Rotates each curve towards its facing direction.
Each curve in the Input Curves about the cross axis from its original geometric direction
to its provided direction.
The rotation of each vertex of a primitive about that primitive's root is a ramp from
Rotate Root to Tip.
The ramp can be made non-linear with the Gamma.
An additional Random rotation can be applied to each overall primitive.
The rotation is made towards each primitive's facing direction,
specified by the primitive vector Facing Attribute.
For each primitive, a rotation axis is determined by the cross product of the original root to tip vector
against the vector in the facing attribute.
tested in Houdini
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