Used to establish a reference frame for StrandOrientation if StrandDeform is true. The vector is expressed relative to the point cloud's local space.

The strand tangent defines the Y axis and this attribute represents the X axis in the point cloud's local coordinates.

If this attribute is not defined, the up-vector is calculated from the camera, which will make the deformations rotate if the camera moves.

If the size of this array does not match StrandPosition, it is ignored.