How do I say JME that objects which are behind other objects shouldn't be drawn?

Troubleshooting graphics
1

How do I say JME that objects which are behind other objects shouldn't be drawn?

If I change the vertexes of one object, JME doesnt clip correct anymore.



Or am I using Frustrum not correct?



cam.setFrustumPerspective(45.f, (float) display.getWidth() / (float) display.getHeight(), 0.1f, 40000);



Thank you,

Ohmari