Method getProjection

code/geometry/primitives3d.cpp:38–40

    // length() must not return 0
    return (*this) * (k / length()); }
  point3d getProjection(P(A), P(B)) const {
    point3d v = B - A;
    return A + v.normalize((v % (*this - A)) / v.length()); }
  point3d rotate(P(normal)) const {
    //normal must have length 1 and be orthogonal to the vector
    return (*this) * normal; }