[efeX]

You can't make them NOT spawn, BUT you can do a check to see if they have logged in before spawning and deny them...
This code isn't tested/nor expected to work, just an example

Код:

new PlayerState[MAX_PLAYERS];

public OnPlayerSpawn(playerid)
{
  if (PlayerState[playerid] == 0) // not logged in?
  {
   SendClientMessage(playerid, 0xFFFFFFFF, "You must login before spawning!");
   Kick(playerid);
  }
}