Help on Strategy for Animating
GregBollella last edited by Dr. Sassi
I'm trying to animate a starfish-like creature. I'd like it in the xy plane and rolling and moving in the -x direction while the legs alternately reach out forward, touch a stationary object, then retract.
I've tried with joints but IK alone isn't sufficient (because I cannot extend the leg). FK allows me to extend the leg nicely by keying the distance between each leg joint larger and smaller but this is only in a straight line and I would like the leg to curve as it extends.
I am currently trying the following: Separate each leg into its own object. Use an FFD to get the extended shape. Then a PoseMorph tag and animate the strength. So far this seems best.
Before I commit to the PoseMorph tag option I'd like any suggestions about other options.
Here's a link to a file with the PoseMorph solution for one leg to better explain the motion I'd like.
With the legs and body separated, the Spline deformer is excluded. The Spline IK would work, but with the considerable stretch you like to have, the "twisting" might come quickly and can destroy the whole thing.
Having a dense mesh creates some problems with animating. Typically, each point needs to be weighted. A workaround is the Mesh-Deformer. I have set up here a simple one as a demo.
The Few Joints needed are then easily animated with a PoseMorph or even manually with keyframes. Perhaps even with an Animation Clip.
I have pulled from the Skin Deformer> Object> Length. Here you can select how the shape is conserved or changed.
All Joints are set up and then, via Freeze, placed into a zero position so that you can reset the rig easily.
All the best
The separate legs were only so that I could use the FFD (not sure how to use it on a partial object).
After understanding your construction I got rid of my original mesh, scaled the points of the legs in (to make them thinner, added a subdiv and did current-state-to-object, re-bound the new mesh, and checked the animation. It looked very good.
So, now, a simpler solution with great deformation.
Thanks a lot, Greg,
That is nice to hear! It sounds like you get it working for you. Thanks for the feedback.
Tiny details can be added via the Displacement of Normal Maps. I assume nothing new to you, but as usual, I write in a forum and over share.
Let me know if there is something else; I'm happy to look into it.
My best wishes for your project
@Dr-Sassi Ultimately, I went with a PoseMorph tag and FFDs. I tried IK splines and they were reasonably ok but getting the mesh to stretch as much as I wanted was difficult and to get the tentacle to bend nicely I had to keyframe each joint. Using pose morphs and ffds was more straightforward. I made the base pose with tentacles very short and high, regular polys, then simply scaled from the base of the tentacle to stretch it out into the ffd then manipulated with the ffd into the shape I wanted.
Here's the resulting video.
Dr. Sassi last edited by Dr. Sassi
Thanks for sharing. There are always many ways to get there; the key is choosing what fits you best.
Here is a quick demo of what is possible just by converting a Spline to Joints, binding it with an object, and using the Pose Morph for rotating the Joints and the Parameter of the Joint Length (Hierarchy is on as well).
The key is to select all Joints (Select Children) and place a value into the parameter that needs to be changed. This can also be done with num*2 in the rotation field (num is the selection index, whereby 2 is just a number [degree here]).
This can be improved with some weigh-smoothing, again, just a sketch.
@Dr-Sassi WOW! That's beautiful!!!!!
Thanks so much !!!!!
Thanks a lot, Greg, for the kind feedback.
You're very welcome.