@Override
  public void simpleInitApp() {
    /* Set up Physics Game */
    bulletAppState = new BulletAppState();
    stateManager.attach(bulletAppState);
    /* Configure cam to look at scene */
    cam.setLocation(new Vector3f(0, 4f, 6f));
    cam.lookAt(new Vector3f(2, 2, 0), Vector3f.UNIT_Y);
    /* Initialize the scene, materials, inputs, and physics space */
    initInputs();
    initMaterials();
    initWall();
    initFloor();
    initCrossHairs();
  }
dimensions used for bricks and wall
jme3-examples/src/main/java/jme3test/helloworld/HelloPhysics.java