Attribute channel node

Adds, removes or updates attributes of the input chop.

This 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 and Composite CHOP. Other chops may quietly use the Quaternion attribute, such as the Object, Stretch and Resample chops.

The Scope is needed to specify the channels that will be grouped.

Standard Options and Local Variables

Scope

Selects which channels are X,Y and Z rotations. The channels can be typed in explicitly, or using wildcards. If the number of X,Y and Z rotations selected do not match, an error will occur. Example:

*r[xyz]

Parameters

Quaternion

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.

Scope

Selects which channels are X,Y and Z rotations. The channels can be typed in explicitly, or using wildcards. If the number of X,Y and Z rotations selected do not match, an error will occur. Example: *r[xyz]