+typedef struct _windstate
+{
+ char is_filled;
+ int wind_nr;
+ int num_polygons;
+} windstate_t;
+
+typedef struct _windrule
+{
+ windstate_t (*start)(int num_polygons);
+ windstate_t (*add)(windstate_t left, fillstyle_t*edge, segment_dir_t dir, int polygon_nr);
+ fillstyle_t* (*diff)(windstate_t*left, windstate_t*right);
+} windrule_t;
+