lib/gfxpoly/wind.c

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