bit manipulation - C++ Points of Vertices in Cuboid (Bitwise AND) -

i'm trying calculate points in cuboid given centre (which vector3) , lengths of sides along x, y , z axis. found following on math.stackexchange.com: https://math.stackexchange.com/questions/107778/simplest-equation-for-drawing-a-cube-based-on-its-center-and-or-other-vertices says can use following formulae:

constructor world class is:

world::world(vector3 o, float d1, float d2, float d3) : origin(o) {   // if consider edge length d, need find r such   // 2r = d in order calculate positions of each vertex in world.   float r1 = d1 / 2,       r2 = d2 / 2,       r3 = d3 / 2;    (int = 0; < 8; i++)   {     /* sets vertices of cube.      *      * @see http://bit.ly/1cc2rpg      */     float x = o.getx() + (std::pow(-1, i&1) * r1),           y = o.gety() + (std::pow(-1, i&2) * r2),           z = o.getz() + (std::pow(-1, i&4) * r3);      points[i] = vector3(x, y, z);     std::cout << points[i] << "\n";   } } 

and passing following parameters constructor:

vector3 o(0, 0, 0); world w(o, 100.f, 100.f, 100.f); 

the coordinates being output 8 vertices are:

(50, 50, 50) (-50, 50, 50) (50, 50, 50) (-50, 50, 50) (50, 50, 50) (-50, 50, 50) (50, 50, 50) (-50, 50, 50) 

which cannot correct. guidance appreciated!

the problem lies in bitwise & inside pow calls: in y , z components, return 0 , 2 or 4, respectively. -1^2 = -1^4 = 1, why sign of these components positive. try (i&2)!=0 or (i&2) >> 1 y component instead. same goes z component.