Best way to rig breasts?

foxpawmcfly

(For the sake of keeping this "safe for work" I will be referring to breasts as "Water Filled Balloons", both in text and visual diagrams).

Needed: Simple, effective rig technique for a "Water Filled Balloon" that is anchored at one point.

Pendulum, anchored at one point, able to sway with follow-through momentum / secondary motion
Squash/stretch, similar to a rubber ball- but not as rigid, allowing parts of the object to deform more than others, like resting on a table or pressed against a wall.
Potential IK? If the anchor point of the pendulous object has an IK handle at the other end, allowing it to rest on a table and squash that way?

A. I have over a decade of experience with Flash animation, and have taken into courses to 3D animation, but I just installed Spine Pro 2 days ago, and have been following tutorials for rigging. They have gone well so far, and I am catching on fairly quickly, but all the squash stretch stuff I have seen around involve complex IK setups that don't really yield the right results; Or the "ball with tail" tutorial Spine released officially, which shows how to make a rigid ball, but not one with the physics that would work for a water filled balloon.

B. I tried the complex way first, mapping out mesh points around the balloon to make sure it deforms well. But weighting a bone or two to handle the squash and deformation didn't turn out well, no matter how many or few bones I used, or how I distributed the weights.

C. I tried using a 2-bone IK to make the squash against a solid object work, but that turned out terrible. And a 1 bone IK with a target point didn't work either.

D. I went back and tried just simplifying the balloon to a 4-corner-point mesh with a single anchor bone. But this is no better than Flash CS6, a flat object skewing/scaling/rotating. I tried 4x4 to make it a bit better, but still not great.

E. Currently, the best I can do is my original well defined mesh around the balloon (maybe a 5x5 grid, curved to the contours of the object), with one bone for the anchor to keep the attachment point still, and one bone down the axis of the balloon to pose it....

Is "E" my best option? Are there any other good tutorials for squash/stretch rigging for beginners?
Is there a good way to take "E" and apply an IK down the axis of the balloon so that single point can control the deformation of the image?

Misaki

foxpawmcfly If the "shape" of the breasts needs to be significantly changed, I think the method suggested by skarasuko is the way to go.

In general, the rig for breasts is often sufficient if the breats can simply sway, in which case people often use weights to make the protruding part of the breasts move. I have an example of a bust rig I made to explain to someone once and you can see my example in the video below:

I show the Graph view at the end of the video because I would like to show that the X and Y translate timings of the bone for the breasts control were shifted. By doing this, the bones move in an elliptical trajectory, which makes the movement more natural.

I hope this will help you.

skarasuko

I have an animated example I can show.

For my personal objectives, I use 20 bones that are in a Path Constraint (Proportional Spacing 100, Chain Scale Rotation) and weight them to the image, so that I am able to manually shape the image with the path points if needed. To achieve the squash and stretch I have only a few constraints (2 per bone) to set up:

IK Constraint: Create a "reference" bone that is equivalently created as the "primary" bone. Note, the reference bone cannot be parented under it. IK the reference bone to a new "target" bone. In Options, checkmark everything (Compress, Stretch, Uniform)
Transform Constraint: With the primary bone, have it target the reference bone. While working in Animate mode, adjust the TC Mix to your preference. The general rule here is: + Rotate, + Scale X, - Scale Y.

foxpawmcfly

Misaki This is pretty much what I need for my approach, but I don't see bones just those "+" symbols, attached and weighted to the middle of he image. Are they added the same way bones are added, or are they different? Maybe I don't understand the way bones work... I may need to experiment more. Thanks for the help

Misaki

foxpawmcfly

but I don't see bones just those "+" symbols,

Ah, that is actually where beginners often get confused! The "+" symbol is just one of the options of the icon for bones, the function itself is exactly the same as the normal bone. See the "Icon" section of Spine User Guide on how to change the bone's icon: http://esotericsoftware.com/spine-bones#Icon

warmanw

Some experiments. let me know if this works for you.

newbie2024

warmanw sorry for asking that late, but can you reproduce what you did, please! video is not available sadly

Misaki

warmanw's rig is very cool! That may be the best answer for reproducing a shape with a squashed bottom part with an easy way.

warmanw

The video is available on YouTube