The Attribute CHOP adds, removes or updates attributes of the input CHOP. Currently there is only one attribute type, a "quaternion". This attribute type is used to group rotation channel triplets (rx,ry,rz) together.
Rotations sometimes need to be grouped together since interpolations on independent X, Y and Z rotations do not produce smooth results. Rotations often need Quaternion interpolation to rotate through the most direct path.
Operations such as resampling and blending recognize the rotation triplet with the "quaternion" attribute. They blend or resample the rotation channels using "spherical linear interpolation". Ordinary interpolation can produce poor blending results, whereas quaternion blending produces the shortest rotation path between two sets of rotations.
See some of the CHOPs that use the attribute: the Sequence CHOP, Composite CHOP and Interpolate CHOP. Other CHOPs may quietly use the Quaternion attribute, such as the Object CHOP, Stretch CHOP and the Resample CHOP.
The Scope is needed to specify the channels that will be grouped.
Parameters - Quaternion Page
Function - The function to perform on the attributes:
- Pass Through - Leaves the attributes untouched.
- Replace - Erases previous attributes and replaces them with the new ones.
- Append - Keeps previous attributes and combines them with the new attributes. If an attribute already exists on a channel and append attempts to overwrite it, an error will occur.
- Remove - Removes all scoped channels' attributes.
Rotate Order - Sets the rotation order of the rotation triplet.
Standard Options and Local Variables