/* src/server/ai.c */
#include "ai.h"
-#include <stdint.h> /* uint8_t, uint16_t */
-#include <stdlib.h> /* free() */
+#include <stdint.h> /* uint8_t, uint32_t, UINT8_MAX */
#include <string.h> /* strlen(), memset() */
-#include "../common/try_malloc.h" /* try_malloc() */
#include "../common/yx_uint16.h" /* struct yx_uint16 */
#include "map_object_actions.h" /* get_moa_id_by_name() */
#include "map_objects.h" /* struct MapObj */
#include "world.h" /* global world */
-#include "yx_uint16.h" /* yx_uint16_cmp(), mv_yx_in_dir() */
-/* Change cardinal direction string ("NNE" etc.) of any length >1 pointed to by
- * "path_ptr" one step clockwise ("NNE" -> "NEE", "NEE" -> "EEE" etc.).
+/* Write into "neighbor_scores" scores for immediate neighbors to cell at
+ * "pos_yx" (YX coordinates) and "pos_i" (arry_index) in "score_map". Directions
+ * determining neighborhood are defined by the letters of "dir"; their order
+ * also determines in what order scores are written into "neighbor_score".
+ * "len_dirs" is to store the result of a previous strlen(dir) (so it does not
+ * have to be called repeatedly and costly in dijkstra_map(); same reason for
+ * "pos_i"'s redundancy.). "max_score" is written into "neighbor_scores" for
+ * illegal directions (that from "pos_yx" would lead beyond the map's border).
*/
-static void clockwise_path(char ** path_ptr);
-
-/* Return dir char (north = "N" etc.) to enemy nearest to "origin" (beeline). */
-static char nearest_enemy_dir(struct yx_uint16 origin);
+static void get_neighbor_scores(char * dirs, uint8_t len_dirs,
+ uint8_t * score_map, struct yx_uint16 pos_yx,
+ uint32_t pos_i, uint8_t max_score,
+ uint8_t * neighbor_scores)
+{
+ memset(neighbor_scores, max_score, len_dirs);
+ uint8_t i_dirs;
+ for (i_dirs = 0; i_dirs < len_dirs; i_dirs++)
+ {
+ if ('N' == dirs[i_dirs] && pos_yx.y > 0)
+ {
+ neighbor_scores[i_dirs] = score_map[pos_i - world.map.size.x];
+ }
+ else if ('E' == dirs[i_dirs] && pos_yx.x < world.map.size.x - 1)
+ {
+ neighbor_scores[i_dirs] = score_map[pos_i + 1];
+ }
+ else if ('S' == dirs[i_dirs] && pos_yx.y < world.map.size.y - 1)
+ {
+ neighbor_scores[i_dirs] = score_map[pos_i + world.map.size.x];
+ }
+ else if ('W' == dirs[i_dirs] && pos_yx.x > 0)
+ {
+ neighbor_scores[i_dirs] = score_map[pos_i - 1];
+ }
+ }
+}
-static void clockwise_path(char ** path_ptr)
+/* Iterate over scored cells in "score_map" of world.map's 2D geometry. Compare
+ * each cell's score against the scores of its immediate neighbors in "dirs"
+ * directions; if at least one of these is lower, re-set the current cell's
+ * score to one higher than its lowest neighbor score. Repeat this whole process
+ * until all cells have settled on their final score. Ignore cells whose
+ * position in "score_map" fits a non-island cell in world.map.cells. Expect
+ * "max_score" to be the maximum score for cells, marking them as unreachable.
+ */
+static void dijkstra_map(char * dirs, uint8_t * score_map, uint8_t max_score)
{
- char * path = * path_ptr;
- char old_char = path[0];
- char new_char = 'N';
- if ('N' == old_char)
- {
- new_char = 'E';
- }
- else if ('E' == old_char)
- {
- new_char = 'S';
- }
- else if ('S' == old_char)
+ uint8_t len_dirs = strlen(dirs);
+ uint8_t neighbor_scores[len_dirs];
+ struct yx_uint16 pos_yx;
+ uint32_t pos_i;
+ uint8_t i_scans, i_dirs, local_score, min_neighbor_score;
+ uint8_t scores_still_changing = 1;
+ for (i_scans = 0; scores_still_changing; i_scans++)
{
- new_char = 'W';
- }
- uint8_t len = strlen(path);
- uint8_t i = 0;
- for (; i < len; i++)
- {
- uint8_t next_i = i + 1;
- if (next_i == len || old_char != path[next_i])
+ scores_still_changing = 0;
+ for (pos_yx.y = 0, pos_i = 0; pos_yx.y < world.map.size.y; pos_yx.y++)
{
- break;
+ for (pos_yx.x = 0; pos_yx.x < world.map.size.x; pos_yx.x++, pos_i++)
+ {
+ if ('.' == world.map.cells[pos_i])
+ {
+ local_score = score_map[pos_i];
+ get_neighbor_scores(dirs, len_dirs, score_map, pos_yx,
+ pos_i, max_score, neighbor_scores);
+ min_neighbor_score = max_score;
+ for (i_dirs = 0; i_dirs < len_dirs; i_dirs++)
+ {
+ if (min_neighbor_score > neighbor_scores[i_dirs])
+ {
+ min_neighbor_score = neighbor_scores[i_dirs];
+ }
+ }
+ if (local_score > min_neighbor_score + 1)
+ {
+ score_map[pos_i] = min_neighbor_score + 1;
+ scores_still_changing = 1;
+ }
+ }
+ }
}
}
- path[i] = new_char;
}
-static char nearest_enemy_dir(struct yx_uint16 origin)
+/* Return char of direction ("N", "E", "S" or "W") of enemy with the shortest
+ * path to "mo_target". If no enemy is around, return 0.
+ */
+static char get_dir_to_nearest_enemy(struct MapObj * mo_target)
{
- char * f_name = "nearest_enemy_dir()";
- struct MapObj * mo;
- char sel = 0;
- uint16_t dist_max = world.map.size.y;
- if (world.map.size.x > world.map.size.y)
+ /* Calculate for each cell the distance to the nearest map actor that is
+ * not "mo_target", with movement only possible in the directions of "dir".
+ * (Actor's own cells start with a distance of 0 towards themselves.)
+ */
+ uint8_t max_score = UINT8_MAX; /* Score for cells treated as unreachable. */
+ char * dirs = "NESW";
+ uint8_t score_map[world.map.size.y * world.map.size.x];
+ memset(score_map, max_score, world.map.size.y * world.map.size.x);
+ struct MapObj * mo = world.map_objs;
+ for (; mo != NULL; mo = mo->next)
{
- dist_max = world.map.size.x;
+ if (!mo->lifepoints || mo == mo_target)
+ {
+ continue;
+ }
+ score_map[(mo->pos.y * world.map.size.x) + mo->pos.x] = 0;
}
- uint8_t escape = 0;
- uint8_t dist, j;
- uint16_t i;
- for (dist = 1; !escape && dist <= dist_max; dist++)
+ dijkstra_map(dirs, score_map, max_score);
+
+ /* Return direction of "mo_target"'s lowest-scored neighbor cell. */
+ uint8_t len_dirs = strlen(dirs);
+ uint32_t pos_i = (mo_target->pos.y * world.map.size.x) + mo_target->pos.x;
+ uint8_t neighbor_scores[len_dirs];
+ get_neighbor_scores(dirs, len_dirs, score_map, mo_target->pos, pos_i,
+ max_score, neighbor_scores);
+ char dir_to_nearest_enemy = 0;
+ uint8_t min_neighbor_score = max_score;
+ uint8_t i_dirs;
+ for (i_dirs = 0; i_dirs < len_dirs; i_dirs++)
{
- char * path = try_malloc(dist + 1, f_name);
- memset(path, 'N', dist);
- path[dist] = '\0';
- for (i = 0; !escape && i < (dist * 4); i++)
+ if (min_neighbor_score > neighbor_scores[i_dirs])
{
- clockwise_path(&path);
- struct yx_uint16 testpos = origin;
- for (j = 0; j < dist; j++)
- {
- testpos = mv_yx_in_dir(path[j], testpos);
- }
- if (yx_uint16_cmp(&testpos, &origin) ||
- testpos.y > world.map.size.y || testpos.x > world.map.size.x)
- {
- continue;
- }
- for (mo = world.map_objs; mo != 0; mo = mo->next)
- {
- if (mo->lifepoints && 1 == yx_uint16_cmp(&testpos, &mo->pos))
- {
- sel = path[0];
- escape = 1;
- break;
- }
- }
+ min_neighbor_score = neighbor_scores[i_dirs];
+ dir_to_nearest_enemy = dirs[i_dirs];
}
- free(path);
}
- return sel;
+ return dir_to_nearest_enemy;
}
-extern void pretty_dumb_ai(struct MapObj * mo)
+extern void ai(struct MapObj * mo)
{
mo->command = get_moa_id_by_name("wait");
- char sel = nearest_enemy_dir(mo->pos);
+ char sel = get_dir_to_nearest_enemy(mo);
if (0 != sel)
{
mo->command = get_moa_id_by_name("move");
projects / plomrogue / commitdiff