Multiple CAMERA in scene ...

[AndyGFX]

... how switch between camera entities in scene. I can't find any command in world class or map class for set mainCamera.

[Josh]

You can use camera:SetHidden(true) to hide / show different cameras. A hidden camera will not be shown.

You can also use camera:SetProjectionMode() with PROJECTION_NONE to disable rendering of that camera. This method is better for fast switching between cameras, but will keep directional light shadow data in memory. Hiding the camera will dump all directional light shadow data, and require it to be recreated when the camera is shown again.