Trueif this is planar within the given tolerance, and
The planarity condition is computed by the following algorithm. The normal vector <A, B, C> is determined by the vertices of this multisurface using Newell’s method. For the first point (x’, y’, z’) of this multisurface, we compute D’ = Ax’ + By’ + Cz’. Then, this multisurface is planar if and only if every subsequent point (x, y, z) of this multisurface gives a D = Ax + By + Cz, that is within the tolerance amount of D’. That is, | D - D’ | <= tolerance.
If the specified tolerance is negative, then this method always returns