Hi everyone. Does anyone know the logic behind the node "attributeReorient" ?

I'm trying to write same thing in HDK but I get different result.
What I'm doing is getting rotation matrix from Rest position. For that I'm using for:
x_axis - position of point 0 of the primitive - position of point 1 of the primitive.
y_axis - computeNormal(primitive)
z_axis - cross(x_axis ,y_axis );
building rest matrix from those vectors.
Same thing for the animated position.
Transforming point position by those matrices.
Then promoting values to points.
When geometry is moving but not deforming at all looks the same if I would use "attributeReorient"
But once geometry is deforming then values go off.
I assume it has something to do with interpolation.

I would appreciate if someone could give any advice on that.