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Stashed bodies moving on their own


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Something I've noticed playing No Honor Among Thieves - I knock someone out and stash their body nicely in a dark corner. I run around the rest of the map and maybe quicksave/load a few times, but when I come back through the area, their bodies are back out in the middle of the floor.

 

I'd say I just forgot and loaded a save where I hadn't stashed them, but it happened with almost every person I knocked out. Sometimes it seemed like they were in the position where I knocked them out, or just somewhere on the way to their final destination.

 

Has anyone else noticed this? I did a search and didn't come up with anything, but I wasn't even getting close to the same results so its likely been discussed. It wasn't a gameplay issue, but had the area not been dark enough already and an AI pathed through the area, it could have turned out badly.

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I'm having similar "anomalies" in my game. Bodies that I've KO'd or killed will twitch/slide along a surface and won't stop. I finally just accepted it, thinking it was a (bad) design of the game. I hope it's patch/problem that can be fixed, as it's very weird. Not to mention that if the game is constantly calculating physics on stuff like this, it's got to be robbing the game of performance.

 

I'm running D3 through Steam. It should be patched to the latest version, right? I'm willing to test some things. Where should I start?

 

{Going to work today; can fiddle with it tonight, maybe.}

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I remember seeing that in one or two particular maps (Heart was one) but not as a general rule.

 

odies that I've KO'd or killed will twitch/slide along a surface and won't stop.

 

This can happen if they're on a slope (AI bodies have unrealistically low friction to allow the player to drag them more easily, but it results in them sliding down slopes that the shouldn't). If they're jumping and twitching, then it's more likely some attachment is getting in the way of the ragdoll. That shouldn't happen as a general rule, but might if a mapper has bound something to the AI.

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I'm running TDM 1.05. I just installed it in the last week.

 

It may be in the map, I wasn't sure. I'll keep an eye out in other missions and see if its a recurring thing, if it is I'll bring it up again.

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This happened to me in The Heart of Lone Salvation and in The Alchemist

TDM v1.05

 

Seems to affect stacks of bodies. When I returned to my body stacks, near the end of the mission, my stacks were gone. Bodies were scattered nearby, twisted into human pretzels. Quite funny really. I dont recall any unstacked bodies which were affected.

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Stacking bodies sounds like the likely culprit given a ragdoll is just a large collection of constrained physics objects. The way I understand the physics engine is that once the movement of an object falls below a certain threshold the object is considered at rest and calculations are skipped. But if the threshold isn't high enough you could very well end up with a sort of perpetual motion machine where collisions cause ejections which lead to more collisions and so on. Objects never come to rest because constraints keep all the colliding objects relatively close to one another.

 

This is all conjecture pieced together from discussions I've seen on D3W by the way. I've never looked over the SDK as I don't think of myself as a competent coder.

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LOL...

 

Even John Carmack himself mistrusted the Ragdoll physics team and they struggled dearly with that portion of the code almost up till the release...

Please visit TDM's IndieDB site and help promote the mod:

 

http://www.indiedb.com/mods/the-dark-mod

 

(Yeah, shameless promotion... but traffic is traffic folks...)

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I wonder how hitman blood money did it. Seems stable enough there.

 

They licensed Havok Physics for that game... (A whole company dedicated to building physics engines for games.)

 

Id Software used a small in-house team...

 

Edit:

 

Not to put-down what's there, just saying that the challenges of fixing the SDK physics are not necessarily trivial and improvements should receive proper respect... ^_^

Edited by nbohr1more

Please visit TDM's IndieDB site and help promote the mod:

 

http://www.indiedb.com/mods/the-dark-mod

 

(Yeah, shameless promotion... but traffic is traffic folks...)

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Cool. I am also think of another impressive thing that game did that could maybe be copied:

The crowds on the parade level - it seems like something feasible if you have 3 ingredients:

1) control the complexity of models, intanciating them, lower complexity at distance

2) have a ai system flexible enough to adopt a flock model movement scheme so you can then:

3) turn off collisions and most AI specializations.

 

It was a really neat effect seeing dozens of npcs at once.

Edited by i30817
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Yeah, there has been some talk of making Ambient AI.

 

For big crowds???

 

I see the SEED system spawning func_animate objects as possibility (if anyone can figure out func_animate, or figure out how to make SEED produce 3D distribution patterns)... but I still think it might be a little too heavy on the target hardware...???

Edited by nbohr1more

Please visit TDM's IndieDB site and help promote the mod:

 

http://www.indiedb.com/mods/the-dark-mod

 

(Yeah, shameless promotion... but traffic is traffic folks...)

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They licensed Havok Physics for that game... (A whole company dedicated to building physics engines for games.)

 

Id Software used a small in-house team...

 

Edit:

 

Not to put-down what's there, just saying that the challenges of fixing the SDK physics are not necessarily trivial and improvements should receive proper respect... ^_^

It isn't in the wiki list http://en.wikipedia...._in_video_games

 

Edit: heh. here are people complaining about it:

http://www.hitmanfor...-money-physics/

 

specially look at complaint 2.

 

Also look at the bullshit starting on the bullet forums about software patents

 

http://bulletphysics...wforum.php?f=22

 

Erwin,

 

If you were to meet the devs responsible for the patent application in a bar in Dublin over a glass of Guinness, they'd probably tell you, off the record, that they get paid a bonus for every patent app and more if/when the patent is granted. It's part of corporate 'legal marketing'; 'we have n physics related patents', used to promote the company for investors as well as defend against competitor legal action. It's true that many patents can be invalidated by prior art, but as EK noted, (any/all) litigation is expensive, and lawyer time to research each patent and try to invalidate the claims costs money. Having many, effectively worthless patents has value as time and money must be spent for invalidation: kind of like disposable armor.

 

The physics related patent claims that I have read are so complicated, and have so many detailed claims; it is relatively simple to work around the claims. I would not worry about getting a suit filed against the Bullet project: with so many developers aware of the source code and prior art, the public/media effects would be costly for the litigator. Additionally, if the prior art is clear and obvious, help is likely available at no cost via the FSF and similar organizations.

 

My experience with patent litigation and the legal system in general is that the system itself is quite simple compared to writing real-time physics software. Patent claims are simple Boolean algebra- easy to understand as a form of basic math (even Markush claims), and legal process is also relatively simple: file the proper papers with the proper format and go to the next level. For a software developer with no experience in this area, it can appear daunting. Honest lawyers ( icon_wink.gif ) will tell you that their job is really pretty easy, it just takes time to do the research and file the papers, correctly formatted and on time. Their experience in knowing what is important, and where to focus time is what can justify their high cost.

 

Since my physics tech is closed source, and I have published the major concepts which I believe someone might try to patent, I'm not worried about a software patent suit. Additionally, the aggressive party won't just hit a software developer with a suit; they'll first send a letter claiming infringement, to which you can respond. If you respond with clear, obvious, incontrovertible proof of prior art, the issue could go away, and never become public. If they press the issue, you can make it public, and ask for community support. I would certainly help in such a case. Another option would be to change your code slightly so that the aggressor no longer believes you are infringing (even if you have proof of prior art): take the path of least resistance. The most likely patent actions will be between Havok, Ageia, nVidia, and AMD. Small devs and open source projects won't likely even be a blip on their radar, unless it somehow costs them money, or makes their competitor(s) money.

 

The patent system is a form of business warfare. Arm yourself with knowledge and don?t be intimidated. The absolute worst case scenario is you?d have to change or remove a piece of code from your library. There?s always another way to solve the problem, especially since fundamental (broad) patent claims aren?t being issued for physics technology (a ?one-click? type patent claim in the physics space would be hard to get pushed through the PTO; if someone did manage to come up with something broad and simple, with no prior art, all the power to them for getting a patent and protecting it).

 

See what the bought for USSC has wrought. Filthy lawyers POS.

Edited by i30817
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Also if you care.

http://bulletphysics.org/Bullet/phpBB3/viewtopic.php?f=22&t=208

Quote:I recently looked at the Doom3 SDK source and they seem to have an impulse based formulation as well as a LCP solver. I have not enough knowledge or experience with LCP solvers to recognize the kind of the solver. Do they use a GS or similar method or is this already a more advanced solver that is superior to the GS in the context of computer games?

 

A few years ago, Jan Paul van Waveren (idSoftware's Doom3 physics programmer) told me he used impulse-based method for contacts and an LCP solver for ragdolls (non-contact joints). Probably he uses a direct /pivoting LCP method.

 

I'll ask if he can explain here on the forum.

 

It is typical to mix a direct LCP solver with iterative method. Especially high speed Ragdolls don't behave well on impact, their limbs detach. Typical scenario is a high speed car against a pedestrian, or a character standing next to a barrel (explosion). I've seen this in a game I worked on in the past, and we used Featherstone for the ragdolls, and impulse based for contacts.

 

Erwin

Edited by i30817
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well in real life bodies carry on working for at least 36 hrs after someone is claimed to be brain dead. And some body's do do a lot of twitching after they're dead, its just not reported much, so the ragdolls in doom 3 are in one way more realistic to real life than suddenly stop moving game dead. And you can move limbs around in tdm ragdolls, just pick up the limb and move it. Although I did find on the idsoftware site a script command to make the ragdolls become AI again, something like 'stopRagdoll'

 

At least the ragdolls dont end up in the strange position like they did in thief 3, on their knees and arched over backwards.

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