[Lordzy]

Use the callbacks such as "OnPlayerGiveDamage" and "OnPlayerTakeDamage" to do that. And if you want to lower the damage being done than default damage, I suggest you to set player's team and then manage the damage. While using these callbacks, use GetPlayerDistanceFromPoint function to determine how meters you're away from the player.


For 3z:
Use OnPlayerWeaponShot. And here's an example:

pawn Код:

public OnPlayerWeaponShot(playerid, weaponid, hittype, hitid, Float:fX, Float:fY, Float:fZ)
{
    if(hittype == HIT_TYPE_PLAYER)
    {
        new
            Float:X, Float:Y, Float:Z;
        GetPlayerPos(hitid, X, Y, Z);
        if(GetPlayerDistanceFromPoint(playerid, X, Y, Z) < 4.0)
        {
            //More damage?
        }
        else
        {
            //If more than 3m.
        }
    }
    return 1;
}

The same can be done on with "OnPlayerGiveDamage" or "OnPlayerTakeDamage" in case if it's not for 3x or for 3z versions with lagcompmode Off.