function drawMagnet (centerx,centery,magnetThick)
  mi_addnode(centerx-magnetThick/2,centery+magnetThick/2);
  mi_addnode(centerx+magnetThick/2,centery+magnetThick/2);
  mi_addnode(centerx-magnetThick/2,centery-magnetThick/2);
  mi_addnode(centerx+magnetThick/2,centery-magnetThick/2);
  mi_drawline(centerx-magnetThick/2,centery+magnetThick/2,centerx+magnetThick/2,centery+magnetThick/2);
  mi_drawline(centerx+magnetThick/2,centery+magnetThick/2,centerx+magnetThick/2,centery-magnetThick/2);
  mi_drawline(centerx+magnetThick/2,centery-magnetThick/2,centerx-magnetThick/2,centery-magnetThick/2);
  mi_drawline(centerx-magnetThick/2,centery-magnetThick/2,centerx-magnetThick/2,centery+magnetThick/2);
end