Will someone please explain to me why the cars act in such an unrealistc way when they colide? It seems the single seaters are the only cars without this problem they behace like saloon cars when realy they should be fli[[ing all over teh place when touching wheels . Having stayed away from lfs for a long while this new colision system seems a big step backwords? illepall

i can explain easily: this is wip game and making proper collision system is "a bit" harder than you think.

And let us not forget the never ending mantra : "It is still Alpha... ommm.... It is still Alpha..."

Quote from kevomcenzy :

Having stayed away from lfs for a long while this new colision system seems a big step backwords? illepall

New collision system?, thats a new one to me, its always been pants

Dan,

pants? what? illepall british slang?

Yup, get with the program man

It means "your not kidding ol' chap, it has always been bad, now lets sit down and have a nice cup of tea"

Dan,

As I understand the problem (and i'll willingly be corrected)

The problem is a matter of numerical scale, physics calculations need to be repeated numerous times every screen refresh of the program and the more times you repeat them the more accurate the physics (assuming the basic equation is right).

LFS has a pretty good basic equation, but when extreme circumstances occur such as in a collision the only way to process the result accurately would require many numerous iterations of the physics engine to be accurate.

Therefore one of two solutions presents itself:

A)
As computers get faster Scawen can increase the number of iterations the physics engine does to improve accuracy.

B)
When the game is nearer completion Scawen can jury rig an alternative physics system, a fake system, to cut in during collisions. This would require direct integration with the real physics system and therefor would not be worth coding until the real physics are final.

1. The collisions system has been like this ever since, at least since Im in LFS (1st April 03)
2. The amount of energy is calculated by how far the cars overlap when colliding. Any other method would be really complex. Just remember that LFs calculates the main physics only 100 times a second - this isnt much. When you drive with 300kmh, the car will move 83cm EACH calculation, that is almost one meter.

[EDIT]
beaten by Becky

Quote from Becky Rose :

As I understand the problem (and i'll willingly be corrected)

The problem is a matter of numerical scale, physics calculations need to be repeated numerous times every screen refresh of the program and the more times you repeat them the more accurate the physics (assuming the basic equation is right).

LFS has a pretty good basic equation, but when extreme circumstances occur such as in a collision the only way to process the result accurately would require many numerous iterations of the physics engine to be accurate.

Therefore one of two solutions presents itself:

A)
As computers get faster Scawen can increase the number of iterations the physics engine does to improve accuracy.

B)
When the game is nearer completion Scawen can jury rig an alternative physics system, a fake system, to cut in during collisions. This would require direct integration with the real physics system and therefor would not be worth coding until the real physics are final.

All of that, then chuck lag and latency into the mix and you have a recipe for a nice cake named disaster.

Dan,

Ofcourse driver could just try and hit each other less

even just rubbing the other guy a bit (erm...) is dangerous, ok you're not supposed to but it happens, and when it does it's kinda like having body panels covered in Nitroglycerine, one tap and BOOM! you're over there.

it'd be nice to have different amounts of 'give' for each part of the car. also have you ever noticed how hard it is to cave the door in? it's very difficult to make a side impact mark.

Quote from Theafro :

even just rubbing the other guy a bit (erm...) is dangerous, ok you're not supposed to but it happens, and when it does it's kinda like having body panels covered in Nitroglycerine, one tap and BOOM! you're over there.

it'd be nice to have different amounts of 'give' for each part of the car. also have you ever noticed how hard it is to cave the door in? it's very difficult to make a side impact mark.

That is exagerating a bit :P You can get off with scrubing door handles quite a lot I only find it can become a problem if the car leaning on you is putting a lot of there weight on to you, leaning on your car then it can become a problem, but usually you spin out before that happens

Keiran

Quote from ORION :

2. The amount of energy is calculated by how far the cars overlap when colliding.

A big part of this energy should be "used" in crushing the cars, but it would seem the damage isn't taken into account at all...

I think fixing the collision problems should be quite high on the to-do list, though it seems everyone has sort of gotten used to it and try to even avoid driving "door to door" in the fear of a slight lagspike throwing both cars to orbit.

LFS shows it's damage by bending vertices, these are 3d points in space that the flat surfaces of the 3d object connect too, my guess is the design of the door as a 3d model does not have many vertices in, the design of a door is shaped in one direction only so there probably is not many vertices in the middle of the door, which would make them hard to bend realistically. Adding more vertices would slow down machines, LFS has quite a large poly count already on the cars for low end machines to cope with.

I havn't noticed extreme reactions from rubbing. To be honest I think classes like the TBO (which sadly dont seem popular enough to find an active combo most of the time ) lend themselves to races with lots of rubbing .

IMHO it is hard to "damage" doors because of the driver inside car - it would look stupid when half of driver`s body would go thru the doors. And how do you want to avoid it? In other games its usually avoided by doors "falling off" (which is actually quite unrealistic, because you dont see it often irl), but lfs cant do that yet. Also if you look at the very first pics of lfs damage, you can notice it was much easier to damage the roof

Correct me if im wrong, but havent Scawen said that the damage is just on its begning, and will improve with s2? or am i dreaming?

i think we should not mix damage model issues with collision model issues, i know they are related, but the real problem for collisions is that being granted that collision checks are performed at time intervals, the problem is that Poisson teach us that in such case it is 99.9% (or more) probable that a collision happens in the meantime an thus solid parts will overlap, thus the collision system compensate this situation with an opposite force, the fact is: the solid overlap is an aberration, thus the compensationg force is an aberration too.

the solution to this problem will not be a smaller time interval for collision calculations, but rather a smart handling of the aberration...but we are lucky: Scawen have proved many times to find smart solutions to tough problems...

we only have to hope that collision system is on his todo list for the next major patch

Quote from ORION :

1. The collisions system has been like this ever since, at least since Im in LFS (1st April 03)
2. The amount of energy is calculated by how far the cars overlap when colliding. Any other method would be really complex. Just remember that LFs calculates the main physics only 100 times a second - this isnt much. When you drive with 300kmh, the car will move 83cm EACH calculation, that is almost one meter.

Online you only get 6 packets/sec, so it's even worse, although there might be some interpolation in between.

Difficult to understand is, that a collision is handled differently, one car gets tossed around just like by titanic forces whereas the other driver very often not even realizes that his car was hit (and in fact, his F10 doesn't show any damage).

Quote from danowat :

Yup, get with the program man

It means "your not kidding ol' chap, it has always been bad, now lets sit down and have a nice cup of tea"

Dan,

Rather, jolly good old bean. Tea and crumpets anyone?

The collision might not be perfect, but it does it's job. The simple fix is don't crash into each other.

By the way, nice to see you back Kev

No tea please, lets go racing, "tally ho"...

I think main collision problem is that car can "develop" much greater impact forces now than its actual amount of energy is. Orion said something about overlap when colliding, but it could be checked if amount of energy calculated by overlap dont exceed amount of energy calculated from impact vectors/weights/speeds. I mean, if 2 cars crash at an angle of 5 deg and both with similar speed, microlag can generate overlap and "orbit" forces, but there could be a peace of code calculating max. forces from last known vectors and dont allow exceed this.
Im not game developer, maybe its not so easy..
(sorry for my english)

LFS's collision system looks like it is based on a simple rule: No two objects may intersect at any given time.
That means when two objects intersect because of lag there has to be a force that is so big that by the next calculation step, that means within 100th of a second, a legit state of objects is achieved. That means if a car is stuck 1 meter into a red/white barrier LFS will generate a force that will rocket the car away fast enough so that by the next calculation step the car doesn't intersect anymore. In other words: It is accelerated enough to move 1 meter within a hundreth of a second. That's equals more than 300 km/h (according to Orions calculation far above).

This is obviously a placeholder and should be fixed as soon as possible. Good we're approaching S2 beta.

Vain

Quote from kevomcenzy :

Will someone please explain to me why the cars act in such an unrealistc way when they colide? It seems the single seaters are the only cars without this problem they behace like saloon cars when realy they should be fli[[ing all over teh place when touching wheels . Having stayed away from lfs for a long while this new colision system seems a big step backwords? illepall

Why did you let your collarbone brake, instead of making a cool rollover move? sup kev, wb.

The only time I have had a problem while being close to another car was when there was significant lag, and then their car jumped into mine a bit and I was sent spinning off the track. You can't really help network congestion in a realtime physically based game, I think LFS does an excellent job.