Ragdoll on alive creatures: has somebody already implemented it?

Question

I find that a dead creature falling realistically is boring.

I wonder, has any game implemented an animation system where the model moves depending of the muscle forces and the velocity of the limbs, but calculated ingame ?

It is much faster to have determinate animation data which is loaded and is just read sequentially, but it looks much "static".

Since I hear a lot about procedural generated data, one could generate a body with its own animation depending of the weight of the bones.

I'm not talking about a real-life robot simulation where the bone is standing, auto-adjusting some angles to keep balance, but something more intermediate and more pre-calculated.

The forces vary slightly between steps (some random on a float so vary plus or minus 10%), so the trajectory of the limbsvary between steps.

It would require a lot of adjustement and preconfiguration, but it would look much less deterministic.

Answer 1

NaturalMotion's Euphoria engine simulates a "motor nervous system" to do procedural animations. It's been used in a couple games, notably GTA4 when pedestrians are hit by cars.

It's still considerably more expensive than static animations, and you'll rarely see more than a few models animated at a time with such a system.

Answer 2

To see this done in an extreme way, check out the game "QWOP", where the player is 100% ragdoll and you use key commands to move the legs.

http://www.foddy.net/Athletics.html

Answer 3

I worked with an engineer who spent an entire year implementing ragdoll support in a AAA game for when a living character gets knocked down. After all of that, they ended up cutting it completely. It was the right decision: it looked horrendously artificial and shattered your suspension of disbelief.

It's hard to underestimate how fantastically sharp our brains our at discerning realistic human behavior and when an animated model steps just outside of that, it's in serious uncanny valley territory. Remember the horror show that was Polar Express?

Answer 4

At lest some of the Unreal games use ragdoll figures, but they are only visual, the game mechanics rely on simple physics.

Answer 5

A fine point to address is the fact that purely ragdoll physics takes far too much realism AWAY from the game, causing players to lose interest easier due to realizing that it is indeed a game, and not feel as if it's another world. On the other hand, you can add lots of realism to a game by using procedural animation techniques based on ragdoll physics. So all I'm really saying, is make sure you know where realism meets comedy, and where to draw the line between what is realistic kinetics and what is just taking ragdoll physics too far.

An easy way to help explain it would be this article I found a long time ago, that describes the ragdoll physics and creation themselves, as opposed to the procedural animation side: PyODE ragdoll physics, a Python and ODE implementation.

I don't quite know an awesome resource for the implementation of the procedural animation myself though, sorry.

Answer 6

You can see if there's any information out on "Die By The Sword," which was all procedural animation, and its successor "Draconus." Also, I believe that "Spore" is all procedural animation.

In any case, it's very CPU intensive and difficult to tune procedural animations which is why you don't see everyone jumping on the bandwagon.