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/*
* (c) Lambros Lambrou 2008
*
* Code for working with general grids, which can be any planar graph
* with faces, edges and vertices (dots). Includes generators for a few
* types of grid, including square, hexagonal, triangular and others.
*/
#ifndef PUZZLES_GRID_H
#define PUZZLES_GRID_H
/* Useful macros */
#define SQ(x) ( (x) * (x) )
/* ----------------------------------------------------------------------
* Grid structures:
* A grid is made up of faces, edges and dots. These structures hold
* the incidence relationships between these types. For example, an
* edge always joins two dots, and is adjacent to two faces.
* The "grid_xxx **" members are lists of pointers which are dynamically
* allocated during grid generation.
* A pointer to a face/edge/dot will always point somewhere inside one of the
* three lists of the main "grid" structure: faces, edges, dots.
* Could have used integer offsets into these lists, but using actual
* pointers instead gives us type-safety.
*/
/* Need forward declarations */
typedef struct grid_face grid_face;
typedef struct grid_edge grid_edge;
typedef struct grid_dot grid_dot;
struct grid_face {
int order; /* Number of edges, also the number of dots */
grid_edge **edges; /* edges around this face */
grid_dot **dots; /* corners of this face */
};
struct grid_edge {
grid_dot *dot1, *dot2;
grid_face *face1, *face2; /* Use NULL for the infinite outside face */
};
struct grid_dot {
int order;
grid_edge **edges;
grid_face **faces; /* A NULL grid_face* means infinite outside face */
/* Position in some fairly arbitrary (Cartesian) coordinate system.
* Use large enough values such that we can get away with
* integer arithmetic, but small enough such that arithmetic
* won't overflow. */
int x, y;
};
typedef struct grid {
/* These are (dynamically allocated) arrays of all the
* faces, edges, dots that are in the grid. */
int num_faces; grid_face *faces;
int num_edges; grid_edge *edges;
int num_dots; grid_dot *dots;
/* Should be a face roughly near the middle of the grid.
* Used to seed path-generation, and also for nearest-edge
* detection. */
grid_face *middle_face;
/* Cache the bounding-box of the grid, so the drawing-code can quickly
* figure out the proper scaling to draw onto a given area. */
int lowest_x, lowest_y, highest_x, highest_y;
/* A measure of tile size for this grid (in grid coordinates), to help
* the renderer decide how large to draw the grid.
* Roughly the size of a single tile - for example the side-length
* of a square cell. */
int tilesize;
/* We really don't want to copy this monstrosity!
* A grid is immutable once generated.
*/
int refcount;
} grid;
grid *grid_new_square(int width, int height);
grid *grid_new_honeycomb(int width, int height);
grid *grid_new_triangular(int width, int height);
grid *grid_new_snubsquare(int width, int height);
grid *grid_new_cairo(int width, int height);
grid *grid_new_greathexagonal(int width, int height);
grid *grid_new_octagonal(int width, int height);
grid *grid_new_kites(int width, int height);
void grid_free(grid *g);
grid_edge *grid_nearest_edge(grid *g, int x, int y);
#endif /* PUZZLES_GRID_H */
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