowledge, accurate.

Edited by - thr33d on July 24, 2000 4:02:57 PM

Hmmm...

All this is really interesting, but I wasn''t really trying to match the eyeball refresh rate, or even the monitor refresh rate. What I was trying to get at was a minimum game frame rate - which runs quasi-asynchronously with the others. Agreeably, if you can keep up with the monitor, thats great, but assume for a moment you are targeting a low end Pxxx as your advertised "minimum system" and you have a full 360 flight sim for sale.

Also suppose that testing reveals worst case 8fps on a P133, 12fps on a P233 and 20fps on a P400. Where do you draw the line on a advertised minimum system (I can''t wait to see the answers on this one...).

Personally I''ve found combat sims (like Jane''s USNF) playable down to 10-12fps on my old P90. Below that it''s impossible to target the enemy. Except for quick manuevers, most flight sims have minimal screen motion, so a low fps isn''t really noticed.

A flash of light that is microseconds in duration (not milliseconds, but microseconds) is quite visible to the human eye. I know this because I work with strobing hardware that can provide flashes of light with durations ranging from 15-250 microseconds, and those flashes are quite visible. Now admittedly when those flashes are occuring at extremely high speeds they can blur into a seemingly constant light source (were it not for the fact that each flash results in an audible snap or popping sound, making these units moderately annoying to use, but unavoidable).

I also know that it is quite possible to notice the difference between 60fps and 120fps in a fast paced 3D action game. In particular, performing a quick 180 degree about face in a fraction of a second can make even 60fps too slow for smooth movement as only a few frames are used to render this rather quick motion. At higher frame rates, our eyes will blur those frames together, but they will blur them into a more realistic representation of high speed motion (just as they blur those extremely short duration flashes into a seemingly constant source of light)

And I''d draw the line at 20fps, even for a flight simulator. Unless your game will have NO close range dogfighting, 8-15fps is going to be too slow. As you said, it''d be too slow for close range targetting (which is needed for using chain guns or the like). Min specs should never render any expected game feature unusable (excluding graphical enhancements).

Thanks for the inputs...and, yeah I agree. 20-30 fps is probably a reasonable expectation with today''s technology. I guess I''m a little disappointed with the first cut results, but I''m confident I can tune it up - that''s the fun part, right?

(wimper, choke, sniff...)

BTW, profiling shows about 49% of time in peekmessage() so using Directinput should nearly double my fps - my first target. Curiously, another near 49% is in DirectDrawPrimative (as expected) - but all my AI and scene update processing is only about 2%!