| 1 | /* |
| 2 | * (c) Lambros Lambrou 2008 |
| 3 | * |
| 4 | * Code for working with general grids, which can be any planar graph |
| 5 | * with faces, edges and vertices (dots). Includes generators for a few |
| 6 | * types of grid, including square, hexagonal, triangular and others. |
| 7 | */ |
| 8 | |
| 9 | #ifndef PUZZLES_GRID_H |
| 10 | #define PUZZLES_GRID_H |
| 11 | |
| 12 | /* Useful macros */ |
| 13 | #define SQ(x) ( (x) * (x) ) |
| 14 | |
| 15 | /* ---------------------------------------------------------------------- |
| 16 | * Grid structures: |
| 17 | * A grid is made up of faces, edges and dots. These structures hold |
| 18 | * the incidence relationships between these types. For example, an |
| 19 | * edge always joins two dots, and is adjacent to two faces. |
| 20 | * The "grid_xxx **" members are lists of pointers which are dynamically |
| 21 | * allocated during grid generation. |
| 22 | * A pointer to a face/edge/dot will always point somewhere inside one of the |
| 23 | * three lists of the main "grid" structure: faces, edges, dots. |
| 24 | * Could have used integer offsets into these lists, but using actual |
| 25 | * pointers instead gives us type-safety. |
| 26 | */ |
| 27 | |
| 28 | /* Need forward declarations */ |
| 29 | typedef struct grid_face grid_face; |
| 30 | typedef struct grid_edge grid_edge; |
| 31 | typedef struct grid_dot grid_dot; |
| 32 | |
| 33 | struct grid_face { |
| 34 | int order; /* Number of edges, also the number of dots */ |
| 35 | grid_edge **edges; /* edges around this face */ |
| 36 | grid_dot **dots; /* corners of this face */ |
| 37 | }; |
| 38 | struct grid_edge { |
| 39 | grid_dot *dot1, *dot2; |
| 40 | grid_face *face1, *face2; /* Use NULL for the infinite outside face */ |
| 41 | }; |
| 42 | struct grid_dot { |
| 43 | int order; |
| 44 | grid_edge **edges; |
| 45 | grid_face **faces; /* A NULL grid_face* means infinite outside face */ |
| 46 | |
| 47 | /* Position in some fairly arbitrary (Cartesian) coordinate system. |
| 48 | * Use large enough values such that we can get away with |
| 49 | * integer arithmetic, but small enough such that arithmetic |
| 50 | * won't overflow. */ |
| 51 | int x, y; |
| 52 | }; |
| 53 | typedef struct grid { |
| 54 | /* These are (dynamically allocated) arrays of all the |
| 55 | * faces, edges, dots that are in the grid. */ |
| 56 | int num_faces; grid_face *faces; |
| 57 | int num_edges; grid_edge *edges; |
| 58 | int num_dots; grid_dot *dots; |
| 59 | |
| 60 | /* Should be a face roughly near the middle of the grid. |
| 61 | * Used to seed path-generation, and also for nearest-edge |
| 62 | * detection. */ |
| 63 | grid_face *middle_face; |
| 64 | |
| 65 | /* Cache the bounding-box of the grid, so the drawing-code can quickly |
| 66 | * figure out the proper scaling to draw onto a given area. */ |
| 67 | int lowest_x, lowest_y, highest_x, highest_y; |
| 68 | |
| 69 | /* A measure of tile size for this grid (in grid coordinates), to help |
| 70 | * the renderer decide how large to draw the grid. |
| 71 | * Roughly the size of a single tile - for example the side-length |
| 72 | * of a square cell. */ |
| 73 | int tilesize; |
| 74 | |
| 75 | /* We really don't want to copy this monstrosity! |
| 76 | * A grid is immutable once generated. |
| 77 | */ |
| 78 | int refcount; |
| 79 | } grid; |
| 80 | |
| 81 | grid *grid_new_square(int width, int height); |
| 82 | grid *grid_new_honeycomb(int width, int height); |
| 83 | grid *grid_new_triangular(int width, int height); |
| 84 | grid *grid_new_snubsquare(int width, int height); |
| 85 | grid *grid_new_cairo(int width, int height); |
| 86 | grid *grid_new_greathexagonal(int width, int height); |
| 87 | grid *grid_new_octagonal(int width, int height); |
| 88 | grid *grid_new_kites(int width, int height); |
| 89 | |
| 90 | void grid_free(grid *g); |
| 91 | |
| 92 | grid_edge *grid_nearest_edge(grid *g, int x, int y); |
| 93 | |
| 94 | #endif /* PUZZLES_GRID_H */ |