Method leftOfPlaneFast

Determines if a point d is left of the plane defined by the points a, b, and c. The latter are assumed to be in CCW order, as viewed from the right side of the plane. Note: this fast method may return an incorrect result. @param xa x coordinate of point a. @param ya y coordinate of poin

(
    double xa, double ya, double za,
    double xb, double yb, double zb,
    double xc, double yc, double zc,
    double xd, double yd, double zd)