Source Thread: http://rmrk.net/index.php/topic,40114.0.html

  전투후 몬스터가 드롭하는 아이템의 가짓수를 확장하는 스크립트입니다.  추가 드롭아이템이 나올 확률, 입수하는 돈의 액수 범위등을 조정할 수 있습니다.

**이 스크립트는 사용하는 전투 시스템과 호환성이 없을 수도 있습니다.  또한 스크립트로 추가된 루트 아이템은 몬스터 정보 스크립트(도감류)에 표시되지 않을 수 있습니다.

#==============================================================================
#    Drop Options
#    Version: 1.1
#    Author: modern algebra (rmrk.net)
#    Date: September 11, 2010
#++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
#  Description:
#
#    This script is very simple. All it does is allow you to make item drops a
#   little less static in some very simple ways: 
#   (a) you can make more than two drops for each enemy, so enemies can drop a 
#      greater variety of loot; 
#   (b) you can place a cap on the amount of these extra drops, so if you want 
#      a boss to have a 100% chance of dropping one of three items, but only 
#      one,then you can do that; and
#   (c) you can randomize the amount of gold dropped by setting a range within
#      which it can fall.
#
#    If you are using any scripts that show loot drops of enemies (such as a 
#   bestiary), the effects of this script will not be reflected in that without
#   direct modifications. If you are using such a script, please feel free to 
#   post a link to it in this script's thread in RMRK and I will write a patch
#   for it.
#
#    This script may not work with some custom battle systems, particularly 
#   ones that do not use troops.
#++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
#  Instructions:
#
#    Place this script above Main and below any other scripts in the Script 
#   Editor (F11).
#
#    All configuration happens in the note boxes of enemies. If you wish to add
#   a new drop, place this code in a note box for the enemy:
#      drop[type id, probability]
#        type        : the type, either Item, Weapon, or Armor. Armour is also
#                     accepted.
#        id          : This is the ID of the item, weapon, or armor.
#        probability : This is the probability the item, weapon, or armor will
#                     drop. If you put a % sign after the number, then it will
#                     drop that percentage of the time. If not, then the number
#                     you put here will be the denominator, same as with 
#                     regular drops. The number has to be an integer.
#    EXAMPLES:
#      drop[Item 1, 65%]
#          This will mean that the item with ID 1 (Potion by default) will drop
#         65% of the time when you kill this enemy.
#      drop[armor 5, 8]
#          This will mean that the armor with ID 5 (Mithril Shield by default)
#         will drop 1/8 times you kill this enemy.
#
#    To set a maximum on the number of extra drops (note that this only applies
#   to extra drops set up in the note field - the two default drops are exempt 
#   from this cap), you can use the code:
#      max_drop[x]
#         x : the maximum amount of extra drops that you want.
#   EXAMPLE:
#    If an enemy is set up like this:
#      drop[weapon 20, 100%]
#      drop[weapon 21, 100%]
#      max_drop[1]
#    Then that means that the enemy will definitely drop either Weapon 20 
#   (Mythril Spear) or Weapon 21 (Mythril Blade), but will not drop both since 
#   the max_drop code prevents it from dropping more than one of the notebox
#   drops.
#
#    To randomize the amount of gold an enemy drops, place the following code 
#   in its note box:
#      gold[variance]
#        variance : this is an integer, and the amount of gold dropped is 
#          calculated by randomly selecting a number between 0 and this value,
#          and then adding it to the regular gold drop you set in the database.
#    EXAMPLE:
#      If an enemy has 5 gold set as its drop in the database, then the 
#     following note:
#        gold[12]
#      will mean that the enemy will drop anywhere between 5 and 17 gold upon
#     its death.
#==============================================================================

#==============================================================================
# ** RPG::Enemy
#++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
#  Summary of Changes:
#    aliased method - gold
#    new method - random_gold, extra_drops
#==============================================================================

class RPG::Enemy
  #~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  # * Gold
  #~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  alias ma_drpopt_gold_2go9 gold unless self.method_defined? (:ma_drpopt_gold_2go9)
  def gold (*args)
    return (rand (random_gold + 1)) + ma_drpopt_gold_2go9 (*args)
  end
  #~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  # * Random Gold
  #~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  def random_gold
    (@rand_gold = self.note[/GOLD[(d+)]/i] != nil ? $1.to_i : 0) if !@rand_gold
    return @rand_gold
  end
  #~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  # * Extra Drops
  #~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  def extra_drops
    if @extra_drops.nil?
      @extra_drops = []
      self.note.gsub (/DROP[(item|weapon|armou?r)s*(d+),?s*(d+)(%?)]/i) {
        drop = RPG::Enemy::DropItem.new
        case $1.downcase
        when "item"
          drop.kind = 1
          drop.item_id = $2.to_i
        when "weapon"
          drop.kind = 2
          drop.weapon_id = $2.to_i
        else
          drop.kind = 3
          drop.armor_id = $2.to_i
        end
        drop.denominator = $4.empty? ? $3.to_i : $3.to_f
        @extra_drops.push (drop)
      }
    end
    return @extra_drops
  end
  #~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  # * Max Drops
  #~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  def max_drops
    if !@max_drops
      @max_drops = self.note[/MAX[ _]DROPS?[(d+)]/i].nil? ? 999 : $1.to_i
    end
    return @max_drops
  end
  # If using Note Editor
  if self.method_defined? (:ma_reset_note_values)
    #~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    # * Reset Note Values
    #~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    alias mala_nedo_restnte_9yn2 ma_reset_note_values
    def ma_reset_note_values (*args)
      mala_nedo_restnte_9yn2 (*args) # Run Original Method
      @rand_gold, @extra_drops, @max_drops = nil, nil, nil
    end
  end
end

#==============================================================================
# ** Game_Troop
#++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
#  Summary of Changes:
#    aliased method - make_drop_items
#==============================================================================

class Game_Troop
  #~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  # * Create Array of Dropped Items
  #~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  alias mlgb_drpop_mkeitm_4rx1 make_drop_items
  def make_drop_items (*args)
    drop_items = mlgb_drpop_mkeitm_4rx1 (*args)
    for enemy in dead_members
      ie_drops = []
      for di in enemy.enemy.extra_drops
        next if di.kind == 0
        if di.denominator.is_a? (Float)
          next if rand (100) > di.denominator
        else
          next if rand(di.denominator) != 0
        end
        case di.kind
        when 1 then ie_drops.push($data_items[di.item_id])
        when 2 then ie_drops.push($data_weapons[di.weapon_id])
        when 3 then ie_drops.push($data_armors[di.armor_id])
        end
      end
      while ie_drops.size > enemy.enemy.max_drops
        ie_drops.delete_at (rand (ie_drops.size))
      end
      drop_items += ie_drops
    end
    return drop_items
  end
end