Elbow Pinning/Locking

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Old 09 September 2012   #16
Hi there,

I reconstructed my setup and bound it (messily) to some basic geometry.

Stretchy and Pinning switches are on hand controller

Blendtwoattr controls pinning.

BlendColors is the on/off switch for stretchy.

Has global scale, pinning, and stretchy via translation

https://www.dropbox.com/s/duzui6wph...StretchTest.zip

Hopefully you'll find the answer you're looking for...
 
Old 09 September 2012   #17
IN regards to the elbow locking, the clearest tutorial explaining the technique is by far Anmator Friendly Rigging: by jason schliefer.

However, I recently came up with a very interesting approach that got the same elbow locking functionality with no utility nodes and a much cleaner node graph overall.

This is still an experiment so try it out with an open mind and see if it helps at all. It's just the results of some of my studies.

Thi video shows an approach to both the stretch and the elbow locking. Ignore the stretch part, as I was toying around with a way to do it without special nodes or mel. You already have the stretch going so for the elbow lock you can just add on another joint chain for the lock.

The technique:

make another joint chain on top of your IK and stretchy systems. then make a locator and parent it to the IK elbow. Then connect the rotation of the joints for the new elbow lock chain to follow the IK. this will make it bend in the same manner. Then make a Point constraint with maintain offset off from the Ik elbow loc and the pole vector on the Elbow lock elbow joint.

SDK the point constraint to go from either the IK elbow loc or the pole vector. When the Pole vector controls it the snap elbow will lock to the PV.

https://www.youtube.com/watch?v=kF0SUt2bXHQ
 
Old 09 September 2012   #18
Gage - It's good to see your still moving forward with researching your new technique. The extra joint chain seemed to solve your problems with how to pin Now, let's see you add Soft IK to the mix...?

Jared - I downloaded the arm test you created, and have some questions. Right now, when the arm stretches, It's a translate stretch, so it leaves vertices behind that are weighted to the uparm joint, and vertices weighted to the low arm joint move with the stretch 100% obviously causing unwanted deformation and inconsistent stretching. even the best skin weights won't alleviate this, any thoughts?

Also, Your stretch control is a switch, not a blend. any reason why? It really makes it difficult to seamlessly blend between the two states.

I also noticed that stretch needs to be "On" for the locking to work properly. Otherise the joint chain seems to be just normal IK...? seems like the stretch control being a blend would make this a little better. since you could at least animate it blending between.

Last edited by everyFrame : 09 September 2012 at 04:16 PM.
 
Old 09 September 2012   #19
Originally Posted by everyFrame: Jared - I downloaded the arm test you created, and have some questions. Right now, when the arm stretches, It's a translate stretch, so it leaves vertices behind that are weighted to the uparm joint, and vertices weighted to the low arm joint move with the stretch 100% obviously causing unwanted deformation and inconsistent stretching. even the best skin weights won't alleviate this, any thoughts?

Also, Your stretch control is a switch, not a blend. any reason why? It really makes it difficult to seamlessly blend between the two states.

I also noticed that stretch needs to be "On" for the locking to work properly. Otherise the joint chain seems to be just normal IK...? seems like the stretch control being a blend would make this a little better. since you could at least animate it blending between.


Scale stretches cause more issues than they solve. The setup is of course a lot simpler but once you start weighting it's just You're always compensating for the setup.

You blend across frames, no need for an attribute - there was a specific reason but I've long since forgotten it.

The elbow pinning requires stretchy, because for the elbow to snap to that position the arm HAS to stretch. Maybe some other setups are a lot better / more complicated, this is a simple way.

Anyway, main reason I came to post is this:

My pinning setup only works if the PV is moved along the X axis, so if the arms/legs are on an angle it wont snap to the PV, only along the X... annoying, I'll update when/if I have a solution.
 
Old 09 September 2012   #20
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