@Override
  public void simpleInitApp() {
    initCrossHairs(); // a "+" in the middle of the screen to help aiming
    initKeys();       // load custom key mappings
    initMark();       // a red sphere to mark the hit

    /* Create four colored boxes and a floor to shoot at: */
    shootables = new Node("Shootables");
    rootNode.attachChild(shootables);
    shootables.attachChild(makeCube("a Dragon", -2f, 0f, 1f));
    shootables.attachChild(makeCube("a tin can", 1f, -2f, 0f));
    shootables.attachChild(makeCube("the Sheriff", 0f, 1f, -2f));
    shootables.attachChild(makeCube("the Deputy", 1f, 0f, -4f));
    shootables.attachChild(makeFloor());
    shootables.attachChild(makeCharacter());
  }
Sample 8 - how to let the user pick (select) objects in the scene 
using the mouse or key presses. Can be used for shooting, opening doors, etc.
jme3-examples/src/main/java/jme3test/helloworld/HelloPicking.java