penrose.h

   1 /* penrose.h
   2  *
   3  * Penrose tiling functions.
   4  *
   5  * Provides an interface with which to generate Penrose tilings
   6  * by recursive subdivision of an initial tile of choice (one of the
   7  * four sets of two pairs kite/dart, or thin/thick rhombus).
   8  *
   9  * You supply a callback function and a context pointer, which is
  10  * called with each tile in turn: you choose how many times to recurse.
  11  */
  12
  13 #ifndef _PENROSE_H
  14 #define _PENROSE_H
  15
  16 #ifndef PHI
  17 #define PHI 1.6180339887
  18 #endif
  19
  20 typedef struct vector vector;
  21
  22 double v_x(vector *vs, int i);
  23 double v_y(vector *vs, int i);
  24
  25 typedef struct penrose_state penrose_state;
  26
  27 /* Return non-zero to clip the tree here (i.e. not recurse
  28  * below this tile).
  29  *
  30  * Parameters are state, vector array, npoints, depth.
  31  * ctx is inside state.
  32  */
  33 typedef int (*tile_callback)(penrose_state *, vector *, int, int);
  34
  35 struct penrose_state {
  36     int start_size;  /* initial side length */
  37     int max_depth;      /* Recursion depth */
  38
  39     tile_callback new_tile;
  40     void *ctx;          /* for callback */
  41 };
  42
  43 enum { PENROSE_P2, PENROSE_P3 };
  44
  45 extern int penrose(penrose_state *state, int which, int angle);
  46
  47 /* Returns the side-length of a penrose tile at recursion level
  48  * gen, given a starting side length. */
  49 extern double penrose_side_length(double start_size, int depth);
  50
  51 /* Returns the count of each type of tile at a given recursion depth. */
  52 extern void penrose_count_tiles(int gen, int *nlarge, int *nsmall);
  53
  54 /* Calculate start size and recursion depth required to produce a
  55  * width-by-height sized patch of penrose tiles with the given tilesize */
  56 extern void penrose_calculate_size(int which, int tilesize, int w, int h,
  57                                    double *required_radius, int *start_size, int *depth);
  58
  59 #endif