编辑“︁HowToWriteAdventureGamesUsingArianne”︁（章节）

===用例===
这些用户案例描述了实体的行为。这有助于我们在编码阶段明确目标的实现。

====玩家的用户案例====
玩家是一个玩游戏的实体，它可以移动，聊天，攻击，治疗。
<pre>
  Player enter village in entry point
  Player moves to Farm zone

  Player talks with Sheep seller
    Player: Hi
    Seller: Greetings! How may I help you?
    Player: buy Sheep
    Seller: Do you want to buy a Sheep for 50 coins?
    Player: yes
    Seller: Thank you! Bye

  Player moves. Sheep follows Player.
  Player moves to plains
  Player moves around looking for food
  Player protect Sheep of wolves attacks

  When Sheep is big enough Player moves to Village
  Player talks with Sheep buyer
    Player: Hi
    Buyer: Greetings! How may I help you?
    Player: sell Sheep
    Buyer: Do you want to sell this Sheep for 73 coins?
    Player: yes
    Buyer: Thank you! Bye

  Player spend money in new Sheep and equipment
  * Armor
  * Weapon
  * Healing potions
</pre>

====绵羊卖家的用例====
这个卖家是一个NPC实体，会卖给我们一只羊，让它长大赚钱。
<pre>
FOREVER do:
  Listen to Player

  If listen "Hi":
    Seller says "Greetings <Player>!"

  If listen "Buy Sheep" from Player:
    Seller says "Do you want to buy a Sheep for 50 coins?"

  If listen "yes" from Player:
    If Player money - 50 > 0:
      set Player money=Player money - 50
      Duplicate Sheep
      Make Sheep follows Player
  Say bye to Player
DONE
</pre>

====绵羊买家的用例====
这个买家是一个NPC实体，它会给我们买羊。
<pre>
FOREVER do:
  Listen to Player

  If listen "Hi":
    Seller says "Greetings <Player>!"

  If listen "Sell Sheep" from Player:
    Estimate Sheep value related to Sheep weight
    Seller says "Do you want to sell your Sheep for <estimated price> coins?"
  
  If listen "yes" from Player:
    set Player money=Player money + <estimated price>
    set Player XP=Player XP + 100 * Sheep Weight / 100
    Destroy Sheep
  
  Say bye to Player
DONE
</pre>

====绵羊的用户案例====
绵羊是我们的关键游戏概念。玩家必须牧羊他们的羔羊，保护他们的狼等，直到他们值得出售。
<pre>
  Sheep is in Farm
  Player buys Sheep
  Sheep seller duplicates Sheep
  Sheep follows Player

  If Sheep finds food:
    Sheep moves to food
    Sheep eats food
    Sheep gains weight

  Player sells Sheep
  Sheep dissappear
</pre>

====狼的用例====
狼是Stendhal的竞争实体。他们一起攻击绵羊，也经常是玩家。他们能很快杀死一只羊。
<pre>
  Wolf moves
  If Wolf sees Sheep:
    Wolf attacks Sheep
  
  If Wolf is attacked:
    Wolf attacks Attacker
</pre>

====老鼠的用例====
老鼠和山洞里的老鼠会攻击玩家，使羊更难长大。
<pre>
  Rat moves
  If Rat sees Player:
    Rat attacks Player
  
  If Rat is attacked:
    Rat attacks Attacker
</pre>

让我们描述每个实体及其属性和操作。