 This class implements the basis services for the creation, edition, modification and evaluation of planar offset curve. The offset curve is obtained by offsetting by distance along the normal to a basis curve defined in 2D space. The offset curve in this package can be a self intersecting curve even if the basis curve does not selfintersect. The self intersecting portions are not deleted at the construction time. An offset curve is a curve at constant distance (Offset) from a basis curve and the offset curve takes its parametrization from the basis curve. The Offset curve is in the direction of the normal to the basis curve N. The distance offset may be positive or negative to indicate the preferred side of the curve : . distance offset >0 => the curve is in the direction of N . distance offset >0 => the curve is in the direction of  N On the Offset curve : Value(u) = BasisCurve.Value(U) + (Offset * (T ^ Z)) / T ^ Z where T is the tangent vector to the basis curve and Z the direction of the normal vector to the plane of the curve, N = T ^ Z defines the offset direction and should not have null length. More...
