[iggy1]

Like MP2 said.

pawn Code:

new some_area = CreateDynamicRectangle(...);

public OnPlayerEnterDynamicArea(playerid, areaid)
{
    if(areaid == some_area)
    {
        SendClientMessage(playerid, -1, "you are in");//this will be sent once and wont spam
    }
    return 1;
}

It would require a lot more code to do it properly inside OnPlayerUpdate which i haven't got the time to write and test.