feat: 好几章

2023-04-14 15:41:04 +08:00
parent dbd4e84eae
commit 15c19b9b1e
135 changed files with 8128 additions and 11 deletions
--- a/3.编程思维体系构建/3.4.6.6.绘制地图.md
+++ b/3.编程思维体系构建/3.4.6.6.绘制地图.md
@@ -0,0 +1,336 @@
+# 6.绘制地图
+
+作为一个 RPG 游戏怎么能没有地图呢，<em>是时候绘制地图了！</em>
+
+绘制地图的最佳工具始终是：一支铅笔和一张纸。基本地图由<strong>位置</strong>（矩形）组成，由道路（箭头）连接。我们已经在第 3 章中创建了位置，现在我们将开始添加道路。
+
+在虚拟世界中，“道路”可能是连接两个位置的任何东西：一条路，一扇门，沙漠中。基本上，一段经文具有以下属性：
+
+- 起点（位置）。
+- 目标（位置）。
+- 叙述性描述，例如“森林小径”。
+- 在 <em>go</em> 命令中往哪里走的描述性标记
+
+考虑到这些属性，第 4 章中定义的结构对象就非常适合存储道路了。事实上，一个道路与一个项目或 NPC 并没有太大的不同，它作为“可见出口”存在于某个位置（该位置是起点）。它只是与某些命令的行为不同，特别是命令“go”：应用于道路，<em>go</em>将改变玩家的位置。
+
+```c
+struct object {
+   const char    *description;
+   const char    *tag;
+   struct object *location;
+   struct object *destination;
+};
+```
+
+注意：
+
+- 显然，<em>目的地</em>在大多数其他对象（物品，NPC）中都没有使用
+- 通道总是朝一个方向运行;要双向连接两个位置，我们总是必须创建两个单独的通道。乍一看，这似乎很笨拙，但它确实给了我们很大的灵活性来完善命令“go”的行为
+- 在大地图上，你可能会发现手动创建所有通道很乏味。所以，我强烈建议你使用自定义工具<em>生成</em>地图中重复性更强的部分。这里不会介绍这一点，但您可能会在第 9 章中找到一些灵感，我们将在其中讨论自动胜场。
+
+思考题：为什么创建两个通道可以使我们的程序更加灵活？
+
+接下来我们将展开对象数组
+
+# object.h
+
+```c
+typedef struct object {
+   const char    *description;
+   const char    *tag;
+   struct object *location;
+   struct object *destination;
+} OBJECT;
+
+extern OBJECT objs[];
+
+#define field      (objs + 0)   //是不是觉得这个很熟悉
+#define cave       (objs + 1)
+#define silver     (objs + 2)
+#define gold       (objs + 3)
+#define guard      (objs + 4)
+#define player     (objs + 5)
+#define intoCave   (objs + 6)
+#define exitCave   (objs + 7)
+
+#define endOfObjs  (objs + 8)
+```
+
+# object.c
+
+```c
+#include <stdio.h>
+#include "object.h"
+
+OBJECT objs[] = {
+   {"an open field"  , "field"   , NULL , NULL  },
+   {"a little cave"  , "cave"    , NULL , NULL  },
+   {"a silver coin"  , "silver"  , field, NULL  },
+   {"a gold coin"    , "gold"    , cave , NULL  },
+   {"a burly guard"  , "guard"   , field, NULL  },
+   {"yourself"       , "yourself", field, NULL  },
+   {"a cave entrance", "entrance", field, cave  },
+   {"an exit"        , "exit"    , cave , field }
+};
+```
+
+我们将在 <em>misc.c</em> 中添加一个小的帮助函数，以确定两个给定位置之间是否存在通道。
+
+# misc.h
+
+```c
+extern OBJECT *getPassage(OBJECT *from, OBJECT *to);
+extern OBJECT *actorHere(void);
+extern int listObjectsAtLocation(OBJECT *location);
+```
+
+# misc.c
+
+```c
+#include <stdio.h>
+#include "object.h"
+
+OBJECT *getPassage(OBJECT *from, OBJECT *to)
+{
+   if (from != NULL && to != NULL)
+   {
+      OBJECT *obj;
+      for (obj = objs; obj < endOfObjs; obj++)   //寻找物品之间是否具有通道
+      {
+         if (obj->location == from && obj->destination == to)
+         {
+            return obj;  //找到了
+         }
+      }
+   }
+   return NULL;//找不到
+}
+
+OBJECT *actorHere(void)
+{
+   OBJECT *obj;
+   for (obj = objs; obj < endOfObjs; obj++)
+   {
+      if (obj->location == player->location && obj == guard)
+      {
+         return obj;
+      }
+   }
+   return NULL;
+}
+
+int listObjectsAtLocation(OBJECT *location)
+{
+   int count = 0;
+   OBJECT *obj;
+   for (obj = objs; obj < endOfObjs; obj++)
+   {
+      if (obj != player && obj->location == location)
+      {
+         if (count++ == 0)
+         {
+            printf("You see:\n");
+         }
+         printf("%s\n", obj->description);
+      }
+   }
+   return count;
+}
+```
+
+我们将在命令“go”的实现中使用新功能<em>getPassage</em>来确定是否存在可以将玩家带到所需位置的通道。
+
+# location.h
+
+```c
+extern void executeLook(const char *noun);
+extern void executeGo(const char *noun);
+```
+
+# location.c
+
+```c
+#include <stdio.h>
+#include <string.h>
+#include "object.h"
+#include "misc.h"
+#include "noun.h"
+
+void executeLook(const char *noun)
+{
+   if (noun != NULL && strcmp(noun, "around") == 0)
+   {
+      printf("You are in %s.\n", player->location->description);
+      listObjectsAtLocation(player->location);
+   }
+   else
+   {
+      printf("I don't understand what you want to see.\n");
+   }
+}
+
+void executeGo(const char *noun)
+{
+   OBJECT *obj = getVisible("where you want to go", noun);
+   if (obj == NULL)
+   {
+      // already handled by getVisible
+   }
+   else if (getPassage(player->location, obj) != NULL)
+   //go只会在有地方的时候才会运行起来
+   {
+      printf("OK.\n");
+      player->location = obj;
+      executeLook("around");
+   }
+   else if (obj->location != player->location)
+   {
+      printf("You don't see any %s here.\n", noun);
+   }
+   else if (obj->destination != NULL)
+   {
+      printf("OK.\n");
+      player->location = obj->destination;
+      executeLook("around");
+   }
+   else
+   {
+      printf("You can't get much closer than this.\n");
+   }
+}
+```
+
+我们还将使用新功能<em>getPassage</em>来确定从玩家站立的位置是否可以看到某个位置。未通过通道连接到当前位置的位置不被视为可见。
+
+# noun.h
+
+```c
+extern OBJECT *getVisible(const char *intention, const char *noun);
+extern OBJECT *getPossession(OBJECT *from, const char *verb, const char *noun);
+```
+
+# noun.c
+
+```c
+#include <stdbool.h>
+#include <stdio.h>
+#include <string.h>
+#include "object.h"
+#include "misc.h"
+
+static bool objectHasTag(OBJECT *obj, const char *noun)
+{
+   return noun != NULL && *noun != '\0' && strcmp(noun, obj->tag) == 0;
+}
+
+static OBJECT *getObject(const char *noun)
+{
+   OBJECT *obj, *res = NULL;
+   for (obj = objs; obj < endOfObjs; obj++)
+   {
+      if (objectHasTag(obj, noun))
+      {
+         res = obj;
+      }
+   }
+   return res;
+}
+
+OBJECT *getVisible(const char *intention, const char *noun)
+{
+   OBJECT *obj = getObject(noun);
+   
+   if (obj == NULL)
+   {
+      printf("I don't understand %s.\n", intention);
+   }
+   else if (!(obj == player ||
+              obj == player->location ||
+              obj->location == player ||
+              obj->location == player->location ||
+              getPassage(player->location, obj) != NULL ||   //检查两个位置是否相邻
+              (obj->location != NULL &&
+               (obj->location->location == player ||
+                obj->location->location == player->location))))
+   {
+      printf("You don't see any %s here.\n", noun);
+      obj = NULL;
+   }
+   return obj;
+}
+
+OBJECT *getPossession(OBJECT *from, const char *verb, const char *noun)
+{
+   OBJECT *obj = NULL;
+   if (from == NULL)
+   {
+      printf("I don't understand who you want to %s.\n", verb);
+   }
+   else if ((obj = getObject(noun)) == NULL)
+   {
+      printf("I don't understand what you want to %s.\n", verb);
+   }
+   else if (obj == from)
+   {
+      printf("You should not be doing that to %s.\n", obj->description);
+      obj = NULL;
+   }
+   else if (obj->location != from)
+   {
+      if (from == player)
+      {
+         printf("You are not holding any %s.\n", noun);
+      }
+      else
+      {
+         printf("There appears to be no %s you can get from %s.\n",
+                noun, from->description);
+      }
+      obj = NULL;
+   }
+   return obj;
+}
+```
+
+显然，此示例中的地图是微不足道的：只有两个位置，并且它们在两个方向上都连接在一起。第 12 章将增加第三个地点。
+
+思考题：你能否绘制一张更精细的地图，并将其变成对象列表（位置和通道）
+
+```
+         注：不用当成任务，自行实验即可
+```
+
+输出样例
+
+Welcome to Little Cave Adventure.
+You are in an open field.
+You see:
+a silver coin
+a burly guard
+a cave entrance
+
+--> go entrance
+OK.
+You are in a little cave.
+You see:
+a gold coin
+an exit
+
+--> go exit
+OK.
+You are in an open field.
+You see:
+a silver coin
+a burly guard
+a cave entrance
+
+--> go cave
+OK.
+You are in a little cave.
+You see:
+a gold coin
+an exit
+
+--> quit
+
+Bye!