Function SetPlayerVirtualWorld set the virtual world of a player. They can only see other players or vehicles that are in that same world.
The default virtual world is 0.

(playerid, worldid)
int playerid The ID of the player you want to set the virtual world of.
int worldid The virtual world ID to put the player in.

Return Values:
  • 1: The function was executed successfully.
  • 0: The function failed to execute. This means the player is not connected.

if (strcmp(cmdtext, "/world3", true) == 0)
    SetPlayerVirtualWorld(playerid, 3);
    return 1;

Related Functions
The following functions may be useful, as they are related to this function in one way or another.