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SPENEN
03-11-2003, 12:42 PM
Hi there =)

I was playing with bones in maya yesterday and I got an idea.
Wouldn't it be cool if I had a skeleton, and then just added som limits to the bones and applyed a gravity to it. THen it could just fall dead, or maybe an better example, fall down from a hill =).

It should be possible, but i just dont know how =/, I can make the bones to be applyed to a gravity and bounc ,but not so that they keep the distance. May be it could work with a point constrain, but I havn't managed it =/

Thx in advance =)

,.-'`SPENENī'-.,

Rudity
03-11-2003, 02:13 PM
Ive thought of this too, but personally id rather animate the character falling down the hill. Man that would be a fun shot.

IkSplines would work, you can throw deformers, dynamics, fields etc etc on the curve.
Though you wouldn't have much control, and to me that sucks.
I like having control, so I could make him smash is face on a rock while his back bends the wrong way and his feet arch back and kick his face harder into the rock...

Man I wanna animate that, heheheh fun fun

later

SPENEN
03-12-2003, 09:47 AM
Yes you are totaly right that its the best to hand animate it.
But ofr example in starwars episode 1, when all the druids dies =D, thats my nightmare to ghand animate, maybe they animated a few and then copied it, but anyway =).
THx for the answer, i'll try that today =)

,.-'`SPENENī'-.,

Octagon
03-12-2003, 11:01 PM
Originally posted by SPENEN
Hi there =)

I was playing with bones in maya yesterday and I got an idea.
Wouldn't it be cool if I had a skeleton, and then just added som limits to the bones and applyed a gravity to it. THen it could just fall dead, or maybe an better example, fall down from a hill =).

It should be possible, but i just dont know how =/, I can make the bones to be applyed to a gravity and bounc ,but not so that they keep the distance. May be it could work with a point constrain, but I havn't managed it =/

Thx in advance =)

,.-'`SPENENī'-.,

Good question. I'm more of a particles guy but I hope I can at least make some good guesses about how this could work ;)

Putting limits on the bones only works for ik. So, unless you have a simulation that drives ik handles that drive the skeleton thereafter joint limits won't work.

But try putting rigid body objects in the skeleton hierarchy and see what happens when you run a simulation. You need to build some proxy geometry to give the rigid solver something to calculate collisions with (use simple objects like cubes and sphere for all arms, legs etc.)

If the rigid bodies don't stick to their hierarchical placement in the character (i'm not sure how rigid bodies and hierarchies interact really) you would need to built a separate skeleton out of rigid bodies.
Use constraints etc. to bind the real skeleton to the simulated rigid body skeleton.

Hope this helps.
matthias

SPENEN
03-13-2003, 12:31 PM
The thing that is the hard bit is the limitations, if I make a rigid body skeleton it can't have any limitations, but it can if it's a skeleton. Hard to combine those =D. I'll tell u guys if I succed =)

wrend
03-14-2003, 12:18 AM
rigid body constraints to build your structural/~hierachical relations.

bigfatMELon
03-20-2003, 08:41 AM
The thing to do here is to build simple standin objects to use for the rigid dynamics. Limit them by building the limits into their shapes (joint sockets). Dampen them by adding springs along their length (muscles). Then constrain an alternate input skeleton to these shapes.

The only real trick to all of this, besides making good collision shapes, is setting up the initial position and orientation of your collision objects prior to switching over to the dynamics skeleton.

-jl

Octagon
03-20-2003, 11:56 PM
Originally posted by bigfatMELon
The thing to do here is to build simple standin objects to use for the rigid dynamics. Limit them by building the limits into their shapes (joint sockets).
-jl

sounds good. but i dont understand your approach for limiting. could you elaborate?

i mean, there's a lot of attributes on joints and even transform nodes for limiting motion. but i was under the impression that limiting would not would in all cases for all sources of inputs to, say translate values. i guess it could use setAttr to give joints or at least transform nodes values that are outside the lower/upper limit boundaries.

matthias

bigfatMELon
03-21-2003, 05:44 AM
A human leg isn't limited by parameters in the leg that an animator sets numerically. It's limited by things like legaments, muscles and bone interactions. So, model physical polygonal objects that are shaped such that their limits are implied by their own shapes physical interaction.

A shoulder joint, for instance, could physically limited when the end of it collides with a collar bone or rig cage object. Springs can be used like muscles, causing the shapes to want to return to certain orientations or drag at certain extremes.

-jl

Octagon
03-22-2003, 12:54 PM
thx! Now it's clear.

When you said about implementing the limits in the shapes I immediately tought about shape _nodes_ in maya.

Man, maya makes you look at everything as a node or object when you spend to much time in front of it, I guess ;)

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