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* Penrose tiling functions.
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* Provides an interface with which to generate Penrose tilings
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* by recursive subdivision of an initial tile of choice (one of the
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* four sets of two pairs kite/dart, or thin/thick rhombus).
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* You supply a callback function and a context pointer, which is
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* called with each tile in turn: you choose how many times to recurse.
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#define PHI 1.6180339887
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typedef struct vector vector;
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double v_x(vector *vs, int i);
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double v_y(vector *vs, int i);
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typedef struct penrose_state penrose_state;
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/* Return non-zero to clip the tree here (i.e. not recurse
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* Parameters are state, vector array, npoints, depth.
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* ctx is inside state.
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typedef int (*tile_callback)(penrose_state *, vector *, int, int);
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struct penrose_state {
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int start_size; /* initial side length */
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int max_depth; /* Recursion depth */
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tile_callback new_tile;
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void *ctx; /* for callback */
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enum { PENROSE_P2, PENROSE_P3 };
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extern int penrose(penrose_state *state, int which, int angle);
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/* Returns the side-length of a penrose tile at recursion level
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* gen, given a starting side length. */
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extern double penrose_side_length(double start_size, int depth);
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/* Returns the count of each type of tile at a given recursion depth. */
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extern void penrose_count_tiles(int gen, int *nlarge, int *nsmall);
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/* Calculate start size and recursion depth required to produce a
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* width-by-height sized patch of penrose tiles with the given tilesize */
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extern void penrose_calculate_size(int which, int tilesize, int w, int h,
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double *required_radius, int *start_size, int *depth);