Is it possible....

[AbbA]

Project Gotham 2

The renderer is running at a rock steady 30fps, with the rest of the game (AI, car dynamics, controller input etc) running at 60 Hz, which makes the gameplay is as sharp as it would be at 60 Hz. A solid frame rate is far more important that a high framerate that dips.

Is it possible?

 

[Paul]

Yes, and that's what's going on with the game.

 

[Magnum PI]

Project Gotham 2

The renderer is running at a rock steady 30fps, with the rest of the game (AI, car dynamics, controller input etc) running at 60 Hz, which makes the gameplay is as sharp as it would be at 60 Hz. A solid frame rate is far more important that a high framerate that dips.

Is it possible?

this makes no sense.
why not render at 10 fps while the rest of the game is 60 fps.. it should be as sharp as running at 60 fps framerate too...

of course not.

a solid 60 fps with less eye candy is far more important than a solid 30 fps w/ shiny shine everywhere.

look at burnout 2 its screenshots are not the nicest but playing it is so arcadish, fast.. sense of speed !

 

[notAFanB]

Is it possible?

it's not quite the same.

 

[maskrider]

I don't see why there is a need to process at 60Hz while render at 30Hz, half of the processing will be wasted and the effect will be the same as processing at 30Hz as you process 2 times before rendering a frame but only the 2nd processed result will be rendered.

Don't trade 60fps with shiny shine.

 

[Chris123234]

this makes no sense.
why not render at 10 fps while the rest of the game is 60 fps.. it should be as sharp as running at 60 fps framerate too...

of course not.

a solid 60 fps with less eye candy is far more important than a solid 30 fps w/ shiny shine everywhere.

look at burnout 2 its screenshots are not the nicest but playing it is so arcadish, fast.. sense of speed !

This game is meant to be more of a simulation. If i wanted arcade i would go play San Fancisco Rush.

 

[Qroach]

Is it possible?

Yup, it's possible and lot's of games do things like this.

Now if you're asking the question, are you getting any benefit from the 30/60 approach? well the answer is "yes you are".

30 frames per second on a TV, that means each "Full" frame is shown twice as long compared to a game that is running at 60 fps. That's the catch. On a TV you can't display 60 FULL frames persecond (on a monitor it's possible).

On TV's you can display 60 fields per second (with each field being a half height/interlaced image), so in reality you can see 60 "half" frames per second and your brain blends the two interlaced images together to make a full frame.

That's why it's possible to have 60hz controls when a game is running at 30 frames persecond. At 30 frames persecond you're seeing a frame twice as long as a game running at 60 frames per second.

 

[marconelly!]

Qroach, it has nothing to do with the limitations of the standard TV technology. You CAN have a game running at 60 full frames per second, if you have a progressive scan enabled TV set, and even on a regular set, the difference in smoothness between 30 and 60 FPS game is strikingly obvious. Calculating AI and sampling controls at the higher rate than the visuals are displayed is done because that does allow for greater control precision, though.

Wipeout Fusion, for example, calculates it's AI and samples controls at 120 samples per second, although the game runs at 60FPS.

 

[Blade]

Marc: Was Quincy arguing that framerate doesn't matter? It doesn't look like it to me.

 

[Grall]

I don't know exactly WHAT Quincy was arguing, he's babbling about half-frames and full frames in a way that's not relevant to the subject.

60 half frames per second is circa 240 lines in NTSC. Most modern games draws full frames and then squashes them down through the de-intelacer filter to half frames. The net effect is the same as 60 full frames per second, except the image's less sharp. The brain doesn't merge anything in this case since the image's not interlaced anymore. Think back to 8/16-bit computer and consoles era. They all ran in half-frame mode most of the time.

This has nothing to do with the 30/60Hz update speed asked about in the original post. I'm sure 60Hz AI and input updates have some benefits even when running screen updates at 30fps, but saying it's the same thing is wrong. Latency between input and reaction will be twice as long, and animation on-screen will be juddering quite a bit in comparison.

There's a reason arcade games run at 60fps and not 30...


*G*

 

[marconelly!]

Marc: Was Quincy arguing that framerate doesn't matter? It doesn't look like it to me.

From what I see, he wasn't, nor was I correcting him at that. He was saying that it's the interlaced nature of TV sets that allows for having advantage of calculating the control input at the faster rate than displaying graphics, and that it's impossible to have 60 full frames per second displayed on a TV, and on both accounts that was a wrong assumption.

 

[V3]

Now if you're asking the question, are you getting any benefit from the 30/60 approach? well the answer is "yes you are".

Yes, the more the better, if technology allow you to do 120/120, its even better.

 

[maskrider]

I'm sure 60Hz AI and input updates have some benefits even when running screen updates at 30fps, but saying it's the same thing is wrong. Latency between input and reaction will be twice as long, and animation on-screen will be juddering quite a bit in comparison.

Well, the time between taking a sample and drawing the image determines the latency of the control, you can sample multiple times but only the result right before the rendering will be reflected on the display. I think the control sampling should sync with the display refresh with smart arrangement of sampling time before the image is rendered.

Higher frequency AI and physics processing may be better, but control I think the need is not really that great. But please correct me if I am wrong.

 

[Qroach]

marc

He was saying that it's the interlaced nature of TV sets that allows for having advantage of calculating the control input at the faster rate than displaying graphics

That's not what I was saying! I was giving him an idea of that it IS possible to have a game run 30fps on a TV with 60hz controls. I didn't say the performance of a game is linked to the television. THe game could be rendering at a higher frame rat ethan that, and it would jus tdrop frames. You could sample the controls/physics/AI at whatever rate you want! 240Hz or higher if you have the processor time to spend.

and that it's impossible to have 60 full frames per second displayed on a TV, and on both accounts that was a wrong assumption.

What NTSC analog TV set (you know the kind the majority of people out there have) can display a "full" 60 frames per second, and I'm not talking about some new TV's that can double as monitors btw.

 

[Qroach]

Grall,

60 half frames per second is circa 240 lines in NTSC.

http://www.audiovideo101.com/dictionary/dictionary.asp?dictionaryid=368

"The interlaced video format used by the analog NTSC television standard specifies that two fields create a full frame so that there are 30 frames per second. Each field thus contains 262.5 lines (each line spaced apart by one blank line; all the odd lines are drawn and then all the even lines are drawn in the next field to create a complete frame). When the two fields are combined, the NTSC standard allows for 525 horizontal lines of resolution (although only DVD approaches using those 525 lines with laserdisc using only 425, cable television around 300 and VHS tape just over 200)."

 

[maskrider]

Grall,

60 half frames per second is circa 240 lines in NTSC.

http://www.audiovideo101.com/dictionary/dictionary.asp?dictionaryid=368

"The interlaced video format used by the analog NTSC television standard specifies that two fields create a full frame so that there are 30 frames per second. Each field thus contains 262.5 lines (each line spaced apart by one blank line; all the odd lines are drawn and then all the even lines are drawn in the next field to create a complete frame). When the two fields are combined, the NTSC standard allows for 525 horizontal lines of resolution (although only DVD approaches using those 525 lines with laserdisc using only 425, cable television around 300 and VHS tape just over 200)."

But active lines are max at 483 for the frame (2 fields combined) in the 525 lines, and usually 480 active lines for almost all devices, that will mean usually 240 active lines per field. The other lines are not displayed.

 

[Magnum PI]

This game is meant to be more of a simulation. If i wanted arcade i would go play San Fancisco Rush.

i think having a good framerate is important for simulation too..
simulation does mean more realism, not sluggish game.

i hardly see the advantage of sampling at a rate faster than the feedback the player has. it may have one but pretty limited.

 

[AbbA]

This game is meant to be more of a simulation. If i wanted arcade i would go play San Fancisco Rush.

i think having a good framerate is important for simulation too..
simulation does mean more realism, not sluggish game.

i hardly see the advantage of sampling at a rate faster than the feedback the player has. it may have one but pretty limited.

If you perform more sample x frame, you can reconstruct better the course and the states of the joypad (Shannon's theorem).
This could be the reason to perform more cycles of controls and physics logic, than rendering.

 

[AbbA]

Sloppy physics code can take a lot of CPU cycles. It can take so much time that your frame rate will drop from 60 to 30 frames per seconds or worst. Variable frame rate disturbs a physic simulation and usually, oversampling is used to solve the problem.

Oversampling physics means that the physics code is updated independently from the display. If the game is displayed every other frame (30 fps), physics are still updated 60 times per second. It means that the game runs through the physics code two times before an image is displayed. It helps keep the physics stable.

But wait, if the game has to run the physics code two times before it displays something, then, it eats even more CPU time. And the game can get even slower! And then you might drop to 20 fps and need to update physics three times before you display anything! This chain reaction is a classic problem and trying to get a good, fast 60fps with no oversampling is the best you can ask for. Beware of oversampling and low frame rates.

 

[AbbA]

What about oversampling physics in a Faf racing?