Say you create a person, monster or robot, with arms, legs, head(s) ... in 3D in a game.

How do you coordinate the body-part movement to achieve the fluidity of real living beings? Is there some theoretical base, or do you just try until it looks good enough?

To put the question in a more precise context, I haven't got some kind of advanced physics engine the would create automatically something physically correct by default.

  • \$\begingroup\$ You don't need a physics engine to create a realistic living's movements. You need a kinesiology engine. As far as I know, there isn't one commercially available which would be suited for inclusion in games (as opposed to medicine and motion picture special effects shops' software). That said: We usually just wing it, and standard techniques like inverse kinematics and quaternion skinning help. ;) \$\endgroup\$ – Martin Sojka Oct 7 '11 at 12:13
  • \$\begingroup\$ Closely related: gamedev.stackexchange.com/questions/6611/…. The tech is only commonly used for solider ragdolls because it's too expensive/unreliable for primary animation, although this is changing quickly. \$\endgroup\$ – user744 Oct 7 '11 at 19:07

A possible solution to animate 3D body models of human-like actors are the rigging and skeletal animation techniques. Usually, these techniques use an skeletal motion that was captures using a MoCap technique, which basically means that the final result will look super natural because the motion data comes from "real data".

You can have a look at CMU's MoCap database, to see the range of human motions that are available, and see if they suit you.

  • \$\begingroup\$ I'd contest your claim that mocap is "usually" used in games - it's super expensive both for infrastructure and actors. I'm also not sure that it looks "super natural" compared to fully hand-tweaked animations; mocap still requires plenty of manual labor from artists to really fit a character in a game, and often the broad strokes from a bad actor will be far worse than the same thing hand-animated by a good artist. \$\endgroup\$ – user744 Oct 7 '11 at 19:11
  • \$\begingroup\$ I'd say it depends pretty much on the kind of game being develop, but it is defenitely used in a few of them. To give an example, MoCap was used to capture footballers playing football in games like FIFA youtube.com/watch?v=QoJfTzR6Vj4 and PES youtube.com/watch?v=MkKJ9h4JKQ4&feature=related Plenty of other videos searching in Youtube for 'games and MoCap' youtube.com/results?search_query=mocap+games&aq=f \$\endgroup\$ – Dan Oct 7 '11 at 22:53
  • \$\begingroup\$ If you think mocap is expensive, you should see the bills for manually doing animations of the same quality =) As for infrastructure you haven't seen the latest systems that even smaller studios can afford to implement in-house, they're a far cry from the old draped stages and ping pong balls taped to everything. \$\endgroup\$ – Patrick Hughes Oct 8 '11 at 1:29

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