pts.push_back (Offset (shifted_box.x ().at (RIGHT), shifted_box.y ().at (UP)));
pts.push_back (Offset (shifted_box.x ().at (LEFT), shifted_box.y ().at (UP)));
pts.push_back (Offset (shifted_box.x ().at (RIGHT), shifted_box.y ().at (UP)));
pts.push_back (Offset (shifted_box.x ().at (LEFT), shifted_box.y ().at (UP)));