What exactly is d representing here? By offset do you mean the distance from the plane to the origin? Or is it like the distance from the point to the line along the vector (a,b,c).
@Tdog The value for d effectively represents the distance of the plane from the origin. That is, for any point (x,y,z), the plane is characterized by the equation a*x + b*y + c*z + d = 0. (a,b,c) represents the normal of the plane and d represents the offset from the origin in this normal direction.
a*x + b*y + c*z + d = 0