[ODE] Can't edit the Wiki
russ at q12.org
Tue Mar 15 12:59:51 MST 2005
there's wiki-editing instructions on the main page at
"Please login first using the <page> and use the password
'sesame' if you want to make edits.
everyone has wiki-editing access, you just have to type 'sesame' into the
On Tue, 15 Mar 2005, Jon Watte wrote:
> I can't add anything to the Wiki, so please someone with access
> add the following text to tips-and-tricks:
> How to turn an animation into dynamics forces:
> I'm assuming a rigid skeleton with ball joints, but you can
> generalize to any kind of joint that your animation uses:
> For each frame, pose your animation skeleton the way the
> animation wants it for the NEXT frame in time.
> Then, for each body in your dynamics skeleton, measure the
> angle relative to its parent, and compare to the animation
> skeleton. This gives an angle error in parent-relative space
> for each bone.
> Now, calculate the torque necessary to move the body to the
> desired angle in the next timestep (or in some amount of
> future time, of you want a more dampened fit). Optionally
> apply maximum joint torque constraints. Apply this torque to
> the body. Step the world. Yay, you're done!
> For position constraints, substitute "movement" and "force"
> for "angle" and "torque".
> If you want to support external forces like holding things,
> you should also keep an error accumulator, and add in some
> multiplied factor of that error to your force, so that you
> will compensate for being off in a specific direction for
> many steps.
> / h+
> "Unix and C are the ultimate computer viruses."
> -- Richard Gabriel
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