[Kindred]

pawn Код:

if(IsPlayerInRangeOfPoint(playerid, Float:range, Float:x, Float:y, Float:z))
{
    //Code that happens if they are in range of point
}
else
{
   //Code that happens if they are not in range of point
}

This checks if a player is in range of a point. If you want the server to check if the player is near a point every certain amount of seconds, use a timer, or use OnPlayerUpdate, which is called nearly 20 times a second (if not incorrect).