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WIP : Spine with 720 degrees of freedom


sanostol

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Hi, I'm just working on this one.

Right now You can grab the 2 end objects (green circles) and move and rotate them as You wish, and the cubes are solved between them. as long as the twist does not exceed -360 or 360 degrees, it does not jump. as You would expect at 180 degrees.

spine01.mov (h.264)

spine02.mov (h.264)

i want to use it for tentacles or really long necks( dragon) or tails.

still a lot to do but the first steps are done.

Edited by sanostol
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Thank You!

Here is a little update, no anim but i want to use something like this to do some renders, when modeling is finished.

header.jpg

It's impressive how good houdini handles this, I can move the controls in and the rig updates in ( almost) realtime.

I addes some details, the bigger elements won't twist that much so the spine's most flexible part is where it is very thin. just works better with intersections

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Nice indeed.

If you use the Path Tool to build the root curve then use the Bones From Curves tool along with the Bones From Path tool, then you can twist either end and any pathcv's in the middle all you want.

The Path Tool builds up the curve in the traditional way by merging in points from other objects. In the case of the Path tool, it creates pathcv objects and a final path object that merges in the pathcv's. It's the pathcv objects that build the appropriate attributes that ultimately get used by the IK solver in CHOPs to allow you to twist all you want.

You can work in the same attributes in to your existing spine rig setup. That is if you are using the IK solver and bones to do the work.

spine_with_twist.hip

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Doc Oc's arms was one of the inspirations for the support of the twist attributes on curves inside the IK Solver with Solver Type set to "Follow Curve".

There is the Curve Normals parameter on the Inverse Kin CHOP where you can choose different ways to interpolate the twist attributes.

Because the twist attributes are geometry attributes built up from the parented nulls in the spine, you can take your character root and scale it, tumble it, do whatever you want and you get no flipping whatsoever.

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Hi old school,

the pathtool is very cool and works very well, indeed. but I'm not sure what I'm doing wrong but somtimes the chain flips. I'm not sure if I see a pattern, but right now I have a case where I changed the rotation order of one of the cvs to better fit the type of motion I want and as soon as the twist axis overlaps with one other i get flipping. Are there any limitiations to the setup or anything that should be avoided?

Edited by sanostol
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the pathtool is very cool and works very well, indeed. but I'm not sure what I'm doing wrong but somtimes the chain flips. I'm not sure if I see a pattern, but right now I have a case where I changed the rotation order of one of the cvs to better fit the type of motion I want and as soon as the twist axis overlaps with one other i get flipping. Are there any limitiations to the setup or anything that should be avoided?

Offhand, there's also an Initial Twist parameter on the PathCV objects that is automatically setup by the Path tool. You might need to set those up manually if you changed your initial positions manually.

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Doc Oc's arms was one of the inspirations for the support of the twist attributes on curves inside the IK Solver with Solver Type set to "Follow Curve".

hmm I thought it was part of the work to get closer to a true spine (not spline) solver for IK.

still Doc Oc is cool too!

-k

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