tsiry-sandratraina.com
A modern Music Player Daemon based on Rockbox open source high quality audio player
libadwaita
audio
rust
zig
deno
mpris
rockbox
mpd
1#ifndef PUZZLES_PENROSE_H
2#define PUZZLES_PENROSE_H
3
4struct PenrosePatchParams {
5 /*
6 * A patch of Penrose tiling is identified by giving
7 *
8 * - the coordinates of the starting triangle, using a
9 * combinatorial coordinate system
10 *
11 * - which vertex of that triangle is at the centre point of the
12 * tiling
13 *
14 * - the orientation of the triangle's base edge, as a number
15 * from 0 to 9, measured in tenths of a turn
16 *
17 * Coordinates are a sequence of letters. For a P2 tiling all
18 * letters are from the set {A,B,U,V}; for P3, {C,D,X,Y}.
19 */
20 unsigned start_vertex;
21 int orientation;
22 size_t ncoords;
23 char *coords;
24};
25
26#ifndef PENROSE_ENUM_DEFINED
27#define PENROSE_ENUM_DEFINED
28enum { PENROSE_P2, PENROSE_P3 };
29#endif
30
31bool penrose_valid_letter(char c, int which);
32
33/*
34 * Fill in PenrosePatchParams with a randomly selected set of
35 * coordinates, in enough detail to generate a patch of tiling filling
36 * a w x h area.
37 *
38 * Units of measurement: the tiling will be oriented such that
39 * horizontal tile edges are possible (and therefore vertical ones are
40 * not). Therefore, all x-coordinates will be rational linear
41 * combinations of 1 and sqrt(5), and all y-coordinates will be
42 * sin(pi/5) times such a rational linear combination. By scaling up
43 * appropriately we can turn those rational combinations into
44 * _integer_ combinations, so we do. Therefore, w is measured in units
45 * of 1/4, and h is measured in units of sin(pi/5)/2, on a scale where
46 * a length of 1 corresponds to the legs of the acute isosceles
47 * triangles in the tiling (hence, the long edges of P2 kites and
48 * darts, or all edges of P3 rhombs).
49 *
50 * (In case it's useful, the y scale factor sin(pi/5)/2 is an
51 * algebraic number. Its minimal polynomial is 256x^4 - 80x^2 + 5.)
52 *
53 * The 'coords' field of the structure will be filled in with a new
54 * dynamically allocated array. Any previous pointer in that field
55 * will be overwritten.
56 */
57void penrose_tiling_randomise(struct PenrosePatchParams *params, int which,
58 int w, int h, random_state *rs);
59
60/*
61 * Validate a PenrosePatchParams to ensure it contains no illegal
62 * coordinates. Returns NULL if it's acceptable, or an error string if
63 * not.
64 */
65const char *penrose_tiling_params_invalid(
66 const struct PenrosePatchParams *params, int which);
67
68/*
69 * Generate the actual set of Penrose tiles from a PenrosePatchParams,
70 * passing each one to a callback. The callback receives the vertices
71 * of each point, in the form of an array of 4*4 integers. Each vertex
72 * is represented by four consecutive integers in this array, with the
73 * first two giving the x coordinate and the last two the y
74 * coordinate. Each pair of integers a,b represent a single coordinate
75 * whose value is a + b*sqrt(5). The units of measurement for x and y
76 * are as described above.
77 */
78typedef void (*penrose_tile_callback_fn)(void *ctx, const int *coords);
79
80#define PENROSE_NVERTICES 4
81
82void penrose_tiling_generate(
83 const struct PenrosePatchParams *params, int w, int h,
84 penrose_tile_callback_fn cb, void *cbctx);
85
86#endif