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Slow slow slow

Started by q2guy Oct 12, 2005 at 1:31 PM 8 replies 1.7k views
Original Post
q2guy
q2guy
I have been playing with several physic systems, and with my simple physic engine (only a plane and boxes as rigid bodies). When I see the simulation in all systems, I see that all bodies moves slow (no graphics problem). In reality, if I catch a pencil, and I let fall it from 1 meter for example, the sensation of falling object is that it goes to the ground very fast, if I try to do the same in a physic system, the result is a slow falling, that for me seems unrealistic, no one see it in this way ?? I need glasses ? xD I see in reality all is fast, movements of human body, objects going down, ... why in games for example, they don't try to get this real looking ? is there any way of get this results, without cheating the physic engine with extra forces, that don't exists in real world ?
oliii
oliii
Yeah, I would agree on that. Somehow, computer sims feel slower than they should be. It's not uncommon that in games, gravity is pushed up or some time acceleration factored in to give a more sense of speed (and grip, for arcade car sims). In fact, dropping a pencil should feel faster on a computer, since forces, like air drag, are neglected.

But if you time it, and time real world values, you'll find that they match. Also, you have to be careful with things like scales. For a pencil, you'd have to make it 1/2 foot.

There are other cues, like motion blur, and stereo vision, which gives a better sense of scale and speed. Field of view is also much greater, but I don't know how much physicoligical factors like that actually influence the sensation of speed.
Everything is better with Metal.
frob
frob
I think Oliii is right, but in the reverse order. Also, he didn't mention The Fun Factor (tm).

I'd say that the biggest killer is all the games with messed-up physics conditioning us. We are so used to seeing the bad physics, bigger gravity and cartoonish-effects that we have come to expect them.

Visual cues and comparative speeds are important, although The Fun Factor means you often have to discard reality for that.

FOV and scale just enhance the 'problems'. Many games just pick a scale that happens to look good in their modeling programs. They'll play with a physics engine until it looks good. They don't care about having a physically-based world, just a fun one that fits their story presentation.

The bad physics isn't necessarily a bad thing.

It's often a good thing that we don't do everything with actual real-world physics. It's much more playable to use sped-up or slowed-down physics.

I really don't want a flight simulator to go through a half hour of pre-launch, three minutes of launch, an hour of boring flight toward the target, drop some bombs, an hour flying back, etc. Even with an auto-pilot to quickly jump between locations, it still doesn't make the game fun.

Contrarywise, things that explode, are jumping, thrown, or shot tend to move too quickly in the real-world physics, and the game is more entertaining if they are slowed down. It's fun to watch your tank lob an oversized shell in the air, where it moves slower than it would in real life toward your opponent, and watch them explode in a larger-than-life fireball, rather than the small dents their tank would likely experience.

frob.
joltios
joltios
I give example to last post: Battlecruiser millenium. It is space ship simulation which takes a lot of time.
q2guy
q2guy
In actual films, there are two ways the effects are made, one is the matrix like, where time seems to stop, and other where the suddently an violents explosions, fast movements and fast camera leads all the action. The last style is used for reality-like, and the first for fiction.

What I'm talking is to get a physic engine tweak, where the tweak is not tweak, is a real-correct physics solution, to make fast things like they are in reality. And I want to know if this is possible without using visual cues like oliii suggested.
frob
frob
If you're looking to compress or decompress the presented time but still keep the physics accurate, just pass different time step values to the physics engine. All the engines I'm familiar with support that sort of thing.

frob.
MrRowl
MrRowl
Incidently, it's possible that your computer is a bit screwed up and everything IS actually running slow on your computer! I exchanged a couple of emails recently with a guy who uses my flight sim and had to put a "time-scale" parameter in for him to make it run about 1.4 times faster, and he has the same problem with other apps too (he checked with a stopwatch against a known time-interval reported by the program).

I suggest you time some things by hand - "drop" a ball in a simulator from 100m up with gravity 10m/s/s and get the computer to emit a signal when it starts and when it lands - check against a stopwatch and whatever number you come up with on the back of the nearest envelope.

arpion
arpion
The physics engine looks slow just because the the bodies in their demo are large size. for example, if you add a box with the size 1, it corresponded a box with 1 meter size in the real world, when you drop it from 10 meters high and look it from 20 meters hight, it look slow too. the same, if you add a box with 0.1 size in the physics engine, it will looks fast now, like you drop a pencil. These are because the g is always 9.8 . change the g value can also make it looks fast.
frob
frob
Quote:
Original post by MrRowl
Incidently, it's possible that your computer is a bit screwed up and everything IS actually running slow on your computer! I exchanged a couple of emails recently with a guy who uses my flight sim and had to put a "time-scale" parameter in for him to make it run about 1.4 times faster, and he has the same problem with other apps too (he checked with a stopwatch against a known time-interval reported by the program).


That could easily be the case of inaccurate timers. See this article on PC timers written by hplus.

frob.

sbroumley
sbroumley
Out of curiosity, how do you get at the system clock time on a PC? Surely that doesn't go out of sync with real time?
Steve Broumley

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