lib/gfxpoly/wind.c

   1 #include <assert.h>
   2 #include "wind.h"
   3
   4 fillstyle_t fillstyle_default;
   5
   6 windstate_t windstate_nonfilled = {
   7     is_filled: 0,
   8     wind_nr: 0,
   9
  10     /* TODO: move num_polygons into windstate_t.internal */
  11     num_polygons: 1,
  12 };
  13
  14 // -------------------- even/odd ----------------------
  15
  16 windstate_t evenodd_start(int num_polygons)
  17 {
  18     return windstate_nonfilled;
  19 }
  20 windstate_t evenodd_add(windstate_t left, fillstyle_t*edge, segment_dir_t dir, int master)
  21 {
  22     left.is_filled ^= 1;
  23     return left;
  24 }
  25 fillstyle_t* evenodd_diff(windstate_t*left, windstate_t*right)
  26 {
  27     if(left->is_filled==right->is_filled)
  28         return 0;
  29     else
  30         return &fillstyle_default;
  31 }
  32
  33 windrule_t windrule_evenodd = {
  34     start: evenodd_start,
  35     add: evenodd_add,
  36     diff: evenodd_diff,
  37 };
  38
  39 // -------------------- circular ----------------------
  40
  41 windstate_t circular_start(int num_polygons)
  42 {
  43     return windstate_nonfilled;
  44 }
  45
  46 windstate_t circular_add(windstate_t left, fillstyle_t*edge, segment_dir_t dir, int master)
  47 {
  48     /* which one is + and which one - doesn't actually make any difference */
  49     if(dir == DIR_DOWN)
  50         left.wind_nr++;
  51     else
  52         left.wind_nr--;
  53
  54     left.is_filled = left.wind_nr != 0;
  55     return left;
  56 }
  57
  58 fillstyle_t* circular_diff(windstate_t*left, windstate_t*right)
  59 {
  60     if(left->is_filled==right->is_filled)
  61         return 0;
  62     else
  63         return &fillstyle_default;
  64 }
  65
  66 windrule_t windrule_circular = {
  67     start: circular_start,
  68     add: circular_add,
  69     diff: circular_diff,
  70 };
  71
  72 // -------------------- intersect ----------------------
  73
  74 windstate_t intersect_start(int num_polygons)
  75 {
  76     windstate_t w;
  77     w.num_polygons = num_polygons;
  78     return w;
  79 }
  80
  81 windstate_t intersect_add(windstate_t left, fillstyle_t*edge, segment_dir_t dir, int master)
  82 {
  83     assert(master < left.num_polygons);
  84
  85     left.wind_nr ^= 1<<master;
  86     if(left.wind_nr == (1<<left.num_polygons)-1)
  87         left.is_filled = 1;
  88     return left;
  89 }
  90
  91 fillstyle_t* intersect_diff(windstate_t*left, windstate_t*right)
  92 {
  93     if(left->is_filled==right->is_filled)
  94         return 0;
  95     else
  96         return &fillstyle_default;
  97 }
  98
  99 windrule_t windrule_intersect = {
 100     start: intersect_start,
 101     add: intersect_add,
 102     diff: intersect_diff,
 103 };
 104
 105 // -------------------- union ----------------------
 106
 107 windstate_t union_start(int num_polygons)
 108 {
 109     return windstate_nonfilled;
 110 }
 111
 112 windstate_t union_add(windstate_t left, fillstyle_t*edge, segment_dir_t dir, int master)
 113 {
 114     assert(master<sizeof(left.wind_nr)*8); //up to 32/64 polygons max
 115     left.wind_nr ^= 1<<master;
 116     if(left.wind_nr!=0)
 117         left.is_filled = 1;
 118     return left;
 119 }
 120
 121 fillstyle_t* union_diff(windstate_t*left, windstate_t*right)
 122 {
 123     if(left->is_filled==right->is_filled)
 124         return 0;
 125     else
 126         return &fillstyle_default;
 127 }
 128
 129 windrule_t windrule_union = {
 130     start: union_start,
 131     add: union_add,
 132     diff: union_diff,
 133 };
 134
 135
 136 /*
 137  } else if (rule == WIND_NONZERO) {
 138      fill = wind!=0;
 139  } else if (rule == WIND_ODDEVEN) {
 140      fill = wind&1;
 141  } else { // rule == WIND_POSITIVE
 142      fill = wind>=1;
 143  }
 144  */