X-Git-Url: https://pd.if.org/git/?a=blobdiff_plain;f=hexagon.h;fp=hexagon.h;h=50665d058f87c05faaa42e11838688892485d86c;hb=8ca2b8a06b00066a20f744a61c9bcdd65949a344;hp=0000000000000000000000000000000000000000;hpb=5c48a06bc8649958e69013c53e925b83398ebc74;p=hexagon

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+#ifndef HEXLIB_H_
+#define HEXLIB_H_ 1
+
+/*
+ * this library implements a generic library for hexgrids for games.
+ * it avoids display issues, other than some general provisions
+ * for data
+ *
+ * This file is written by Nathan Wagner and dedicated to the
+ * public domain.
+ */
+
+/* max size for cantor numbers is 16383, or 32767 if non-negative,
+ * assuming a 32 bit int
+ */ 
+
+/* map from cartesian coordinates to hex coords */
+/* cartesian coordinates are positive Y up, hex coords
+ * are positive Y down.  You may need to pass in the
+ * negative of your Y coordinate
+ *
+ * width is the distance from one hexside to the opposite
+ * hexside.  i and j are the cartesian coordinates of the hex
+ * the x,y point falls in.  If a point happens to fall exactly
+ * on a hex boundary, the result will depend on how the machine
+ * does the floating point math, but should be consistent.
+ */
+int HL_hexbin(double width, double x, double y, int *i, int *j);
+
+/* generate the cantor mapping of a hexes x,y coordinate.
+ * See http://en.wikipedia.org/wiki/Cantor_pairing_function.
+ * We modify the basic formula to support negative coordinates
+ *
+ * The cantor mapping is *not* a contiguous mapping, as it maps
+ * onto a triangle, so you can't use the cantor mapping as
+ * an index into an array.  Or, you can, but the array
+ * will be (I think) twice as large as it needs to be
+ *
+ * See also http://mathworld.wolfram.com/PairingFunction.html
+ * for a reference to a square mapping by Stein that doesn't
+ * have this problem, at least for square maps.
+ *
+ * We use the cantor mapping so that the generated integer
+ * is independent of the size of the grid.
+ */
+
+/* Cartesian functions */
+int HL_cantor_xy(int x, int y);
+int HL_cantor_xyp(int *xy);
+int HL_cantor_x(int cantor);
+int HL_cantor_y(int cantor);
+
+/* Isometric functions */
+int HL_cantor_ijk(int i, int j, int k);
+int HL_cantor_ijkp(int *ijk);
+int HL_cantor_i(int cantor);
+int HL_cantor_k(int cantor);
+int HL_cantor_j(int cantor);
+
+int HL_cantor_bin(double x, double y);
+
+/* A general decode function */
+int HL_cantor_decode(int can, int *x, int *y, int *i, int *j, int *k);
+int HL_cantor_arrays(int can, int *xy, int *ijk);
+
+/*
+ * layout assistance functions
+ *
+ * HL_center_x(int cantor) returns the cartesian X coordinate
+ * of a given hex, assuming a width of 1.0.  Scaling can
+ * be done by the caller.
+ *
+ * Similarly for HL_center_y() and HL_hexcenter()
+ */
+double HL_center_x(int cantor);
+double HL_center_y(int cantor);
+int HL_hexcenter(int cantor, double *x, double *y);
+
+/* how far is it on the hex grid */
+int HL_distance(int from_cantor, int to_cantor);
+
+/* returns 0 for <0 or >5 */
+int HL_adjacent_hex(int start, int dir);
+
+/* module direction */
+int HL_adjhex(int start, int dir);
+int HL_hexes_at_range(int hex, int range, int *list, int size);
+int HL_hexes_within_range(int hex, int range, int *list, int size);
+
+typedef double (*HL_costfunc)(int start, int finish);
+
+/* writes up to len cantors to path.  returns last
+ * value written
+ * perhaps it should return the last value not written, if the
+ * path is incomplete?
+ * either way, it can then be used in a loop
+ */
+int HL_path(int start, int end, int *path, int len);
+
+int HL_map_bounds_ok(int xdim, int ydim);
+int HL_map_max_dimension(void);
+
+/*
+ * Plotting support
+ */
+void HL_trianglefan(int cantor, double *);
+
+struct HL_hex {
+	int x,y; /* hmm.  would be nice to be able to just point to a generic */
+};
+
+/*
+ * Pathfinding
+ */
+
+struct HL_astar_hex {
+	int hex;
+	double f, g, h;
+	struct HL_astar_hex *parent;
+	int	open;
+	struct HL_astar_hex *next;
+	struct HL_astar_hex *prev;
+};
+
+struct HL_astar {
+	int start, goal;
+	int pathlen;
+	double (*metric)(int,int);
+	double (*heuristic)(int,int);
+	int (*neighbor)(int,int);
+	int nodes, allocated;
+	struct HL_astar_hex *sets;
+	struct HL_astar_hex *open;
+	struct HL_astar_hex *closed;
+	struct HL_astar_hex *from, *to;
+	int known, index;
+	int error, malloced;
+};
+
+int HL_findpath(struct HL_astar *s, int loops);
+void HL_astar_free(struct HL_astar *s);
+struct HL_astar *HL_astar_clear(struct HL_astar *s);
+struct HL_astar *HL_astar_init(struct HL_astar *s);
+
+#endif