4 #include <stddef.h> /* NULL */
5 #include <stdint.h> /* uint8_t, uint16_t, uint32_t, UINT16_MAX */
6 #include <stdlib.h> /* free() */
7 #include "../common/try_malloc.h" /* try_malloc() */
8 #include "hardcoded_strings.h" /* s */
9 #include "thing_actions.h" /* get_thing_action_id_by_name() */
10 #include "things.h" /* struct Thing */
11 #include "world.h" /* global world */
19 /* Write into "neighbors" scores of the N_DIRS immediate neighbors of the
20 * "score_map" cell at "pos_i" (array index), as found in the directions
21 * north-east, east, south-east etc. (clockwise order). Use "max_score" for
22 * illegal neighborhoods (i.e. if direction would lead beyond the map's border).
24 static void get_neighbor_scores(uint16_t * score_map, uint16_t pos_i,
25 uint16_t max_score, uint16_t * neighbors);
27 /* Iterate over scored cells in "score_map" of world.map's geometry. Compare
28 * each cell's score against the score of its immediate neighbors in N_DIRS
29 * directions. If any neighbor's score is at least two points lower than the
30 * current cell's score, re-set it to 1 point higher than its lowest-scored
31 * neighbor. Repeat this whole process until all cells have settled on their
32 * final score. Ignore cells whose score is greater than "max_score". Expect
33 * "max_score" to be the maximum score for cells, marking them as unreachable.
35 static void dijkstra_map(uint16_t * score_map, uint16_t max_score);
37 /* Return numpad char of direction ("8", "6", "2", "4" etc.) of enemy with the
38 * shortest path visible to "t_origin". If no enemy is around, return 0.
40 static char get_dir_to_nearest_enemy(struct Thing * thing_origin);
44 static void get_neighbor_scores(uint16_t * score_map, uint16_t pos_i,
45 uint16_t max_score, uint16_t * neighbors)
47 uint32_t map_size = world.map.length * world.map.length;
49 for (i_dir = 0; i_dir < N_DIRS; neighbors[i_dir] = max_score, i_dir++);
50 uint8_t open_north = pos_i >= world.map.length;
51 uint8_t open_east = pos_i + 1 % world.map.length;
52 uint8_t open_south = pos_i + world.map.length < map_size;
53 uint8_t open_west = pos_i % world.map.length;
54 uint8_t is_indented = (pos_i / world.map.length) % 2;
55 uint8_t open_diag_west = is_indented || open_west;
56 uint8_t open_diag_east = !is_indented || open_east;
57 if (open_north && open_diag_east)
59 neighbors[0] = score_map[pos_i - world.map.length + is_indented];
63 neighbors[1] = score_map[pos_i + 1];
65 if (open_south && open_diag_east)
67 neighbors[2] = score_map[pos_i + world.map.length + is_indented];
69 if (open_south && open_diag_west)
71 neighbors[3] = score_map[pos_i + world.map.length - !is_indented];
75 neighbors[4] = score_map[pos_i - 1];
77 if (open_north && open_diag_west)
79 neighbors[5] = score_map[pos_i - world.map.length - !is_indented];
85 static void dijkstra_map(uint16_t * score_map, uint16_t max_score)
87 uint32_t map_size = world.map.length * world.map.length;
89 uint16_t i_scans, neighbors[N_DIRS], min_neighbor;
90 uint8_t scores_still_changing = 1;
92 for (i_scans = 0; scores_still_changing; i_scans++)
94 scores_still_changing = 0;
95 for (pos = 0; pos < map_size; pos++)
97 if (score_map[pos] <= max_score)
99 get_neighbor_scores(score_map, pos, max_score, neighbors);
100 min_neighbor = max_score;
101 for (i_dirs = 0; i_dirs < N_DIRS; i_dirs++)
103 if (min_neighbor > neighbors[i_dirs])
105 min_neighbor = neighbors[i_dirs];
108 if (score_map[pos] > min_neighbor + 1)
110 score_map[pos] = min_neighbor + 1;
111 scores_still_changing = 1;
120 static char get_dir_to_nearest_enemy(struct Thing * t_origin)
122 /* Calculate for each cell distance to visibly nearest enemy, with movement
123 * possible in the directions or "dir". (Actor's own cells start with 0
124 * distance towards themselves. Cells of actors of own type are invisible.)
126 uint32_t map_size = world.map.length * world.map.length;
127 uint16_t max_score = UINT16_MAX - 1;
128 uint16_t * score_map = try_malloc(map_size * sizeof(uint16_t), __func__);
130 for (i = 0; i < map_size; i++)
132 score_map[i] = UINT16_MAX;
133 if ('.' == t_origin->mem_map[i])
135 score_map[i] = max_score;
138 struct Thing * t = world.things;
139 for (; t != NULL; t = t->next)
141 if ( !t->lifepoints || t == t_origin
142 || 'H' == t_origin->fov_map[t->pos.y * world.map.length + t->pos.x])
146 if (t->lifepoints && t->type == t_origin->type)
148 score_map[t->pos.y * world.map.length + t->pos.x] = UINT16_MAX;
151 score_map[t->pos.y * world.map.length + t->pos.x] = 0;
153 dijkstra_map(score_map, max_score);
155 /* Return direction of "t_origin"'s lowest-scored neighbor cell. */
156 uint16_t neighbors[N_DIRS];
157 uint16_t pos_i = (t_origin->pos.y * world.map.length) + t_origin->pos.x;
158 get_neighbor_scores(score_map, pos_i, max_score, neighbors);
160 char dir_to_nearest_enemy = 0;
161 uint16_t min_neighbor = max_score;
162 char * dirs = "edcxsw"; /* get_neighbor_scores()'s clockwise dir order.*/
163 for (i = 0; i < N_DIRS; i++)
165 if (min_neighbor > neighbors[i])
167 min_neighbor = neighbors[i];
168 dir_to_nearest_enemy = dirs[i];
171 return dir_to_nearest_enemy;
176 extern void ai(struct Thing * t)
178 t->command = get_thing_action_id_by_name(s[S_CMD_WAIT]);
179 char sel = t->fov_map ? get_dir_to_nearest_enemy(t) : 0;/* t->fov_map may */
180 if (0 != sel) /* be absent due */
181 { /* to god command.*/
182 t->command = get_thing_action_id_by_name(s[S_CMD_MOVE]);