Rigging and Skinning - Animating with Blender: How to Create Short Animations from Start to Finish - page 156

Back in Pose mode, this bone is assigned a StretchTo constraint, with the sternum bone as the target. As
constraints automatically target bone roots, and we want it to point to the tip of the sternum bone, we have
to adjust the Head/Tail parameter in the constraint. Head/Tail is a new rigging feature that lets certain
constraints target any point along a bone instead of just the root (the tail ). For the mother's new stomach
bone, this has been changed to a value of 1.0, which is the tip ( head) of the sternum bone. The new bone
is made an unconnected child of the base of the spine so that it forms a “solid” area between the roots of the
two bones.

Now when the armature is manipulated, the root of the new bone moves in conjunction with the spine,
while the bone itself stretches, squashes, and otherwise contorts itself to follow the sternum bone. We have
created a stretchable structure that approximates the abdominal muscles. Figures 9.50-9.52 show the fi nal
construction along with the StretchTo constraint panel.

9.50 9.51

9.52

Figures 9.50-9.52 The stretching abdominal bone