1 /* src/server/field_of_view.c */
3 #define _POSIX_C_SOURCE 200809L /* strdup() */
4 #include "field_of_view.h"
5 #include <stdlib.h> /* free() */
6 #include <stdint.h> /* uint8_t, uint16_t, uint32_t */
7 #include <string.h> /* memset(), strchr(), strdup() */
8 #include "../common/rexit.h" /* exit_trouble() */
9 #include "../common/try_malloc.h" /* try_malloc() */
10 #include "map.h" /* yx_to_map_pos() */
11 #include "map_objects.h" /* MapObj */
12 #include "yx_uint8.h" /* yx_uint8 */
13 #include "world.h" /* global world */
17 /* Values for mv_yx_in_dir_wrap()'s wrapping directory memory. */
26 /* Transform "yx" to an index position in the world map. */
27 //static uint16_t yx_to_pos(struct yx_uint8 * yx);
29 /* Move "yx" into hex direction "d". If this moves "yx" beyond the minimal (0)
30 * or maximal (UINT8_MAX) column or row, it wraps to the opposite side. Such
31 * wrapping is returned as a wraps enum value and stored, so that further calls
32 * to move "yx" back into the opposite direction may unwrap it again. Pass an
33 * "unwrap" of UNWRAP to re-set the internal wrap memory to 0.
35 static uint8_t mv_yx_in_dir_wrap(char d, struct yx_uint8 * yx, uint8_t unwrap);
37 /* Wrapper to "mv_yx_in_dir_wrap()", returns 1 if the wrapped function moved
38 * "yx" within the wrap borders and the map size, else 0.
40 extern uint8_t mv_yx_in_dir_legal(char dir, struct yx_uint8 * yx);
42 /* Return one by one hex dir characters of walking through a circle of "radius".
43 * The circle is initialized by passing a "new_circle" of 1 and the "radius"
44 * and only returns non-null hex direction characters if "new_circle" is 0.
46 static char next_circle_dir(uint8_t new_circle, uint8_t radius_new);
48 /* Draw circle of hexes flagged LIMIT "radius" away from "yx" to "fov_map". */
49 extern void draw_border_circle(struct yx_uint8 yx, uint8_t radius,
52 /* eye_to_cell_dir_ratio() helper. */
53 static void geometry_to_char_ratio(uint8_t * n1, uint8_t * n2, uint8_t indent,
54 int16_t diff_y, int16_t diff_x,
55 uint8_t vertical, uint8_t variant);
57 /* From the chars in "available_dirs" and the geometry described by the other
58 * parameters return a string of hex direction characters representing the
59 * approximation of a straight line. "variant" marks the direction as either in
60 * the northern, north-eastern or south-western hex neighborhood if 1, or the
63 static char * eye_to_cell_dir_ratio(char * available_dirs, uint8_t indent,
64 int16_t diff_y, int16_t diff_x,
65 uint8_t vertical, uint8_t variant,
68 /* Return string approximating in one or two hex direction chars the direction
69 * that a "diff_y" and "diff_x" lead to in the internal half-indented 2D
70 * encoding of hexagonal maps, with "indent" the movement's start indentation.
72 static char * dir_from_delta(uint8_t indent, int16_t diff_y, int16_t diff_x);
74 /* Return string of hex movement direction characters describing the best
75 * possible hex approximation to a straight line from "yx_eye" to "yx_cell". If
76 * "right" is set and the string is of length two, return it with the direction
77 * strings scarcer character appearing first.
79 static char * eye_to_cell(struct yx_uint8 * yx_eye, struct yx_uint8 * yx_cell,
82 /* Return string of hex movement direction characters describing the best
83 * possible hex approximation to a straight line from "yx_eye" to "yx_cell". If
84 * "right" is set and the string is of length two, return it with the direction
85 * strings scarcer character appearing first.
87 static char * eye_to_cell(struct yx_uint8 * yx_eye, struct yx_uint8 * yx_cell,
90 /* fill_shadow() helper, determining if map's top left cell starts a shadow. */
91 static uint8_t is_top_left_shaded(uint16_t pos_a, uint16_t pos_b,
94 /* Flag as HIDDEN all cells in "fov_map" that are enclosed by 1) the map's
95 * borders or cells flagged LIMIT and 2) the shadow arms of cells flagged
96 * SHADOW_LEFT and SHADOW_RIGHT extending from "yx_cell", as seen as left and
97 * right as seen from "yx_eye". "pos_a" and "pos_b" store the terminal positions
98 * of these arms in "fov_map" ("pos_a" for the left, "pos_b" for the right one).
100 static void fill_shadow(struct yx_uint8 * yx_eye, struct yx_uint8 * yx_cell,
101 uint8_t * fov_map, uint16_t pos_a, uint16_t pos_b);
103 /* Flag with "flag" cells of a path from "yx_start" to the end of the map or (if
104 * closer) the view border circle of the cells flagged as LIMIT, in a direction
105 * parallel to the one determined by walking a path from "yx_eye" to the cell
106 * reachable by moving one step into "dir" from "yx_start". If "shift_right" is
107 * set, choose among the possible paths the one whose starting cell is set most
108 * to the right, else do the opposite.
110 static uint16_t shadow_arm(struct yx_uint8 * yx_eye, struct yx_uint8 * yx_start,
111 uint8_t * fov_map, char dir, uint8_t flag,
112 uint8_t shift_right);
114 /* From "yx_start", draw shadow of what is invisible as seen from "yx_eye" into
115 * "fov_map" by extending shadow arms from "yx_start" as shadow borders until
116 * the edges of the map or, if smaller, the maximum viewing distance, flag these
117 * shadow arms' cells as HIDE_LATER and the area enclosed by them as HIDDEN.
118 * "dir_left" and "dir_right" are hex directions to move to from "yx_start" for
119 * cells whose shortest straight path to "yx_eye" serve as the lines of sight
120 * enclosing the shadow left and right (left and right as seen from "yx_eye").
122 static void shadow(struct yx_uint8 * yx_eye, struct yx_uint8 * yx_start,
123 uint8_t * fov_map, char dir_left, char dir_right);
125 /* In "fov_map", if cell of position "yx_cell" is not HIDDEN, set it as VISIBLE,
126 * and if an obstacle to view is positioned there in the game map, flag cells
127 *behind it, unseen from "yx_eye", as HIDDEN on the interior and HIDE_LATER on
130 * The shape and width of shadows is determined by 1) calculating an approximate
131 * direction of "yx_cell" as seen from "yx_eye" as one hex movement direction,
132 * or two directly neighboring each other (i.e. "east", "east and north-east"),
133 * 2) deriving the two hex movement directions clockwise immediately preceding
134 * the first (or only) direction and immediately succeeding the second (or only)
135 * one and 3) passing the two directions thus gained as shadow arm direction
136 * calibration values to shadow() (after this function's other arguments).
138 static void set_view_of_cell_and_shadows(struct yx_uint8 * yx_cell,
139 struct yx_uint8 * yx_eye,
144 static uint8_t mv_yx_in_dir_wrap(char d, struct yx_uint8 * yx, uint8_t unwrap)
146 static uint8_t wrap = 0;
152 struct yx_uint8 original;
157 yx->x = yx->x + (yx->y % 2);
166 yx->x = yx->x + (yx->y % 2);
171 yx->x = yx->x - !(yx->y % 2);
180 yx->x = yx->x - !(yx->y % 2);
185 exit_trouble(1, "mv_yx_in_dir_wrap()", "illegal direction");
187 if (strchr("edc", d) && yx->x < original.x)
189 wrap = wrap & WRAP_W ? wrap ^ WRAP_W : wrap | WRAP_E;
191 else if (strchr("xsw", d) && yx->x > original.x)
193 wrap = wrap & WRAP_E ? wrap ^ WRAP_E : wrap | WRAP_W;
195 if (strchr("we", d) && yx->y > original.y)
197 wrap = wrap & WRAP_S ? wrap ^ WRAP_S : wrap | WRAP_N;
199 else if (strchr("xc", d) && yx->y < original.y)
201 wrap = wrap & WRAP_N ? wrap ^ WRAP_N : wrap | WRAP_S;
208 extern uint8_t mv_yx_in_dir_legal(char dir, struct yx_uint8 * yx)
210 uint8_t wraptest = mv_yx_in_dir_wrap(dir, yx, 0);
211 if (!wraptest && yx->x < world.map.size.x && yx->y < world.map.size.y)
220 static char next_circle_dir(uint8_t new_circle, uint8_t radius_new)
222 static uint8_t i_dirs = 0;
223 static uint8_t i_dist = 0;
224 static uint8_t radius = 0;
225 char * dirs = "dcxswe";
233 char ret_dir = dirs[i_dirs];
235 if (i_dist == radius)
245 extern void draw_border_circle(struct yx_uint8 yx, uint8_t radius,
249 for (dist = 1; dist <= radius; dist++)
251 mv_yx_in_dir_wrap('w', &yx, 0);
253 next_circle_dir(1, radius);
255 while ('\0' != (dir = next_circle_dir(0, 0)))
257 if (mv_yx_in_dir_legal(dir, &yx))
259 uint16_t pos = yx_to_map_pos(&yx);
260 fov_map[pos] = LIMIT;
263 mv_yx_in_dir_wrap(0, NULL, 1);
268 static void geometry_to_char_ratio(uint8_t * n1, uint8_t * n2, uint8_t indent,
269 int16_t diff_y, int16_t diff_x,
270 uint8_t vertical, uint8_t variant)
274 *n1 = (diff_y / 2) - diff_x + ( indent * (diff_y % 2));
275 *n2 = (diff_y / 2) + diff_x + (!indent * (diff_y % 2));
280 *n2 = diff_x - (diff_y / 2) - (indent * (diff_y % 2));
292 static char * eye_to_cell_dir_ratio(char * available_dirs, uint8_t indent,
293 int16_t diff_y, int16_t diff_x,
294 uint8_t vertical, uint8_t variant,
297 char * f_name = "eye_to_cell_dir_ratio()";
299 geometry_to_char_ratio(&n1, &n2, indent, diff_y, diff_x, vertical, variant);
300 uint8_t size_chars = n1 + n2;
301 char * dirs = try_malloc(size_chars + 1, f_name);
302 uint8_t n_strong_char = n1 / n2;
303 uint8_t more_char1 = 0 < n_strong_char;
304 n_strong_char = !more_char1 ? (n2 / n1) : n_strong_char;
306 uint8_t i_of_char = shift_right;
307 for (i = 0, i_alter = 0; i < size_chars; i++)
309 char dirchar = available_dirs[i_of_char];
310 if (more_char1 != i_of_char)
313 if (i_alter == n_strong_char)
316 i_of_char = !i_of_char;
321 i_of_char = !i_of_char;
332 static char * dir_from_delta(uint8_t indent, int16_t diff_y, int16_t diff_x)
334 int16_t double_x = 2 * diff_x;
335 int16_t indent_corrected_double_x_pos = double_x - indent + !indent;
336 int16_t indent_corrected_double_x_neg = -double_x - !indent + indent;
339 if (diff_y == double_x || diff_y == indent_corrected_double_x_pos)
343 if (diff_y == -double_x || diff_y == indent_corrected_double_x_neg)
347 if (diff_y < double_x || diff_y < indent_corrected_double_x_pos)
351 if (diff_y < -double_x || diff_y < indent_corrected_double_x_neg)
359 if (diff_y == double_x || diff_y == indent_corrected_double_x_pos)
363 if (diff_y == -double_x || diff_y == indent_corrected_double_x_neg)
367 if (diff_y > double_x || diff_y > indent_corrected_double_x_pos)
371 if (diff_y > -double_x || diff_y > indent_corrected_double_x_neg)
377 return 0 > diff_x ? "s" : "d";
382 static char * eye_to_cell(struct yx_uint8 * yx_eye, struct yx_uint8 * yx_cell,
385 int16_t diff_y = yx_cell->y - yx_eye->y;
386 int16_t diff_x = yx_cell->x - yx_eye->x;
387 uint8_t indent = yx_eye->y % 2;
388 char * dir = dir_from_delta(indent, diff_y, diff_x);
390 if (1 == strlen(dir))
394 else if (!strcmp(dir, "dc"))
396 dirs = eye_to_cell_dir_ratio(dir, indent, diff_y, diff_x, 0,0,right);
398 else if (!strcmp(dir, "xs"))
400 dirs = eye_to_cell_dir_ratio(dir, !indent, diff_y, -diff_x, 0,1,right);
402 else if (!strcmp(dir, "cx"))
404 dirs = eye_to_cell_dir_ratio(dir, indent, diff_y, diff_x, 1,0,right);
406 else if (!strcmp(dir, "sw"))
408 dirs = eye_to_cell_dir_ratio(dir, !indent, -diff_y, -diff_x, 0,0,right);
410 else if (!strcmp(dir, "ed"))
412 dirs = eye_to_cell_dir_ratio(dir, indent, -diff_y, diff_x, 0,1,right);
414 else if (!strcmp(dir, "we"))
416 dirs = eye_to_cell_dir_ratio(dir, indent, -diff_y, diff_x, 1,1,right);
423 static uint8_t is_top_left_shaded(uint16_t pos_a, uint16_t pos_b,
426 uint16_t start_last_row = world.map.size.x * (world.map.size.y - 1);
427 uint8_t a_on_left_or_bottom = 0 <= a_y_on_left
428 || (pos_a >= start_last_row);
429 uint8_t b_on_top_or_right = pos_b < world.map.size.x
430 || pos_b % world.map.size.x==world.map.size.x-1;
431 return pos_a != pos_b && b_on_top_or_right && a_on_left_or_bottom;
436 static void fill_shadow(struct yx_uint8 * yx_eye, struct yx_uint8 * yx_cell,
437 uint8_t * fov_map, uint16_t pos_a, uint16_t pos_b)
439 int16_t a_y_on_left = !(pos_a%world.map.size.x)? pos_a/world.map.size.x :-1;
440 int16_t b_y_on_left = !(pos_b%world.map.size.x)? pos_b/world.map.size.x :-1;
441 uint8_t top_left_shaded = is_top_left_shaded(pos_a, pos_b, a_y_on_left);
443 uint8_t y, x, in_shade;
444 for (y = 0; y < world.map.size.y; y++)
446 in_shade = (top_left_shaded || (b_y_on_left >= 0 && y > b_y_on_left))
447 && (a_y_on_left < 0 || y < a_y_on_left);
448 for (x = 0; x < world.map.size.x; x++)
450 pos = (y * world.map.size.x) + x;
451 if (yx_eye->y == yx_cell->y && yx_eye->x < yx_cell->x)
453 uint8_t val = fov_map[pos] & (SHADOW_LEFT | SHADOW_RIGHT);
454 in_shade = 0 < val ? 1 : in_shade;
456 else if (yx_eye->y == yx_cell->y && yx_eye->x > yx_cell->x)
458 uint8_t val = fov_map[pos] & (SHADOW_LEFT | SHADOW_RIGHT);
459 in_shade = 0 < val ? 0 : in_shade;
461 else if (yx_eye->y > yx_cell->y && y <= yx_cell->y)
463 in_shade = 0 < (fov_map[pos] & SHADOW_LEFT) ? 1 : in_shade;
464 in_shade = (fov_map[pos] & SHADOW_RIGHT) ? 0 : in_shade;
466 else if (yx_eye->y < yx_cell->y && y >= yx_cell->y)
468 in_shade = 0 < (fov_map[pos] & SHADOW_RIGHT) ? 1 : in_shade;
469 in_shade = (fov_map[pos] & SHADOW_LEFT) ? 0 : in_shade;
471 if (!(fov_map[pos] & (SHADOW_LEFT | SHADOW_RIGHT))
474 fov_map[pos] = fov_map[pos] | HIDDEN;
482 static uint16_t shadow_arm(struct yx_uint8 * yx_eye, struct yx_uint8 * yx_start,
483 uint8_t * fov_map, char dir, uint8_t flag,
486 struct yx_uint8 yx_border = *yx_start;
487 uint16_t pos = yx_to_map_pos(&yx_border);
488 if (mv_yx_in_dir_legal(dir, &yx_border))
490 uint8_t met_limit = 0;
492 char * dirs = eye_to_cell(yx_eye, &yx_border, shift_right);
493 yx_border = *yx_start;
494 while (!met_limit && mv_yx_in_dir_legal(dirs[i_dirs], &yx_border))
496 pos = yx_to_map_pos(&yx_border);
497 met_limit = fov_map[pos] & LIMIT;
498 fov_map[pos] = fov_map[pos] | flag;
499 i_dirs = dirs[i_dirs + 1] ? i_dirs + 1 : 0;
503 mv_yx_in_dir_wrap(0, NULL, 1);
509 static void shadow(struct yx_uint8 * yx_eye, struct yx_uint8 * yx_start,
510 uint8_t * fov_map, char dir_left, char dir_right)
512 uint16_t pos_a, pos_b, pos_start, i;
513 pos_a = shadow_arm(yx_eye, yx_start, fov_map, dir_left, SHADOW_LEFT, 0);
514 pos_b = shadow_arm(yx_eye, yx_start, fov_map, dir_right, SHADOW_RIGHT, 1);
515 pos_start = yx_to_map_pos(yx_start);
516 fov_map[pos_start] = fov_map[pos_start] | SHADOW_LEFT | SHADOW_RIGHT;
517 fill_shadow(yx_eye, yx_start, fov_map, pos_a, pos_b);
518 for (i = 0; i < world.map.size.y * world.map.size.x; i++)
520 if (fov_map[i] & (SHADOW_LEFT | SHADOW_RIGHT) && i != pos_start)
522 fov_map[i] = fov_map[i] | HIDE_LATER;
524 fov_map[i] = fov_map[i] ^ (fov_map[i] & SHADOW_LEFT);
525 fov_map[i] = fov_map[i] ^ (fov_map[i] & SHADOW_RIGHT);
532 static void set_view_of_cell_and_shadows(struct yx_uint8 * yx_cell,
533 struct yx_uint8 * yx_eye,
536 char * dirs = "dcxswe";
537 uint16_t pos = yx_to_map_pos(yx_cell);
538 if (!(fov_map[pos] & HIDDEN))
540 fov_map[pos] = fov_map[pos] | VISIBLE;
541 if ('X' == world.map.cells[pos])
543 uint8_t last_pos = strlen(dirs) - 1;
544 int16_t diff_y = yx_cell->y - yx_eye->y;
545 int16_t diff_x = yx_cell->x - yx_eye->x;
546 uint8_t indent = yx_eye->y % 2;
547 char * dir = dir_from_delta(indent, diff_y, diff_x);
548 uint8_t start_pos = strchr(dirs, dir[0]) - dirs;
549 char prev = start_pos > 0 ? dirs[start_pos - 1] : dirs[last_pos];
550 char next = start_pos < last_pos ? dirs[start_pos + 1] : dirs[0];
553 uint8_t end_pos = strchr(dirs, dir[1]) - dirs;
554 next = end_pos < last_pos ? dirs[end_pos + 1] : dirs[0];
556 shadow(yx_eye, yx_cell, fov_map, prev, next);
563 extern uint8_t * build_fov_map(struct MapObj * eye)
565 char * f_name = "build_fov_map()";
566 uint8_t radius = 2 * world.map.size.y;
567 uint32_t map_size = world.map.size.y * world.map.size.x;
568 struct yx_uint8 yx = eye->pos;
569 uint8_t * fov_map = try_malloc(map_size, f_name);
570 memset(fov_map, 0, map_size);
571 draw_border_circle(yx, radius, fov_map);
572 fov_map[yx_to_map_pos(&yx)] = VISIBLE;
574 for (dist = 1; dist <= radius; dist++)
576 uint8_t first_round = 1;
578 next_circle_dir(1, dist);
579 while ('\0' != (dir = next_circle_dir(0, 0)))
581 char i_dir = first_round ? 'e' : dir;
583 if (mv_yx_in_dir_legal(i_dir, &yx))
585 set_view_of_cell_and_shadows(&yx, &eye->pos, fov_map);
590 for (i = 0; i < world.map.size.y * world.map.size.x; i++)
592 if (fov_map[i] & HIDE_LATER)
594 fov_map[i] = fov_map[i] ^ (fov_map[i] & VISIBLE);