Positionwise everything is gravy, but there is an issue with rotation. If you notice when you rotate the bipeds hand, or the target, the Right Ball remains at its current orientation. You can rotate it manually, but matching is orientation to the hands would be problematic, inaccurate, and generally a pain in the ass.

One solution is to constrain the Right Ball point helpers Rotational Orientation. To keep things simple, we will use a similar setup to the position constraints. Add another Custom Attribute to the Bipeds Right Hand at the same modifier level as the Right Hold Ball Attribute. Name this Ball Right Rotate. Use the same options as the other attribute.

 

 

Animation/Constraints/Orientation Constraint governs the rotational relationships. Select the Right Ball, and constrain the Orientation to the Hand R Target, and the Hand R Ground Target.

 

 

Select the bipeds hand and wire (right click/wire parameters) the Ball Right Rotate slider to the Right ball point helper.

 

 

We wire them the same way as we did the position constraints, one way control direction, with an inverse value setup.

 

Seems like everything is fine. But, when we move the slider, sometimes (depending on your setup) you will get unpredictable rotational results. This is because we have to Align the Hand R Ground Targets rotation to the Right Ball before we animate, to set a 'starting point' so to speak. In order to fix this, we will simply Align* the Hand R Ground Targets and the Right Balls orientation. Now when you change the Right Ball Rotation value, nothing happens. Perfect (since they are both aligned already). Try to rotate the Hand R Ground Target an arbitrary amount. Now edit the slider value (Ball Right Rotate), and the Right Ball will rotate smoothly to the orientation of the Hand R Ground Target.

Align Tool

 

Final Notes: Remember, this technique can be used either with Character Studio Bipeds, or with custom bone setups. Similiar setups can help with mechanical simulations as well.

Questions? Comments? Suggestions for the next tutorial? Feel free to contact me, the webmeister@everflow.com.

 

Next Update : Sample animations and files showing alternate uses for this technique.