lib/gfxpoly/wind.c

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