how can you make a setup to rig a mecanical tentacle like this in houdini?


http://vimeo.com/3005600 [vimeo.com]

You can create tentacles with as much roll that you wish.

Use the Path Tool to draw your spine backbone. Don't use the Curve tool. Use the Path tool. It will construct nulls along the curve. These nulls are what you manipulate/animate.

Each null creates it's own frame of reference. Just dive in and you will see a normal and an up vector.

These nulls are then merged in to a new object where they are used to construct your spline with all the orientation attributes blended correctly.

Next use the Bones From Curve Tool. Select your curve then the number of bones and set the Kinematic Solver to “Follow Curve”.

This will distribute the bones along the curve and add the appropriate follow curve kinematics. In the case of a spine like what you show, it would make sense to create a bone per backbone joint.

The Bones From Curve Tool is designed to work with this specific path curve and pick up the attributes in the Kinematic CHOP set to spline mode.

Now selecting any of the Spine nulls and manipulating them either transform or rotate will cause the spline to move and the bones to rotate along with the null.

See the attached scene file for an example.