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