View Full Version : Collision model in Pacific Fighters off a bit?

01-23-2005, 02:32 PM
I just wanted to say that I have noticed while playing back some of my saved tracks, that my Corsair, as well as other aircraft have literally survived flying through enemy aircraft.....

Let me explain.. http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif

On one Offline campaign mission off of Iwo, I dived on a group of Zeroes as they climbed up to meet my flight. When I hit about 400 mph in the dive, I started firing on a pair of zeroes about 1000 feet and closing. Closing very fast I continued to strike the zero, as I watched in facination it's right wingtip shattered, causing the zero to roll uncontrollably. By this time, it was on top of me as I swerved to avoid it's wild contortions and corkscrews through the sky.

I was amazed how close I got to him, but didn't collide!! I noticed I didn't have the control of my corsair as I had before, but continued the mission. I found out after I landed and reviewed the track that the Zero tore off my left horizontal stabaliser!!

So I saved the track, and went through to where this amazing incident took place. When I put it in slow motion, and paused to see what was happening, I found the Zero's Propeller disc should have collided with my engine hub, it's fuselage went through my entire left wing, but the only damage I got was when it hit my left horizontal stabalizer and peeled it off of my plane.

I never should have survived that mission, I would really like to see this fixed if it's possible to do so. I have tracks saved of multiple incidents of this happening and hope that something could be done about it. I would like to propose that the propeller disc should be considered in the collision, as well as other parts of the plane. I don't know why this is happening, but I really hope it will be fixed in a future patch. http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif It's not fun being a semi-transparent ghost plane when you do head-on attacks http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif

01-23-2005, 02:41 PM
It's just got to do with lag and packet loss.

01-23-2005, 02:48 PM
But I only play offline... http://forums.ubi.com/groupee_common/emoticons/icon_biggrin.gif

Using the DGen. I didn't think there were any packets to loose when your playing offline.

01-23-2005, 04:06 PM
^ There isn't..and you are right.

In QMB, I've flown through planes literally..with no damage effect. It doesn't happen very often at all but it's there.

Online is an entirely different matter; it's not unusual (as Tom Jones said) to be 100m away from another plane and to 'hit it'; whether it's packet loss or not is difficult to verify.


01-23-2005, 04:13 PM
Thanks for the response Norris and Rall. So apparently this situation is amplified online where packet loss is a factor?

It also seems to only happen with a very high closing speed. The slower the collision is, it seems it's more accurate. The faster the planes collide, the better the chance of something passing though the other object without any effect.

At any rate, I hope something can be done to fix it, and it seems I'm not the only one to experience this, thanks for your input guys http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif

01-23-2005, 04:22 PM
It's all wrong, but it's no worse than any other sim.

Usually an artifact of packet loss, but also by probably a lack of well-defined (i.e. long) code, what it likely lacks is AGREEMENT. The concept that both planes have to "agree" that there has been a collision, what parts are involved, and then apply the proper amount of damage is really done a disservice online by packet loss and lag (about which little can really be done). Online, it's entirely possible that one person sees the collision, and the other sees a miss. So, one plane flies (completely untouched, no less!!) and the other one suffers catastropic damage or even explodes. Downright stupid and unsatisfying result. To my mind, with the speed that things happen, there is time for a few rounds of "agreement checking" among the various front ends to determine IF both players' software "saw" the collision. If both don't, it shouldn't have happened. Give the planes the benefit of the doubt and let the guns decide things. If they do agree, well, then, both sides HAVE to take some damage.

Even if there were a one, two second or so delay between a "near miss" and having a wing or two rip off or a sudden black screen of death, it would be much more satisfying than having YOUR wing fall off, and the other plane fly off as if NOTHING WHATSOEVER had happened to him.

While it is important for a faster attacking plane to control his closure, I still have suffered many "collisions" where the "victim" saw me at the last minute and just splayed his plane out in a last-ditch barrel roll, snap roll or attempted break turn, and then *I* somehow contact him as I'm pulling off and away.

I even had one case, during a Bellum War scenario where I somehow ran my prop into the bottom of a badly wounded Hurricane that was trying to avoid the coup de grace, and had pulled up and rolled over the top of me in an attempted scissors. My engine "just stops" and he flies off with no further damage to his crate, which is full of holes in the wing and fuse. No justice.

01-23-2005, 08:39 PM
Obviously they could improve certain aspects of the DM but in comparison to any other WW2 sim its a dream, most other sims if you fly anywhere within the hit bubble you will both automatically be destroyed, I would rather what we have now than going back to hit bubbles.
I've had experiences where even online Ive had a plane brush my wing and both of us survive Ive also had the wing clip the ground lightly bounce up and the plane survived, I think a lot of the problem is to do with processing power as much as bad code but either way this sim models it better than any other that Ive played.

01-24-2005, 09:46 AM
I have seen this happen too. Usually when passing through the wing of a bomber and touching with the propeler. I always assumed that I chopped them up and was plain lucky to have the engine running.

01-24-2005, 03:34 PM
Thanks for the responses guys, so basically the consensus is that others have seen this, but it's better than the alternative. http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif

I can live with that I guess. I'm sure Oleg knows about this as well but perhaps he'll find a way to improve upon his work even more, both for the onliners and the offliners

By the way, Stiglr, I don't know how you guys play online, from the stories you gave me with the collisions and lag or packet loss that would drive me nuts! http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif

01-24-2005, 03:41 PM
That is not so simple guys. It is not a bug. Is alimitation on discreete physics summulations. When you run a collision detection algorithm with two very fast moving objects there is a chance that objects would cross between two frames.. but would nto intersect at any given frame. In this situation collision detection can still be made, but becomes much more complicated.

01-24-2005, 09:24 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by AlmightyTallest:
from the stories you gave me with the collisions and lag or packet loss that would drive me nuts! http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif <HR></BLOCKQUOTE>
oh it does , especially when you having a good fight & then you get "shot down" & your fellow collidee flys away

& its been a part of FB since v1.0

01-25-2005, 09:39 AM
How many times a second you want collision to be checked, for every plane?
Figure out how many meters you both move in one second and then divide.
Does the check routine model curves, rolls, etc?
Like everything else, it could be more or less accurate/detailed/complete.
But what else will gain or suffer?

There is an overall amount of detail and speed for everything and check the
posts since day 1 of IL2... too many people only know the word "more".
I think we lose some things... no, I know we lost some things.

01-25-2005, 10:38 AM
I'm not saying I want collision checked for every plane every nth second.

My idea (and the caveat is, I don't know if it is workable, it just seems to me it should be) is that IF a front end sees a collision, the sim knows what it supposedly collides with. So, before it applies the result, just like with gunfire, it can "communicate" with the other FE to see if that FE also detects a collision.

It's situation dependent, not ongoing, like overall positioning.

01-25-2005, 01:18 PM
That's a game call and I think we've both seen both sides of how it can work.
Like... with lag when you don't even get really close and suddenly "boom"!

People say there is no lag offline but really nothing is simultaneous (but I did
bug Oleg to please set the code up to spread the AI's out on a LAN if the player
or server has one!) so there's small but real lag even offline. Even framerate
is a for of lag measure but what are the chances that control inputs are done at
the same rate and lower priority... collision.

Well, you're not supposed to get too close anyway. Full zoom is how the view would
look IRL, IIUC, and see how close you think of getting at full zoom! Zoomed out is
like what, 1/4 size? Easy to let yourself get too close.