private Geometry makeFloor() {
        Box box = new Box(15, .2f, 15);
        Geometry floor = new Geometry("the Floor", box);
        floor.setLocalTranslation(0, -4, -5);
        Material mat1 = new Material(assetManager, "Common/MatDefs/Misc/Unshaded.j3md");
        mat1.setColor("Color", ColorRGBA.Gray);
        floor.setMaterial(mat1);
        return floor;
    }
A floor to show that the "shot" can go through several objects.
jme3-examples/src/main/java/jme3test/collision/TestMousePick.java