server/random_maps/maze_gen.C


/* peterm@langmuir.eecs.berkeley.edu:  this function generates a random
blocked maze with the property that there is only one path from one spot
to any other, and there is always a path from one spot to any other.

input:  xsize, ysize;
output:  a char** array with # and . for closed and open respectively.

a char value of 0 represents a blank space:  a '#' is
a wall.

*/

/* we need to maintain a list of wall points to generate
   reasonable mazes:  a straightforward recursive random walk maze
   generator would generate a map with a trivial circle-the-outer-wall solution */

#include <stdio.h>
#include <global.h>

/*#include <random_map.h>*/
#include <maze_gen.h>
#include <time.h>


/* this include solely, and only, is needed for the definition of RANDOM */


/* global variables that everyone needs:  don't want to pass them in
   as parameters every time. */
int *wall_x_list = 0;
int *wall_y_list = 0;
int wall_free_size = 0;

/*  heuristically, we need to change wall_chance based on the size of
    the maze. */

int wall_chance;

/* the outsize interface routine:  accepts sizes, returns a char
** maze.  option is a flag for either a sparse or a full maze. Sparse
mazes have sizable rooms. option = 1, full, 0, sparse.*/

char **
maze_gen (int xsize, int ysize, int option)
{
  int i, j;

  /* allocate that array, set it up */
  char **maze = (char **) calloc (sizeof (char *), xsize);

  for (i = 0; i < xsize; i++)
    {
      maze[i] = (char *) calloc (sizeof (char), ysize);
    }

  /* write the outer walls */
  for (i = 0; i < xsize; i++)
    maze[i][0] = maze[i][ysize - 1] = '#';
  for (j = 0; j < ysize; j++)
    maze[0][j] = maze[xsize - 1][j] = '#';


  /* find how many free wall spots there are */
  wall_free_size = 2 * (xsize - 4) + 2 * (ysize - 4);

  make_wall_free_list (xsize, ysize);

  /* return the empty maze */
  if (wall_free_size <= 0)
    return maze;

  /* recursively generate the walls of the maze */
  /* first pop a random starting point */
  while (wall_free_size > 0)
    {
      pop_wall_point (&i, &j);
      if (option)
        fill_maze_full (maze, i, j, xsize, ysize);
      else
        fill_maze_sparse (maze, i, j, xsize, ysize);
    }

  /* clean up our intermediate data structures. */

  free (wall_x_list);
  free (wall_y_list);

  return maze;
}


/*  the free wall points are those outer points which aren't corners or
    near corners, and don't have a maze wall growing out of them already. */

void
make_wall_free_list (int xsize, int ysize)
{
  int i, j, count;

  count = 0;                    /* entries already placed in the free list */
  /*allocate it */
  if (wall_free_size < 0)
    return;
  wall_x_list = (int *) calloc (sizeof (int), wall_free_size);
  wall_y_list = (int *) calloc (sizeof (int), wall_free_size);


  /* top and bottom wall */
  for (i = 2; i < xsize - 2; i++)
    {
      wall_x_list[count] = i;
      wall_y_list[count] = 0;
      count++;
      wall_x_list[count] = i;
      wall_y_list[count] = ysize - 1;
      count++;
    }

  /* left and right wall */
  for (j = 2; j < ysize - 2; j++)
    {
      wall_x_list[count] = 0;
      wall_y_list[count] = j;
      count++;
      wall_x_list[count] = xsize - 1;
      wall_y_list[count] = j;
      count++;
    }
}


/* randomly returns one of the elements from the wall point list */

void
pop_wall_point (int *x, int *y)
{
  int index = RANDOM () % wall_free_size;

  *x = wall_x_list[index];
  *y = wall_y_list[index];
  /* write the last array point here */
  wall_x_list[index] = wall_x_list[wall_free_size - 1];
  wall_y_list[index] = wall_y_list[wall_free_size - 1];
  wall_free_size--;
}


/* find free point:  randomly look for a square adjacent to this one where
we can place a new block without closing a path.  We may only look
up, down, right, or left. */

int
find_free_point (char **maze, int *x, int *y, int xc, int yc, int xsize, int ysize)
{

/* we will randomly pick from this list, 1=up,2=down,3=right,4=left */
  int dirlist[4];
  int count = 0;                /* # elements in dirlist */

  /* look up */
  if (yc < ysize - 2 && xc > 2 && xc < xsize - 2)       /* it is valid to look up */
    {
      int cleartest = (int) maze[xc][yc + 1] + (int) maze[xc - 1][yc + 1] + (int) maze[xc + 1][yc + 1];

      cleartest += (int) maze[xc][yc + 2] + (int) maze[xc - 1][yc + 2] + (int) maze[xc + 1][yc + 2];

      if (cleartest == 0)
        {
          dirlist[count] = 1;
          count++;
        }
    }


  /* look down */
  if (yc > 2 && xc > 2 && xc < xsize - 2)       /* it is valid to look down */
    {
      int cleartest = (int) maze[xc][yc - 1] + (int) maze[xc - 1][yc - 1] + (int) maze[xc + 1][yc - 1];

      cleartest += (int) maze[xc][yc - 2] + (int) maze[xc - 1][yc - 2] + (int) maze[xc + 1][yc - 2];

      if (cleartest == 0)
        {
          dirlist[count] = 2;
          count++;
        }
    }


  /* look right */
  if (xc < xsize - 2 && yc > 2 && yc < ysize - 2)       /* it is valid to look left */
    {
      int cleartest = (int) maze[xc + 1][yc] + (int) maze[xc + 1][yc - 1] + (int) maze[xc + 1][yc + 1];

      cleartest += (int) maze[xc + 2][yc] + (int) maze[xc + 2][yc - 1] + (int) maze[xc + 2][yc + 1];

      if (cleartest == 0)
        {
          dirlist[count] = 3;
          count++;
        }
    }


  /* look left */
  if (xc > 2 && yc > 2 && yc < ysize - 2)       /* it is valid to look down */
    {
      int cleartest = (int) maze[xc - 1][yc] + (int) maze[xc - 1][yc - 1] + (int) maze[xc - 1][yc + 1];

      cleartest += (int) maze[xc - 2][yc] + (int) maze[xc - 2][yc - 1] + (int) maze[xc - 2][yc + 1];

      if (cleartest == 0)
        {
          dirlist[count] = 4;
          count++;
        }
    }

  if (count == 0)
    return -1;                  /* failed to find any clear points */

  /* choose a random direction */
  if (count > 1)
    count = RANDOM () % count;
  else
    count = 0;
  switch (dirlist[count])
    {
      case 1:                  /* up */
        {
          *y = yc + 1;
          *x = xc;
          break;
        };
      case 2:                  /* down */
        {
          *y = yc - 1;
          *x = xc;
          break;
        };
      case 3:                  /* right */
        {
          *y = yc;
          *x = xc + 1;
          break;
        }
      case 4:                  /* left */
        {
          *x = xc - 1;
          *y = yc;
          break;
        }
      default:                 /* ??? */
        {
          return -1;
        }
    }
  return 1;
}

/* recursive routine which will fill every available space in the maze
        with walls*/

void
fill_maze_full (char **maze, int x, int y, int xsize, int ysize)
{
  int xc, yc;

  /* write a wall here */
  maze[x][y] = '#';

  /* decide if we're going to pick from the wall_free_list */
  if (RANDOM () % 4 && wall_free_size > 0)
    {
      pop_wall_point (&xc, &yc);
      fill_maze_full (maze, xc, yc, xsize, ysize);
    }

  /* change the if to a while for a complete maze.  */
  while (find_free_point (maze, &xc, &yc, x, y, xsize, ysize) != -1)
    {
      fill_maze_full (maze, xc, yc, xsize, ysize);
    }
}


/* recursive routine which will fill much of the maze, but will leave
        some free spots (possibly large) toward the center.*/

void
fill_maze_sparse (char **maze, int x, int y, int xsize, int ysize)
{
  int xc, yc;

  /* write a wall here */
  maze[x][y] = '#';

  /* decide if we're going to pick from the wall_free_list */
  if (RANDOM () % 4 && wall_free_size > 0)
    {
      pop_wall_point (&xc, &yc);
      fill_maze_sparse (maze, xc, yc, xsize, ysize);
    }

  /* change the if to a while for a complete maze.  */
  if (find_free_point (maze, &xc, &yc, x, y, xsize, ysize) != -1)
    {
      fill_maze_sparse (maze, xc, yc, xsize, ysize);
    }
}
Revision:	1.5
Committed:	Sun Dec 31 19:02:24 2006 UTC (17 years, 5 months ago) by root
Content type:	text/plain
Branch:	MAIN
Changes since 1.4:	+29 -28 lines
Log Message:	reindent, minor changes
#	User	Rev	Content
1	root	1.5
2	elmex	1.1	/* peterm@langmuir.eecs.berkeley.edu: this function generates a random
3			blocked maze with the property that there is only one path from one spot
4			to any other, and there is always a path from one spot to any other.
5
6			input: xsize, ysize;
7			output: a char** array with # and . for closed and open respectively.
8
9			a char value of 0 represents a blank space: a '#' is
10			a wall.
11
12			*/
13
14			/* we need to maintain a list of wall points to generate
15			reasonable mazes: a straightforward recursive random walk maze
16			generator would generate a map with a trivial circle-the-outer-wall solution */
17
18			#include <stdio.h>
19			#include <global.h>
20	root	1.3
21	elmex	1.1	/#include <random_map.h>/
22			#include <maze_gen.h>
23			#include <time.h>
24
25
26			/* this include solely, and only, is needed for the definition of RANDOM */
27
28
29
30			/* global variables that everyone needs: don't want to pass them in
31			as parameters every time. */
32	root	1.3	int *wall_x_list = 0;
33			int *wall_y_list = 0;
34			int wall_free_size = 0;
35	elmex	1.1
36			/* heuristically, we need to change wall_chance based on the size of
37			the maze. */
38
39	root	1.3	int wall_chance;
40	elmex	1.1
41			/* the outsize interface routine: accepts sizes, returns a char
42			** maze. option is a flag for either a sparse or a full maze. Sparse
43			mazes have sizable rooms. option = 1, full, 0, sparse.*/
44
45	root	1.3	char **
46			maze_gen (int xsize, int ysize, int option)
47			{
48			int i, j;
49	elmex	1.1
50			/* allocate that array, set it up */
51	root	1.3	char maze = (char ) calloc (sizeof (char *), xsize);
52
53			for (i = 0; i < xsize; i++)
54			{
55			maze[i] = (char *) calloc (sizeof (char), ysize);
56			}
57	elmex	1.1
58			/* write the outer walls */
59	root	1.3	for (i = 0; i < xsize; i++)
60			maze[i][0] = maze[i][ysize - 1] = '#';
61			for (j = 0; j < ysize; j++)
62			maze[0][j] = maze[xsize - 1][j] = '#';
63
64
65	elmex	1.1	/* find how many free wall spots there are */
66	root	1.3	wall_free_size = 2 * (xsize - 4) + 2 * (ysize - 4);
67
68			make_wall_free_list (xsize, ysize);
69	elmex	1.1
70			/* return the empty maze */
71	root	1.3	if (wall_free_size <= 0)
72			return maze;
73	elmex	1.1
74			/* recursively generate the walls of the maze */
75			/* first pop a random starting point */
76	root	1.3	while (wall_free_size > 0)
77			{
78			pop_wall_point (&i, &j);
79			if (option)
80			fill_maze_full (maze, i, j, xsize, ysize);
81			else
82			fill_maze_sparse (maze, i, j, xsize, ysize);
83			}
84	elmex	1.1
85			/* clean up our intermediate data structures. */
86	root	1.3
87			free (wall_x_list);
88			free (wall_y_list);
89	elmex	1.1
90			return maze;
91			}
92
93
94
95			/* the free wall points are those outer points which aren't corners or
96			near corners, and don't have a maze wall growing out of them already. */
97
98	root	1.3	void
99			make_wall_free_list (int xsize, int ysize)
100			{
101			int i, j, count;
102
103			count = 0; /* entries already placed in the free list */
104			/allocate it /
105			if (wall_free_size < 0)
106			return;
107			wall_x_list = (int *) calloc (sizeof (int), wall_free_size);
108			wall_y_list = (int *) calloc (sizeof (int), wall_free_size);
109
110	elmex	1.1
111			/* top and bottom wall */
112	root	1.3	for (i = 2; i < xsize - 2; i++)
113			{
114			wall_x_list[count] = i;
115			wall_y_list[count] = 0;
116			count++;
117			wall_x_list[count] = i;
118			wall_y_list[count] = ysize - 1;
119			count++;
120			}
121	elmex	1.1
122			/* left and right wall */
123	root	1.3	for (j = 2; j < ysize - 2; j++)
124			{
125			wall_x_list[count] = 0;
126			wall_y_list[count] = j;
127			count++;
128			wall_x_list[count] = xsize - 1;
129			wall_y_list[count] = j;
130			count++;
131			}
132	elmex	1.1	}
133
134
135
136			/* randomly returns one of the elements from the wall point list */
137
138	root	1.3	void
139			pop_wall_point (int x, int y)
140			{
141			int index = RANDOM () % wall_free_size;
142
143	elmex	1.1	*x = wall_x_list[index];
144			*y = wall_y_list[index];
145			/* write the last array point here */
146	root	1.3	wall_x_list[index] = wall_x_list[wall_free_size - 1];
147			wall_y_list[index] = wall_y_list[wall_free_size - 1];
148	elmex	1.1	wall_free_size--;
149			}
150
151
152
153			/* find free point: randomly look for a square adjacent to this one where
154			we can place a new block without closing a path. We may only look
155			up, down, right, or left. */
156
157	root	1.3	int
158			find_free_point (char *maze, int x, int *y, int xc, int yc, int xsize, int ysize)
159			{
160	elmex	1.1
161			/* we will randomly pick from this list, 1=up,2=down,3=right,4=left */
162	root	1.3	int dirlist[4];
163			int count = 0; /* # elements in dirlist */
164	elmex	1.1
165			/* look up */
166	root	1.3	if (yc < ysize - 2 && xc > 2 && xc < xsize - 2) /* it is valid to look up */
167	elmex	1.1	{
168	root	1.3	int cleartest = (int) maze[xc][yc + 1] + (int) maze[xc - 1][yc + 1] + (int) maze[xc + 1][yc + 1];
169
170			cleartest += (int) maze[xc][yc + 2] + (int) maze[xc - 1][yc + 2] + (int) maze[xc + 1][yc + 2];
171
172			if (cleartest == 0)
173			{
174			dirlist[count] = 1;
175			count++;
176			}
177	elmex	1.1	}
178
179
180			/* look down */
181	root	1.3	if (yc > 2 && xc > 2 && xc < xsize - 2) /* it is valid to look down */
182	elmex	1.1	{
183	root	1.3	int cleartest = (int) maze[xc][yc - 1] + (int) maze[xc - 1][yc - 1] + (int) maze[xc + 1][yc - 1];
184
185			cleartest += (int) maze[xc][yc - 2] + (int) maze[xc - 1][yc - 2] + (int) maze[xc + 1][yc - 2];
186
187			if (cleartest == 0)
188			{
189			dirlist[count] = 2;
190			count++;
191			}
192	elmex	1.1	}
193
194
195			/* look right */
196	root	1.3	if (xc < xsize - 2 && yc > 2 && yc < ysize - 2) /* it is valid to look left */
197	elmex	1.1	{
198	root	1.3	int cleartest = (int) maze[xc + 1][yc] + (int) maze[xc + 1][yc - 1] + (int) maze[xc + 1][yc + 1];
199
200			cleartest += (int) maze[xc + 2][yc] + (int) maze[xc + 2][yc - 1] + (int) maze[xc + 2][yc + 1];
201
202			if (cleartest == 0)
203			{
204			dirlist[count] = 3;
205			count++;
206			}
207	elmex	1.1	}
208
209
210			/* look left */
211	root	1.3	if (xc > 2 && yc > 2 && yc < ysize - 2) /* it is valid to look down */
212	elmex	1.1	{
213	root	1.3	int cleartest = (int) maze[xc - 1][yc] + (int) maze[xc - 1][yc - 1] + (int) maze[xc - 1][yc + 1];
214
215			cleartest += (int) maze[xc - 2][yc] + (int) maze[xc - 2][yc - 1] + (int) maze[xc - 2][yc + 1];
216	root	1.2
217	root	1.3	if (cleartest == 0)
218			{
219			dirlist[count] = 4;
220			count++;
221			}
222	elmex	1.1	}
223
224	root	1.3	if (count == 0)
225			return -1; /* failed to find any clear points */
226	elmex	1.1
227			/* choose a random direction */
228	root	1.3	if (count > 1)
229			count = RANDOM () % count;
230			else
231			count = 0;
232			switch (dirlist[count])
233	elmex	1.1	{
234	root	1.5	case 1: /* up */
235			{
236			*y = yc + 1;
237			*x = xc;
238			break;
239			};
240			case 2: /* down */
241			{
242			*y = yc - 1;
243			*x = xc;
244			break;
245			};
246			case 3: /* right */
247			{
248			*y = yc;
249			*x = xc + 1;
250			break;
251			}
252			case 4: /* left */
253			{
254			*x = xc - 1;
255			*y = yc;
256			break;
257			}
258			default: /* ??? */
259			{
260			return -1;
261			}
262	elmex	1.1	}
263			return 1;
264			}
265
266			/* recursive routine which will fill every available space in the maze
267	root	1.3	with walls*/
268
269			void
270			fill_maze_full (char **maze, int x, int y, int xsize, int ysize)
271			{
272			int xc, yc;
273	elmex	1.1
274			/* write a wall here */
275			maze[x][y] = '#';
276	root	1.3
277	elmex	1.1	/* decide if we're going to pick from the wall_free_list */
278	root	1.3	if (RANDOM () % 4 && wall_free_size > 0)
279			{
280			pop_wall_point (&xc, &yc);
281			fill_maze_full (maze, xc, yc, xsize, ysize);
282			}
283
284			/* change the if to a while for a complete maze. */
285			while (find_free_point (maze, &xc, &yc, x, y, xsize, ysize) != -1)
286			{
287			fill_maze_full (maze, xc, yc, xsize, ysize);
288			}
289	elmex	1.1	}
290
291
292			/* recursive routine which will fill much of the maze, but will leave
293	root	1.2	some free spots (possibly large) toward the center.*/
294	elmex	1.1
295	root	1.3	void
296			fill_maze_sparse (char **maze, int x, int y, int xsize, int ysize)
297			{
298			int xc, yc;
299
300	elmex	1.1	/* write a wall here */
301			maze[x][y] = '#';
302	root	1.3
303	elmex	1.1	/* decide if we're going to pick from the wall_free_list */
304	root	1.3	if (RANDOM () % 4 && wall_free_size > 0)
305			{
306			pop_wall_point (&xc, &yc);
307			fill_maze_sparse (maze, xc, yc, xsize, ysize);
308			}
309
310			/* change the if to a while for a complete maze. */
311			if (find_free_point (maze, &xc, &yc, x, y, xsize, ysize) != -1)
312			{
313			fill_maze_sparse (maze, xc, yc, xsize, ysize);
314			}
315	elmex	1.1	}