positions

GLfloat positions[] = {
    //   x       y       z       w
        0.5,    0.5,    0.0,    1.0,  // position 1
        0.5,   -0.5,    0.0,    1.0,  // position 2
       -0.5,    0.5,    0.0,    1.0,  // position 3
       -0.5,   -0.5,    0.0,    1.0   // position 4
};