same scene , different render result?

Hi All:

I am designing a project using VC++&OpenGL, and now I experience a strange problem which is presented below.
A scene is rendered the first time, the appearance is right. but when i rotate the whole scene, the scene looked strange, for example ,a wall painting with texture seems to have been cutted and seperated into several parts, some parts of the picture is not showed correctly. who can tell me the reason?

I am sorry for my poor english. Do I make myself clear? And can anybody help me?
Thanks a lot!

Can’t see anything …
But make sure you clear the depth buffer before rendering each frame.
If you disable depth writes at some point (ie glDepthMask(0); ), reenable them before attempting a clear.
Also note that the scissor rectangle (if any) constrains the clear region.

The problem described could also be Z-Fighting. Try increasing the distance to the near-clip plane in your projection setup.

Good luck,
– Jeff

Thank you very much!!
I have changed the near clip , set it further; so the result is correct now!
The reason is z-fighting.
Thanks again!