In the previous releases of MotionBuilder, the user had limited control on the behavior of Roll bones when rotating a limb of a character. This was a usability issue with the HumanIK implementation in both Maya and MotionBuilder. Moreover, the terminology used to refer properties and the manner in which they were exposed caused confusion to the user.
The new HIK 4.5 Character Solver is now implemented in both Maya and MotionBuilder. This Solver contains all the required Roll bone properties to solve this usability issue. Now the properties are easy to use and allow a user to decide which bone will be influenced to what degree, for a given limb. For example, Forearm Roll will be influenced to 40% and Elbow at 0%.
The property names are also changed to be consistent in Maya and MotionBuilder. The old Roll bone property names and their corresponding new names are listed in the following table:
| Old Roll bone property name | New Roll bone property name |
|---|---|
| LeftForeArmRollEx | Left Forearm Roll |
| Left ForeArm Roll | Left Elbow Roll |
| LeftArmRollEx | Left Arm Roll |
| Left Arm Roll | Left Shoulder Roll |
| RightForeArmRollEx | Right Forearm Roll |
| RightForeArm Roll | Right Elbow Roll |
| RightArmRollEx | Right Arm Roll |
| Right Arm Roll | Right Shoulder Roll |
| LeftLegRollEx | Left Leg Roll |
| Left Leg Roll | Left Knee Roll |
| LeftUpLegRollEx | Left UpLeg Roll |
| Left UpLeg Roll | Left Hip Roll |
| RightLegRollEx | Right Leg Roll |
| Right Leg Roll | Right Knee Roll |
| RightUpLegRollEx | Right UpLeg Roll |
| Right UpLeg Roll | Right Hip Roll |
New Roll bone properties and their values
For the property values, the value of a Roll bone (Left Forearm Roll) cannot be higher than the corresponding <parent> Roll value (Left Elbow Roll). You cannot extract more on the Roll bone than on the corresponding Elbow, only less. The same applies to the shoulder and Leg Roll values.
When Roll bones do not exist or not defined, the corresponding Roll bone property will be disabled (non-editable), and the remaining Roll properties will be applied to the corresponding parent (Elbow, Shoulder, UpLeg, and Knee).
The Roll amount is defined by the Roll Extraction Mode. The two extraction modes are:
