ref: 4752c7a2d9bd83d41d418b31b931a9bb9af219fa
dir: /hat.h/
#ifndef PUZZLES_HAT_H #define PUZZLES_HAT_H struct HatPatchParams { /* * A patch of hat tiling is identified by giving the coordinates * of the kite in one corner, using a multi-level coordinate * system based on metatile expansions. Coordinates are a sequence * of small non-negative integers. The valid range for each * coordinate depends on the next coordinate, or on final_metatile * if it's the last one in the list. The largest valid range is * {0,...,12}. * * 'final_metatile' is one of the characters 'H', 'T', 'P' or 'F'. */ size_t ncoords; unsigned char *coords; char final_metatile; }; /* * Fill in HatPatchParams with a randomly selected set of coordinates, * in enough detail to generate a patch of tiling covering an area of * w x h 'squares' of a kite tiling. * * The kites grid is considered to be oriented so that it includes * horizontal lines and not vertical ones. So each of the smallest * equilateral triangles in the grid has a bounding rectangle whose * height is sqrt(3)/2 times its width, and either the top or the * bottom of that bounding rectangle is the horizontal edge of the * triangle. A 'square' of a kite tiling (for convenience of choosing * grid dimensions) counts as one of those bounding rectangles. * * The 'coords' field of the structure will be filled in with a new * dynamically allocated array. Any previous pointer in that field * will be overwritten. */ void hat_tiling_randomise(struct HatPatchParams *params, int w, int h, random_state *rs); /* * Validate a HatPatchParams to ensure it contains no illegal * coordinates. Returns NULL if it's acceptable, or an error string if * not. */ const char *hat_tiling_params_invalid(const struct HatPatchParams *params); /* * Generate the actual set of hat tiles from a HatPatchParams, passing * each one to a callback. The callback receives the vertices of each * point, as a sequence of 2*nvertices integers, with x,y coordinates * interleaved. * * The x coordinates are measured in units of 1/4 of the side length * of the smallest equilateral triangle, or equivalently, 1/2 the * length of one of the long edges of a single kite. The y coordinates * are measured in units of 1/6 the height of the triangle, which is * also 1/2 the length of the short edge of a kite. Therefore, you can * expect x to go up to 4*w and y up to 6*h. */ typedef void (*hat_tile_callback_fn)(void *ctx, size_t nvertices, int *coords); void hat_tiling_generate(const struct HatPatchParams *params, int w, int h, hat_tile_callback_fn cb, void *cbctx); #endif