The faces, which far from the camera, disappear when added a sky box to the scene. see the attachments.

    And how to control the distance objects display.

    Thanks in advanced.

Change the far setting on your camera’s lens to a larger number. Note that bigger frustums can have negative effects though, so don’t make it too big. You might want to use fogging to gradually fade your objects out instead.

The far setting can be reached through myView.camera.lens.far.

It works, thanks Richard.
BTW, do you implement the fog effect by particle?
In the 3D effect area, i am a green. can you give me some advice about learning that?

No, the fog effect has nothing to do with particles. The fog effect is made by first calculating the distance from the camera of every vertex in the fogged meshes in the vertex shader. The fragment shader then interpolates this value for each on-screen pixel of the object, and colors the pixel depending on the distance from the camera. All of this happens on the GPU.

i got it. thank you very much.