+ SGPlane(const SGVec3<T>& v0, const SGVec3<T>& v1, const SGVec3<T>& v2) :
+ _normal(normalize(cross(v1 - v0, v2 - v0))),
+ _dist(-dot(_normal, v0))
+ { }
+ template<typename S>
+ explicit SGPlane(const SGPlane<S>& plane) :
+ _normal(plane.getNormal()), _dist(plane.getDist())
+ { }