#include <stddef.h> /* NULL */
-#include <stdint.h> /* uint8_t, uint16_t, uint32_t, INT8_MIN, INT8_MAX */
+#include <stdint.h> /* ?(u)int(8|16|32)_t, ?(U)INT8_(MIN|MAX) */
+#include <stdlib.h> /* free, malloc */
+#include <string.h> /* memset */
+/* Number of degrees a circle is divided into. The greater it is, the greater
+ * the angle precision. But make it one whole zero larger and bizarre FOV bugs
+ * appear on large maps, probably due to value overflows (TODO: more research!).
+ */
+#define CIRCLE 3600000
+/* Angle of a shadow. */
+struct shadow_angle
+{
+ struct shadow_angle * next;
+ uint32_t left_angle;
+ uint32_t right_angle;
+};
+
+/* To be used as temporary storage for world map array. */
+static char * worldmap = NULL;
/* Coordinate for maps of max. 256x256 cells. */
struct yx_uint8
maplength = maplength_input;
}
-
-
/* Pseudo-randomness seed for rrand(), set by seed_rrand(). */
static uint32_t seed = 0;
-
-
/* Helper to mv_yx_in_dir_legal(). Move "yx" into hex direction "d". */
static void mv_yx_in_dir(char d, struct yx_uint8 * yx)
{
}
}
-
-
/* Move "yx" into hex direction "dir". Available hex directions are: 'e'
* (north-east), 'd' (east), 'c' (south-east), 'x' (south-west), 's' (west), 'w'
* (north-west). Returns 1 if the move was legal, 0 if not, and -1 when internal
return 0;
}
-
-
/* Wrapper around mv_yx_in_dir_legal() that stores new coordinate in res_y/x,
* (return with result_y/x()), and immediately resets the wrapping.
*/
return res_x;
}
-
-
/* With set_seed set, set seed global to seed_input. In any case, return it. */
extern uint32_t seed_rrand(uint8_t set_seed, uint32_t seed_input)
{
return seed;
}
-
-
/* Return 16-bit number pseudo-randomly generated via Linear Congruential
* Generator algorithm with some proven constants. Use instead of any rand() to
* ensure portability of the same pseudo-randomness across systems.
seed = ((seed * 1103515245) + 12345) % 4294967296;
return (seed >> 16); /* Ignore less random least significant bits. */
}
+
+/* Free shadow angles list "angles". */
+static void free_angles(struct shadow_angle * angles)
+{
+ if (angles->next)
+ {
+ free_angles(angles->next);
+ }
+ free(angles);
+}
+
+/* Recalculate angle < 0 or > CIRCLE to a value between these two limits. */
+static uint32_t correct_angle(int32_t angle)
+{
+ while (angle < 0)
+ {
+ angle = angle + CIRCLE;
+ }
+ while (angle > CIRCLE)
+ {
+ angle = angle - CIRCLE;
+ }
+ return angle;
+}
+
+/* Try merging the angle between "left_angle" and "right_angle" to "shadow" if
+ * it meets the shadow from the right or the left. Returns 1 on success, else 0.
+ */
+static uint8_t try_merge(struct shadow_angle * shadow,
+ uint32_t left_angle, uint32_t right_angle)
+{
+ if ( shadow->right_angle <= left_angle + 1
+ && shadow->right_angle >= right_angle)
+ {
+ shadow->right_angle = right_angle;
+ }
+ else if ( shadow->left_angle + 1 >= right_angle
+ && shadow->left_angle <= left_angle)
+ {
+ shadow->left_angle = left_angle;
+ }
+ else
+ {
+ return 0;
+ }
+ return 1;
+}
+
+/* Try merging the shadow angle between "left_angle" and "right_angle" into an
+ * existing shadow angle in "shadows". On success, see if this leads to any
+ * additional shadow angle overlaps and merge these accordingly. Return 1 on
+ * success, else 0.
+ */
+static uint8_t try_merging_angles(uint32_t left_angle, uint32_t right_angle,
+ struct shadow_angle ** shadows)
+{
+ uint8_t angle_merge = 0;
+ struct shadow_angle * shadow;
+ for (shadow = *shadows; shadow; shadow = shadow->next)
+ {
+ if (try_merge(shadow, left_angle, right_angle))
+ {
+ angle_merge = 1;
+ }
+ }
+ if (angle_merge)
+ {
+ struct shadow_angle * shadow1;
+ for (shadow1 = *shadows; shadow1; shadow1 = shadow1->next)
+ {
+ struct shadow_angle * last_shadow = NULL;
+ struct shadow_angle * shadow2;
+ for (shadow2 = *shadows; shadow2; shadow2 = shadow2->next)
+ {
+ if ( shadow1 != shadow2
+ && try_merge(shadow1, shadow2->left_angle,
+ shadow2->right_angle))
+ {
+ struct shadow_angle * to_free = shadow2;
+ if (last_shadow)
+ {
+ last_shadow->next = shadow2->next;
+ shadow2 = last_shadow;
+ }
+ else
+ {
+ *shadows = shadow2->next;
+ shadow2 = *shadows;
+ }
+ free(to_free);
+ }
+ last_shadow = shadow2;
+ }
+ }
+ }
+ return angle_merge;
+}
+
+/* To "shadows", add shadow defined by "left_angle" and "right_angle", either as
+ * new entry or as part of an existing shadow (swallowed whole or extending it).
+ * Return 1 on malloc error, else 0.
+ */
+static uint8_t set_shadow(uint32_t left_angle, uint32_t right_angle,
+ struct shadow_angle ** shadows)
+{
+ struct shadow_angle * shadow_i;
+ if (!try_merging_angles(left_angle, right_angle, shadows))
+ {
+ struct shadow_angle * shadow;
+ shadow = malloc(sizeof(struct shadow_angle));
+ if (!shadow)
+ {
+ return 1;
+ }
+ shadow->left_angle = left_angle;
+ shadow->right_angle = right_angle;
+ shadow->next = NULL;
+ if (*shadows)
+ {
+ for (shadow_i = *shadows; shadow_i; shadow_i = shadow_i->next)
+ {
+ if (!shadow_i->next)
+ {
+ shadow_i->next = shadow;
+ return 0;
+ }
+ }
+ }
+ *shadows = shadow;
+ }
+ return 0;
+}
+
+/* Test whether angle between "left_angle" and "right_angle", or at least
+ * "middle_angle", is captured inside one of the shadow angles in "shadows". If
+ * so, set hex in "fov_map" indexed by "pos_in_map" to 'H'. If the whole angle
+ * and not just "middle_angle" is captured, return 1. Any other case: 0.
+ */
+static uint8_t shade_hex(uint32_t left_angle, uint32_t right_angle,
+ uint32_t middle_angle, struct shadow_angle ** shadows,
+ uint16_t pos_in_map, char * fov_map)
+{
+ struct shadow_angle * shadow_i;
+ if (fov_map[pos_in_map] == 'v')
+ {
+ for (shadow_i = *shadows; shadow_i; shadow_i = shadow_i->next)
+ {
+ if ( left_angle <= shadow_i->left_angle
+ && right_angle >= shadow_i->right_angle)
+ {
+ fov_map[pos_in_map] = 'H';
+ return 1;
+ }
+ if ( middle_angle < shadow_i->left_angle
+ && middle_angle > shadow_i->right_angle)
+ {
+ fov_map[pos_in_map] = 'H';
+ }
+ }
+ }
+ return 0;
+}
+
+/* Evaluate map position "test_pos" in distance "dist" to the view origin, and
+ * on the circle of that distance to the origin on hex "hex_i" (as counted from
+ * the circle's rightmost point), for setting shaded hexes in "fov_map" and
+ * potentially adding a new shadow to linked shadow angle list "shadows".
+ * Return 1 on malloc error, else 0.
+ */
+static uint8_t eval_position(uint16_t dist, uint16_t hex_i, char * fov_map,
+ struct yx_uint8 * test_pos,
+ struct shadow_angle ** shadows)
+{
+ int32_t left_angle_uncorrected = ((CIRCLE / 12) / dist)
+ - (hex_i * (CIRCLE / 6) / dist);
+ int32_t right_angle_uncorrected = left_angle_uncorrected
+ - (CIRCLE / (6 * dist));
+ uint32_t left_angle = correct_angle(left_angle_uncorrected);
+ uint32_t right_angle = correct_angle(right_angle_uncorrected);
+ uint32_t right_angle_1st = right_angle > left_angle ? 0 : right_angle;
+ uint32_t middle_angle = 0;
+ if (right_angle_1st)
+ {
+ middle_angle = right_angle + ((left_angle - right_angle) / 2);
+ }
+ uint16_t pos_in_map = test_pos->y * maplength + test_pos->x;
+ uint8_t all_shaded = shade_hex(left_angle, right_angle_1st, middle_angle,
+ shadows, pos_in_map, fov_map);
+ if (!all_shaded && 'X' == worldmap[pos_in_map])
+ {
+ if (set_shadow(left_angle, right_angle_1st, shadows))
+ {
+ return 1;
+ }
+ if (right_angle_1st != right_angle)
+ {
+ left_angle = CIRCLE;
+ if (set_shadow(left_angle, right_angle, shadows))
+ {
+ return 1;
+ }
+ }
+ }
+ return 0;
+}
+
+/* Update field of view in "fovmap" of "worldmap_input" as seen from "y"/"x".
+ * Return 1 on malloc error, else 0.
+ */
+extern uint8_t build_fov_map(uint8_t y, uint8_t x,
+ char * fovmap, char * worldmap_input)
+{
+ worldmap = worldmap_input;
+ struct shadow_angle * shadows = NULL;
+ struct yx_uint8 test_pos;
+ test_pos.y = y;
+ test_pos.x = x;
+ char * circledirs_string = "xswedc";
+ uint16_t circle_i;
+ uint8_t circle_is_on_map;
+ for (circle_i = 1, circle_is_on_map = 1; circle_is_on_map; circle_i++)
+ {
+ circle_is_on_map = 0;
+ if (1 < circle_i) /* All circles but the 1st are */
+ { /* moved into starting from a */
+ mv_yx_in_dir_legal('c', &test_pos);/* previous circle's last hex, */
+ } /* i.e. from the upper left. */
+ char dir_char = 'd'; /* Circle's 1st hex is entered by rightward move.*/
+ uint8_t dir_char_pos_in_circledirs_string = UINT8_MAX;
+ uint16_t dist_i, hex_i;
+ for (hex_i=0, dist_i=circle_i; hex_i < 6 * circle_i; dist_i++, hex_i++)
+ {
+ if (circle_i < dist_i)
+ {
+ dist_i = 1;
+ dir_char=circledirs_string[++dir_char_pos_in_circledirs_string];
+ }
+ if (mv_yx_in_dir_legal(dir_char, &test_pos))
+ {
+ if (eval_position(circle_i, hex_i, fovmap, &test_pos, &shadows))
+ {
+ return 1;
+ }
+ circle_is_on_map = 1;
+ }
+ }
+ }
+ mv_yx_in_dir_legal(0, NULL);
+ free_angles(shadows);
+ return 0;
+}
projects / plomrogue / commitdiff