All cubes are printed by order.  Is possible the last order cube overlap the previous cube?  For example, both cubs are overlapped in some surfaces. Green cube is printed first and blue cube is printed second.  Can jogl allow to display blue cube color on overlapped surfaces only?

Thanks for all your replied.  Two cubes are possible to move anywhere, so I cannot make different z positions.  Is glPolygonOffset able to fix the problem?  Any good example for using glPolygonOffset?  Thanks.

bigger rectangle is green and smaller is blue.  When zooming or rotating the camera, the blue color will disappear sometimes.  I would like the blue is solid on the surface of green rectangle.

there are two size rectangles.  The small one is red and placed inside the big one (green).  My problem is that two rectangles are overlapped and the colors sometimes show red and green if I rotated the camera.  I would like to know how to do to prevent this problem.  I want to show red color on smaller rectangle only.  Thanks.