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
  64         return &edgestyle_default;
  65 }
  66
  67 windrule_t windrule_circular = {
  68     start: circular_start,
  69     add: circular_add,
  70     diff: circular_diff,
  71 };
  72
  73 // -------------------- intersect ----------------------
  74
  75 windstate_t intersect_start(windcontext_t*context)
  76 {
  77     return windstate_nonfilled;
  78 }
  79
  80 windstate_t intersect_add(windcontext_t*context, windstate_t left, edgestyle_t*edge, segment_dir_t dir, int master)
  81 {
  82     assert(master < context->num_polygons);
  83
  84     left.wind_nr ^= 1<<master;
  85     left.is_filled = (left.wind_nr == (1<<context->num_polygons)-1);
  86     return left;
  87 }
  88
  89 edgestyle_t* intersect_diff(windstate_t*left, windstate_t*right)
  90 {
  91     if(left->is_filled==right->is_filled)
  92         return 0;
  93     else
  94         return &edgestyle_default;
  95 }
  96
  97 windrule_t windrule_intersect = {
  98     start: intersect_start,
  99     add: intersect_add,
 100     diff: intersect_diff,
 101 };
 102
 103 // -------------------- union ----------------------
 104
 105 windstate_t union_start(windcontext_t*context)
 106 {
 107     return windstate_nonfilled;
 108 }
 109
 110 windstate_t union_add(windcontext_t*context, windstate_t left, edgestyle_t*edge, segment_dir_t dir, int master)
 111 {
 112     assert(master<sizeof(left.wind_nr)*8); //up to 32/64 polygons max
 113     left.wind_nr ^= 1<<master;
 114     left.is_filled = (left.wind_nr!=0);
 115     return left;
 116 }
 117
 118 edgestyle_t* union_diff(windstate_t*left, windstate_t*right)
 119 {
 120     if(left->is_filled==right->is_filled)
 121         return 0;
 122     else
 123         return &edgestyle_default;
 124 }
 125
 126 windrule_t windrule_union = {
 127     start: union_start,
 128     add: union_add,
 129     diff: union_diff,
 130 };
 131
 132
 133 /*
 134  } else if (rule == WIND_NONZERO) {
 135      fill = wind!=0;
 136  } else if (rule == WIND_ODDEVEN) {
 137      fill = wind&1;
 138  } else { // rule == WIND_POSITIVE
 139      fill = wind>=1;
 140  }
 141  */