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 windstate_t circular_start(windcontext_t*context)
  39 {
  40     return windstate_nonfilled;
  41 }
  42
  43 windstate_t circular_add(windcontext_t*context, windstate_t left, edgestyle_t*edge, segment_dir_t dir, int master)
  44 {
  45     assert(edge);
  46     /* which one is + and which one - doesn't actually make any difference */
  47     if(dir == DIR_DOWN)
  48         left.wind_nr++;
  49     else
  50         left.wind_nr--;
  51
  52     left.is_filled = left.wind_nr != 0;
  53     return left;
  54 }
  55
  56 edgestyle_t* circular_diff(windstate_t*left, windstate_t*right)
  57 {
  58     if(left->is_filled==right->is_filled)
  59         return 0;
  60     else
  61         return &edgestyle_default;
  62 }
  63
  64 windrule_t windrule_circular = {
  65     start: circular_start,
  66     add: circular_add,
  67     diff: circular_diff,
  68 };
  69
  70 // -------------------- intersect ----------------------
  71
  72 windstate_t intersect_start(windcontext_t*context)
  73 {
  74     return windstate_nonfilled;
  75 }
  76
  77 windstate_t intersect_add(windcontext_t*context, windstate_t left, edgestyle_t*edge, segment_dir_t dir, int master)
  78 {
  79     assert(master < context->num_polygons);
  80
  81     left.wind_nr ^= 1<<master;
  82     left.is_filled = (left.wind_nr == (1<<context->num_polygons)-1);
  83     return left;
  84 }
  85
  86 edgestyle_t* intersect_diff(windstate_t*left, windstate_t*right)
  87 {
  88     if(left->is_filled==right->is_filled)
  89         return 0;
  90     else
  91         return &edgestyle_default;
  92 }
  93
  94 windrule_t windrule_intersect = {
  95     start: intersect_start,
  96     add: intersect_add,
  97     diff: intersect_diff,
  98 };
  99
 100 // -------------------- union ----------------------
 101
 102 windstate_t union_start(windcontext_t*context)
 103 {
 104     return windstate_nonfilled;
 105 }
 106
 107 windstate_t union_add(windcontext_t*context, windstate_t left, edgestyle_t*edge, segment_dir_t dir, int master)
 108 {
 109     assert(master<sizeof(left.wind_nr)*8); //up to 32/64 polygons max
 110     left.wind_nr ^= 1<<master;
 111     left.is_filled = (left.wind_nr!=0);
 112     return left;
 113 }
 114
 115 edgestyle_t* union_diff(windstate_t*left, windstate_t*right)
 116 {
 117     if(left->is_filled==right->is_filled)
 118         return 0;
 119     else
 120         return &edgestyle_default;
 121 }
 122
 123 windrule_t windrule_union = {
 124     start: union_start,
 125     add: union_add,
 126     diff: union_diff,
 127 };
 128
 129
 130 /*
 131  } else if (rule == WIND_NONZERO) {
 132      fill = wind!=0;
 133  } else if (rule == WIND_ODDEVEN) {
 134      fill = wind&1;
 135  } else { // rule == WIND_POSITIVE
 136      fill = wind>=1;
 137  }
 138  */