made gfxpoly_dump print out segments in the right order
[swftools.git] / lib / gfxpoly / poly.c
index d2c5295..7eb6509 100644 (file)
@@ -3,13 +3,13 @@
 #include <math.h>
 #include "../mem.h"
 #include "../types.h"
-#include "../q.h"
 #include "../MD5.h"
 #include "poly.h"
 #include "active.h"
 #include "xrow.h"
 #include "wind.h"
 #include "convert.h"
+#include "heap.h"
 
 static gfxpoly_t*current_polygon = 0;
 void gfxpoly_fail(char*expr, char*file, int line, const char*function)
@@ -19,7 +19,7 @@ void gfxpoly_fail(char*expr, char*file, int line, const char*function)
        exit(1);
     }
 
-    void*md5 = init_md5();
+    void*md5 = initialize_md5();
    
     int s,t;
     gfxpolystroke_t*stroke = current_polygon->strokes;
@@ -68,29 +68,13 @@ static void point_free(void*o)
     p->y = 0;
     free(p);
 }
-static type_t point_type = {
+type_t point_type = {
     equals: point_equals,
     hash: point_hash,
     dup: point_dup,
     free: point_free,
 };
 
-typedef struct _status {
-    int32_t y;
-    actlist_t*actlist;
-    heap_t*queue;
-    xrow_t*xrow;
-    windrule_t*windrule;
-    windcontext_t*context;
-    segment_t*ending_segments;
-    polywriter_t writer;
-#ifdef CHECKS
-    dict_t*seen_crossings; //list of crossing we saw so far
-    dict_t*intersecting_segs; //list of segments intersecting in this scanline
-    dict_t*segs_with_point; //lists of segments that received a point in this scanline
-#endif
-} status_t;
-
 typedef struct _event {
     eventtype_t type;
     point_t p;
@@ -101,7 +85,7 @@ typedef struct _event {
 /* compare_events_simple differs from compare_events in that it schedules
    events from left to right regardless of type. It's only used in horizontal
    processing, in order to get an x-wise sorting of the current scanline */
-static int compare_events_simple(const void*_a,const void*_b)
+static inline int compare_events_simple(const void*_a,const void*_b)
 {
     event_t* a = (event_t*)_a;
     event_t* b = (event_t*)_b;
@@ -112,7 +96,7 @@ static int compare_events_simple(const void*_a,const void*_b)
     return 0;
 }
 
-static int compare_events(const void*_a,const void*_b)
+static inline int compare_events(const void*_a,const void*_b)
 {
     event_t* a = (event_t*)_a;
     event_t* b = (event_t*)_b;
@@ -138,6 +122,38 @@ static int compare_events(const void*_a,const void*_b)
     //return d;
 }
 
+#define COMPARE_EVENTS(x,y) (compare_events(x,y)>0)
+#define COMPARE_EVENTS_SIMPLE(x,y) (compare_events_simple(x,y)>0)
+HEAP_DEFINE(queue,event_t,COMPARE_EVENTS);
+HEAP_DEFINE(hqueue,event_t,COMPARE_EVENTS_SIMPLE);
+
+typedef struct _status {
+    int32_t y;
+    actlist_t*actlist;
+    queue_t queue;
+    xrow_t*xrow;
+    windrule_t*windrule;
+    windcontext_t*context;
+    segment_t*ending_segments;
+
+    gfxpolystroke_t*strokes;
+#ifdef CHECKS
+    dict_t*seen_crossings; //list of crossing we saw so far
+    dict_t*intersecting_segs; //list of segments intersecting in this scanline
+    dict_t*segs_with_point; //lists of segments that received a point in this scanline
+#endif
+} status_t;
+
+
+int gfxpoly_num_segments(gfxpoly_t*poly)
+{
+    gfxpolystroke_t*stroke = poly->strokes;
+    int count = 0;
+    for(;stroke;stroke=stroke->next) {
+       count++;
+    }
+    return count;
+}
 int gfxpoly_size(gfxpoly_t*poly)
 {
     int s,t;
@@ -151,10 +167,17 @@ int gfxpoly_size(gfxpoly_t*poly)
 
 char gfxpoly_check(gfxpoly_t*poly)
 {
+    current_polygon = poly;
     dict_t*d = dict_new2(&point_type);
     int s,t;
     gfxpolystroke_t*stroke = poly->strokes;
     for(;stroke;stroke=stroke->next) {
+       /* In order to not confuse the fill/wind logic, existing segments must have
+          a non-zero edge style */
+       assert(stroke->fs);
+
+       /* put all the segments into dictionaries so that we can check
+          that the endpoint multiplicity is two */
        for(s=0;s<stroke->num_points;s++) {
            point_t p = stroke->points[s];
            int num = (s>=1 && s<stroke->num_points-1)?2:1; // mid points are two points (start+end)
@@ -171,9 +194,9 @@ char gfxpoly_check(gfxpoly_t*poly)
     DICT_ITERATE_ITEMS(d, point_t*, p, void*, c) {
         int count = (ptroff_t)c;
         if(count&1) {
-            fprintf(stderr, "Point (%f,%f) occurs %d times\n", p->x*poly->gridsize, p->y*poly->gridsize, count);
+            fprintf(stderr, "Point (%d,%d) occurs %d times\n", p->x, p->y, count);
             dict_destroy(d);
-            return 0;
+           assert(count%2 == 0);
         }
     }
     dict_destroy(d);
@@ -184,14 +207,24 @@ void gfxpoly_dump(gfxpoly_t*poly)
 {
     int s,t;
     double g = poly->gridsize;
-    fprintf(stderr, "polyon %08x (gridsize: %f)\n", poly, poly->gridsize);
+    fprintf(stderr, "polyon %p (gridsize: %f)\n", poly, poly->gridsize);
     gfxpolystroke_t*stroke = poly->strokes;
     for(;stroke;stroke=stroke->next) {
-       for(s=0;s<stroke->num_points-1;s++) {
-           point_t a = stroke->points[s];
-           point_t b = stroke->points[s+1];
-           fprintf(stderr, "%s(%f,%f) -> (%f,%f)%s\n", s?" ":"[", a.x*g, a.y*g, b.x*g, b.y*g,
-                                                       s==stroke->num_points-2?"]":"");
+       fprintf(stderr, "%11p", stroke);
+       if(stroke->dir==DIR_UP) {
+           for(s=stroke->num_points-1;s>=1;s--) {
+               point_t a = stroke->points[s];
+               point_t b = stroke->points[s-1];
+               fprintf(stderr, "%s (%f,%f) -> (%f,%f)%s%s\n", s!=stroke->num_points-1?"           ":"", a.x*g, a.y*g, b.x*g, b.y*g,
+                                                           s==1?"]":"", a.y==b.y?"H":"");
+           }
+       } else {
+           for(s=0;s<stroke->num_points-1;s++) {
+               point_t a = stroke->points[s];
+               point_t b = stroke->points[s+1];
+               fprintf(stderr, "%s (%f,%f) -> (%f,%f)%s%s\n", s?"           ":"", a.x*g, a.y*g, b.x*g, b.y*g,
+                                                           s==stroke->num_points-2?"]":"", a.y==b.y?"H":"");
+           }
        }
     }
 }
@@ -204,49 +237,52 @@ void gfxpoly_save(gfxpoly_t*poly, const char*filename)
     int s,t;
     gfxpolystroke_t*stroke = poly->strokes;
     for(;stroke;stroke=stroke->next) {
-       for(s=0;s<stroke->num_points-1;s++) {
-           point_t a = stroke->points[s];
-           point_t b = stroke->points[s+1];
            fprintf(fi, "%g setgray\n", stroke->dir==DIR_UP ? 0.7 : 0);
-           fprintf(fi, "%d %d moveto\n", a.x, a.y);
-           fprintf(fi, "%d %d lineto\n", b.x, b.y);
-           fprintf(fi, "stroke\n");
+       point_t p = stroke->points[0];
+       fprintf(fi, "%d %d moveto\n", p.x, p.y);
+       for(s=1;s<stroke->num_points;s++) {
+           p = stroke->points[s];
+           fprintf(fi, "%d %d lineto\n", p.x, p.y);
        }
+       fprintf(fi, "stroke\n");
     }
     fprintf(fi, "showpage\n");
     fclose(fi);
 }
 
-inline static event_t event_new()
+inline static event_t* event_new()
 {
-    event_t e;
-    memset(&e, 0, sizeof(e));
+    event_t*e = rfx_calloc(sizeof(event_t));
     return e;
 }
+inline static void event_free(event_t*e)
+{
+    free(e);
+}
 
 static void event_dump(event_t*e)
 {
     if(e->type == EVENT_HORIZONTAL) {
-        fprintf(stderr, "Horizontal [%d] (%d,%d) -> (%d,%d)\n", e->s1->nr, e->s1->a.x, e->s1->a.y, e->s1->b.x, e->s1->b.y);
+        fprintf(stderr, "Horizontal [%d] (%d,%d) -> (%d,%d)\n", (int)e->s1->nr, e->s1->a.x, e->s1->a.y, e->s1->b.x, e->s1->b.y);
     } else if(e->type == EVENT_START) {
-        fprintf(stderr, "event: segment [%d] starts at (%d,%d)\n", e->s1->nr, e->p.x, e->p.y);
+        fprintf(stderr, "event: segment [%d] starts at (%d,%d)\n", (int)e->s1->nr, e->p.x, e->p.y);
     } else if(e->type == EVENT_END) {
-        fprintf(stderr, "event: segment [%d] ends at (%d,%d)\n", e->s1->nr, e->p.x, e->p.y);
+        fprintf(stderr, "event: segment [%d] ends at (%d,%d)\n", (int)e->s1->nr, e->p.x, e->p.y);
     } else if(e->type == EVENT_CROSS) {
-        fprintf(stderr, "event: segment [%d] and [%d] intersect at (%d,%d)\n", e->s1->nr, e->s2->nr, e->p.x, e->p.y);
+        fprintf(stderr, "event: segment [%d] and [%d] intersect at (%d,%d)\n", (int)e->s1->nr, (int)e->s2->nr, e->p.x, e->p.y);
     } else {
         assert(0);
     }
 }
 
-static inline max32(int32_t v1, int32_t v2) {return v1>v2?v1:v2;}
-static inline min32(int32_t v1, int32_t v2) {return v1<v2?v1:v2;}
+static inline int32_t max32(int32_t v1, int32_t v2) {return v1>v2?v1:v2;}
+static inline int32_t min32(int32_t v1, int32_t v2) {return v1<v2?v1:v2;}
 
 static void segment_dump(segment_t*s)
 {
-    fprintf(stderr, "[%d] (%d,%d)->(%d,%d) ", s->nr, s->a.x, s->a.y, s->b.x, s->b.y);
-    fprintf(stderr, " dx:%d dy:%d k:%f dx/dy=%f\n", s->delta.x, s->delta.y, s->k,
-            (double)s->delta.x / s->delta.y);
+    fprintf(stderr, "[%d] (%d,%d)->(%d,%d) ", (int)s->nr, s->a.x, s->a.y, s->b.x, s->b.y);
+    fprintf(stderr, " dx:%d dy:%d k:%f dx/dy=%f fs=%p\n", s->delta.x, s->delta.y, s->k,
+            (double)s->delta.x / s->delta.y, s->fs);
 }
 
 static void segment_init(segment_t*s, int32_t x1, int32_t y1, int32_t x2, int32_t y2, int polygon_nr, segment_dir_t dir)
@@ -255,10 +291,10 @@ static void segment_init(segment_t*s, int32_t x1, int32_t y1, int32_t x2, int32_
     if(y1!=y2) {
        assert(y1<y2);
     } else {
-        /* up/down for horizontal segments is handled by "rotating"
+        /* We need to make sure horizontal segments always go from left to right.
+          "up/down" for horizontal segments is handled by "rotating"
            them 90° anticlockwise in screen coordinates (tilt your head to
-           the right) 
-           TODO: is this still needed?
+           the right).
         */
         s->dir = DIR_UP;
         if(x1>x2) {
@@ -284,6 +320,11 @@ static void segment_init(segment_t*s, int32_t x1, int32_t y1, int32_t x2, int32_
     s->nr = segment_count++;
 
 #ifdef CHECKS
+    /* notice: on some systems (with some compilers), for the line 
+       (1073741823,-1073741824)->(1073741823,1073741823)
+       we get LINE_EQ(s->a, s) == 1. 
+       That's why we now clamp to 26 bit.
+    */
     assert(LINE_EQ(s->a, s) == 0);
     assert(LINE_EQ(s->b, s) == 0);
 
@@ -301,8 +342,9 @@ static void segment_init(segment_t*s, int32_t x1, int32_t y1, int32_t x2, int32_
     assert(LINE_EQ(p, s) >= 0);
 #endif
 
-    /* TODO: make this int_type */
+#ifndef DONT_REMEMBER_CROSSINGS
     dict_init2(&s->scheduled_crossings, &ptr_type, 0);
+#endif
 }
 
 static segment_t* segment_new(point_t a, point_t b, int polygon_nr, segment_dir_t dir)
@@ -314,7 +356,9 @@ static segment_t* segment_new(point_t a, point_t b, int polygon_nr, segment_dir_
 
 static void segment_clear(segment_t*s)
 {
+#ifndef DONT_REMEMBER_CROSSINGS
     dict_clear(&s->scheduled_crossings);
+#endif
 }
 static void segment_destroy(segment_t*s)
 {
@@ -322,33 +366,47 @@ static void segment_destroy(segment_t*s)
     free(s);
 }
 
-static void advance_stroke(heap_t*queue, gfxpolystroke_t*stroke, int polygon_nr, int pos)
+static void advance_stroke(queue_t*queue, hqueue_t*hqueue, gfxpolystroke_t*stroke, int polygon_nr, int pos)
 {
+    if(!stroke) 
+       return;
+    segment_t*s = 0;
+    /* we need to queue multiple segments at once because we need to process start events
+       before horizontal events */
     while(pos < stroke->num_points-1) {
        assert(stroke->points[pos].y <= stroke->points[pos+1].y);
-       segment_t*s = segment_new(stroke->points[pos], stroke->points[pos+1], polygon_nr, stroke->dir);
-       s->stroke = stroke;
-       s->stroke_pos = ++pos;
+       s = segment_new(stroke->points[pos], stroke->points[pos+1], polygon_nr, stroke->dir);
+       s->fs = stroke->fs;
+       pos++;
+       s->stroke = 0;
+       s->stroke_pos = 0;
 #ifdef DEBUG
        /*if(l->tmp)
            s->nr = l->tmp;*/
-       fprintf(stderr, "[%d] (%d,%d) -> (%d,%d) %s (%d more to come)\n",
+       fprintf(stderr, "[%d] (%d,%d) -> (%d,%d) %s (stroke %p, %d more to come)\n",
                s->nr, s->a.x, s->a.y, s->b.x, s->b.y,
-               s->dir==DIR_UP?"up":"down", stroke->num_points - 1 - pos);
-#endif
-       event_t e = event_new();
-       e.type = s->delta.y ? EVENT_START : EVENT_HORIZONTAL;
-       e.p = s->a;
-       e.s1 = s;
-       e.s2 = 0;
-       heap_put(queue, &e);
-       if(e.type != EVENT_HORIZONTAL) {
+               s->dir==DIR_UP?"up":"down", stroke, stroke->num_points - 1 - pos);
+#endif
+       event_t* e = event_new();
+       e->type = s->delta.y ? EVENT_START : EVENT_HORIZONTAL;
+       e->p = s->a;
+       e->s1 = s;
+       e->s2 = 0;
+       
+       if(queue) queue_put(queue, e);
+       else hqueue_put(hqueue, e);
+
+       if(e->type != EVENT_HORIZONTAL) {
            break;
        }
     }
+    if(s) {
+       s->stroke = stroke;
+       s->stroke_pos = pos;
+    }
 }
 
-static void gfxpoly_enqueue(gfxpoly_t*p, heap_t*queue, int polygon_nr)
+static void gfxpoly_enqueue(gfxpoly_t*p, queue_t*queue, hqueue_t*hqueue, int polygon_nr)
 {
     int t;
     gfxpolystroke_t*stroke = p->strokes;
@@ -361,7 +419,7 @@ static void gfxpoly_enqueue(gfxpoly_t*p, heap_t*queue, int polygon_nr)
            assert(stroke->points[s].y <= stroke->points[s+1].y);
        }
 #endif
-       advance_stroke(queue, stroke, polygon_nr, 0);
+       advance_stroke(queue, hqueue, stroke, polygon_nr, 0);
     }
 }
 
@@ -369,12 +427,12 @@ static void schedule_endpoint(status_t*status, segment_t*s)
 {
     // schedule end point of segment
     assert(s->b.y > status->y);
-    event_t e;
-    e.type = EVENT_END;
-    e.p = s->b;
-    e.s1 = s;
-    e.s2 = 0;
-    heap_put(status->queue, &e);
+    event_t*e = event_new();
+    e->type = EVENT_END;
+    e->p = s->b;
+    e->s1 = s;
+    e->s2 = 0;
+    queue_put(&status->queue, e);
 }
 
 static void schedule_crossing(status_t*status, segment_t*s1, segment_t*s2)
@@ -413,8 +471,7 @@ static void schedule_crossing(status_t*status, segment_t*s1, segment_t*s2)
         return;
     }
 
-#define REMEMBER_CROSSINGS
-#ifdef REMEMBER_CROSSINGS
+#ifndef DONT_REMEMBER_CROSSINGS
     if(dict_contains(&s1->scheduled_crossings, (void*)(ptroff_t)s2->nr)) {
         /* FIXME: this whole segment hashing thing is really slow */
 #ifdef DEBUG
@@ -443,23 +500,8 @@ static void schedule_crossing(status_t*status, segment_t*s1, segment_t*s2)
             return;
         }
     }
+
     double asign2 = LINE_EQ(s1->a, s2);
-    double bsign2 = LINE_EQ(s1->b, s2);
-    if(asign2<0 && bsign2<0) {
-        // segment1 is completely to the left of segment2
-#ifdef DEBUG
-            fprintf(stderr, "[%d] doesn't intersect with [%d] because: [%d] is completely to the left of [%d]\n", s1->nr, s2->nr, s1->nr, s2->nr);
-#endif
-        return;
-    }
-    if(asign2>0 && bsign2>0)  {
-       // TODO: can this ever happen?
-#ifdef DEBUG
-            fprintf(stderr, "[%d] doesn't intersect with [%d] because: [%d] is completely to the left of [%d]\n", s1->nr, s2->nr, s2->nr, s1->nr);
-#endif
-        // segment2 is completely to the left of segment1
-        return;
-    }
     if(asign2==0) {
         // segment1 touches segment2 in a single point (ignored)
 #ifdef DEBUG
@@ -467,6 +509,7 @@ static void schedule_crossing(status_t*status, segment_t*s1, segment_t*s2)
 #endif
         return;
     }
+    double bsign2 = LINE_EQ(s1->b, s2);
     if(bsign2==0) {
         // segment1 touches segment2 in a single point (ignored)
 #ifdef DEBUG
@@ -474,22 +517,26 @@ static void schedule_crossing(status_t*status, segment_t*s1, segment_t*s2)
 #endif
         return;
     }
-    double asign1 = LINE_EQ(s2->a, s1);
-    double bsign1 = LINE_EQ(s2->b, s1);
-    if(asign1<0 && bsign1<0) {
+
+    if(asign2<0 && bsign2<0) {
         // segment1 is completely to the left of segment2
 #ifdef DEBUG
             fprintf(stderr, "[%d] doesn't intersect with [%d] because: [%d] is completely to the left of [%d]\n", s1->nr, s2->nr, s1->nr, s2->nr);
 #endif
         return;
     }
-    if(asign1>0 && bsign1>0)  {
-        // segment2 is completely to the left of segment1
+    if(asign2>0 && bsign2>0)  {
+        // segment1 is completely to the right of segment2
+#ifndef DONT_REMEMBER_CROSSINGS
+       assert(0);
+#endif
 #ifdef DEBUG
             fprintf(stderr, "[%d] doesn't intersect with [%d] because: [%d] is completely to the left of [%d]\n", s1->nr, s2->nr, s2->nr, s1->nr);
 #endif
         return;
     }
+    
+    double asign1 = LINE_EQ(s2->a, s1);
     if(asign1==0) {
         // segment2 touches segment1 in a single point (ignored)
 #ifdef DEBUG
@@ -497,6 +544,7 @@ static void schedule_crossing(status_t*status, segment_t*s1, segment_t*s2)
 #endif
         return;
     }
+    double bsign1 = LINE_EQ(s2->b, s1);
     if(asign2==0) {
         // segment2 touches segment1 in a single point (ignored)
 #ifdef DEBUG
@@ -505,6 +553,34 @@ static void schedule_crossing(status_t*status, segment_t*s1, segment_t*s2)
         return;
     }
 
+    if(asign1<0 && bsign1<0) {
+        // segment2 is completely to the left of segment1
+#ifndef DONT_REMEMBER_CROSSINGS
+       assert(0);
+#endif
+#ifdef DEBUG
+            fprintf(stderr, "[%d] doesn't intersect with [%d] because: [%d] is completely to the left of [%d]\n", s1->nr, s2->nr, s1->nr, s2->nr);
+#endif
+        return;
+    }
+    if(asign1>0 && bsign1>0)  {
+        // segment2 is completely to the right of segment1
+#ifdef DEBUG
+            fprintf(stderr, "[%d] doesn't intersect with [%d] because: [%d] is completely to the left of [%d]\n", s1->nr, s2->nr, s2->nr, s1->nr);
+#endif
+        return;
+    }
+
+#ifdef DONT_REMEMBER_CROSSINGS
+    /* s2 crosses s1 from *left* to *right*. This is a crossing we already processed- 
+       there's not way s2 would be to the left of s1 otherwise */
+    if(asign1<0 && bsign1>0) return;
+    if(asign2>0 && bsign2<0) return;
+#endif
+
+    assert(!(asign1<0 && bsign1>0));
+    assert(!(asign2>0 && bsign2<0));
+
     /* TODO: should we precompute these? */
     double la = (double)s1->a.x*(double)s1->b.y - (double)s1->a.y*(double)s1->b.x;
     double lb = (double)s2->a.x*(double)s2->b.y - (double)s2->a.y*(double)s2->b.x;
@@ -513,10 +589,6 @@ static void schedule_crossing(status_t*status, segment_t*s1, segment_t*s2)
     p.x = (int32_t)ceil((-la*s2->delta.x + lb*s1->delta.x) / det);
     p.y = (int32_t)ceil((+lb*s1->delta.y - la*s2->delta.y) / det);
 
-#ifndef REMEMBER_CROSSINGS
-    if(p.y < status->y) return;
-#endif
-
     assert(p.y >= status->y);
 #ifdef CHECKS
     assert(p.x >= s1->minx && p.x <= s1->maxx);
@@ -525,7 +597,7 @@ static void schedule_crossing(status_t*status, segment_t*s1, segment_t*s2)
     point_t pair;
     pair.x = s1->nr;
     pair.y = s2->nr;
-#ifdef REMEMBER_CROSSINGS
+#ifndef DONT_REMEMBER_CROSSINGS
     assert(!dict_contains(status->seen_crossings, &pair));
     dict_put(status->seen_crossings, &pair, 0);
 #endif
@@ -534,19 +606,19 @@ static void schedule_crossing(status_t*status, segment_t*s1, segment_t*s2)
     fprintf(stderr, "schedule crossing between [%d] and [%d] at (%d,%d)\n", s1->nr, s2->nr, p.x, p.y);
 #endif
 
-#ifdef REMEMBER_CROSSINGS
+#ifndef DONT_REMEMBER_CROSSINGS
     /* we insert into each other's intersection history because these segments might switch
        places and we still want to look them up quickly after they did */
     dict_put(&s1->scheduled_crossings, (void*)(ptroff_t)(s2->nr), 0);
     dict_put(&s2->scheduled_crossings, (void*)(ptroff_t)(s1->nr), 0);
 #endif
 
-    event_t e = event_new();
-    e.type = EVENT_CROSS;
-    e.p = p;
-    e.s1 = s1;
-    e.s2 = s2;
-    heap_put(status->queue, &e);
+    event_t* e = event_new();
+    e->type = EVENT_CROSS;
+    e->p = p;
+    e->s1 = s1;
+    e->s2 = s2;
+    queue_put(&status->queue, e);
     return;
 }
 
@@ -602,13 +674,40 @@ static void insert_point_into_segment(status_t*status, segment_t*s, point_t p)
         fprintf(stderr, "[%d] receives next point (%d,%d)->(%d,%d) (drawing)\n", s->nr,
                 s->pos.x, s->pos.y, p.x, p.y);
 #endif
+       edgestyle_t*fs = s->fs_out;
+       segment_dir_t dir = s->wind.is_filled?DIR_DOWN:DIR_UP;
+
         // omit horizontal lines
         if(s->pos.y != p.y) {
             point_t a = s->pos;
             point_t b = p;
             assert(a.y != b.y);
-           status->writer.moveto(&status->writer, a.x, a.y);
-           status->writer.lineto(&status->writer, b.x, b.y);
+
+            gfxpolystroke_t*stroke = status->strokes;
+           /* find a stoke to attach this segment to. It has to have an endpoint
+              matching our start point, and a matching edgestyle */
+           while(stroke) {
+               point_t p = stroke->points[stroke->num_points-1];
+               if(p.x == a.x && p.y == a.y && stroke->fs == fs && stroke->dir == dir)
+                   break;
+               stroke = stroke->next;
+           }
+           if(!stroke) {
+               stroke = rfx_calloc(sizeof(gfxpolystroke_t));
+               stroke->dir = dir;
+               stroke->fs = fs;
+               stroke->next = status->strokes;
+               status->strokes = stroke;
+               stroke->points_size = 2;
+               stroke->points = rfx_calloc(sizeof(point_t)*stroke->points_size);
+               stroke->points[0] = a;
+               stroke->num_points = 1;
+           } else if(stroke->num_points == stroke->points_size) {
+               assert(stroke->fs);
+               stroke->points_size *= 2;
+               stroke->points = rfx_realloc(stroke->points, sizeof(point_t)*stroke->points_size);
+           }
+           stroke->points[stroke->num_points++] = b;
         }
     } else {
 #ifdef DEBUG
@@ -832,7 +931,7 @@ static void recalculate_windings(status_t*status, segrange_t*range)
     s = range->segmin;
 #endif
 #ifdef CHECKS
-    /* test sanity: check that we don't have changed segments
+    /* test sanity: verify that we don't have changed segments
        outside of the given range */
     s = actlist_leftmost(status->actlist);
     while(s && s!=range->segmin) {
@@ -845,7 +944,7 @@ static void recalculate_windings(status_t*status, segrange_t*range)
         s = s->left;
     }
     /* in check mode, go through the whole interval so we can test
-       that all polygons where the fillstyle changed also have seg->changed=1 */
+       that all polygons where the edgestyle changed also have seg->changed=1 */
     s = actlist_leftmost(status->actlist);
     end = 0;
 #endif
@@ -860,11 +959,12 @@ static void recalculate_windings(status_t*status, segrange_t*range)
             segment_t* left = actlist_left(status->actlist, s);
             windstate_t wind = left?left->wind:status->windrule->start(status->context);
             s->wind = status->windrule->add(status->context, wind, s->fs, s->dir, s->polygon_nr);
-            fillstyle_t*fs_old = s->fs_out;
+            edgestyle_t*fs_old = s->fs_out;
             s->fs_out = status->windrule->diff(&wind, &s->wind);
 
 #ifdef DEBUG
-            fprintf(stderr, "[%d] %s/%d/%s/%s %s\n", s->nr, s->dir==DIR_UP?"up":"down", s->wind.wind_nr, s->wind.is_filled?"fill":"nofill", s->fs_out?"draw":"omit",
+            fprintf(stderr, "[%d] dir=%s wind=%d wind.filled=%s fs_old/new=%s/%s %s\n", s->nr, s->dir==DIR_UP?"up":"down", s->wind.wind_nr, s->wind.is_filled?"fill":"nofill", 
+                   fs_old?"draw":"omit", s->fs_out?"draw":"omit",
                    fs_old!=s->fs_out?"CHANGED":"");
 #endif
             assert(!(!s->changed && fs_old!=s->fs_out));
@@ -927,7 +1027,7 @@ static void event_apply(status_t*status, event_t*e)
             event_dump(e);
 #endif
             intersect_with_horizontal(status, s);
-           advance_stroke(status->queue, s->stroke, s->polygon_nr, s->stroke_pos);
+           advance_stroke(&status->queue, 0, s->stroke, s->polygon_nr, s->stroke_pos);
             segment_destroy(s);e->s1=0;
             break;
         }
@@ -952,7 +1052,7 @@ static void event_apply(status_t*status, event_t*e)
            /* schedule segment for xrow handling */
             s->left = 0; s->right = status->ending_segments;
             status->ending_segments = s;
-           advance_stroke(status->queue, s->stroke, s->polygon_nr, s->stroke_pos);
+           advance_stroke(&status->queue, 0, s->stroke, s->polygon_nr, s->stroke_pos);
             break;
         }
         case EVENT_START: {
@@ -985,7 +1085,7 @@ static void event_apply(status_t*status, event_t*e)
 #ifdef DEBUG
                fprintf(stderr, "Ignore this crossing ([%d] not next to [%d])\n", e->s1->nr, e->s2->nr);
 #endif
-#ifdef REMEMBER_CROSSINGS
+#ifndef DONT_REMEMBER_CROSSINGS
                 /* ignore this crossing for now (there are some line segments in between).
                    it'll get rescheduled as soon as the "obstacles" are gone */
                 char del1 = dict_del(&e->s1->scheduled_crossings, (void*)(ptroff_t)e->s2->nr);
@@ -996,7 +1096,7 @@ static void event_apply(status_t*status, event_t*e)
                 point_t pair;
                 pair.x = e->s1->nr;
                 pair.y = e->s2->nr;
-#ifdef REMEMBER_CROSSINGS
+#ifndef DONT_REMEMBER_CROSSINGS
                 assert(dict_contains(status->seen_crossings, &pair));
                 dict_del(status->seen_crossings, &pair);
 #endif
@@ -1014,7 +1114,7 @@ static void check_status(status_t*status)
             s->pos.y != s->b.y) &&
            !dict_contains(status->segs_with_point, s)) {
             fprintf(stderr, "Error: segment [%d] (%sslope) intersects in scanline %d, but it didn't receive a point\n",
-                    s->nr,
+                    SEGNR(s),
                     s->delta.x<0?"-":"+",
                     status->y);
             assert(0);
@@ -1036,25 +1136,32 @@ static void add_horizontals(gfxpoly_t*poly, windrule_t*windrule, windcontext_t*c
 #ifdef DEBUG
     fprintf(stderr, "========================================================================\n");
 #endif
-    heap_t* queue = heap_new(sizeof(event_t), compare_events_simple);
-    gfxpoly_enqueue(poly, queue, 0);
+    hqueue_t hqueue;
+    hqueue_init(&hqueue);
+    gfxpoly_enqueue(poly, 0, &hqueue, 0);
 
     actlist_t* actlist = actlist_new();
-
-    event_t*e = heap_chopmax(queue);
+       
+    event_t*e = hqueue_get(&hqueue);
     while(e) {
         int32_t y = e->p.y;
         int32_t x = 0;
-        char fill = 0;
 #ifdef DEBUG
-        fprintf(stderr, "----------------------------------- %d\n", y);
+        fprintf(stderr, "HORIZONTALS ----------------------------------- %d\n", y);
         actlist_dump(actlist, y-1);
 #endif
 #ifdef CHECKS
         actlist_verify(actlist, y-1);
 #endif
+       edgestyle_t*fill = 0;
+       char dir_up = 0;
+       char dir_down = 0;
+
         do {
+           assert(e->s1->fs);
             if(fill && x != e->p.x) {
+               assert(!dir_up || !dir_down);
+               assert(dir_up || dir_down);
 #ifdef DEBUG
                 fprintf(stderr, "%d) draw horizontal line from %d to %d\n", y, x, e->p.x);
 #endif
@@ -1066,8 +1173,8 @@ static void add_horizontals(gfxpoly_t*poly, windrule_t*windrule, windcontext_t*c
 
                stroke->num_points = 2;
                stroke->points = malloc(sizeof(point_t)*2);
-               stroke->dir = DIR_UP; // FIXME
-               stroke->fs = 0;
+               stroke->dir = dir_up?DIR_UP:DIR_DOWN;
+               stroke->fs = fill;
                point_t a,b;
                 a.y = b.y = y;
                /* we draw from low x to high x so that left/right fillstyles add up
@@ -1079,7 +1186,7 @@ static void add_horizontals(gfxpoly_t*poly, windrule_t*windrule, windcontext_t*c
                stroke->points[1] = b;
 #ifdef CHECKS
                /* the output should always be intersection free polygons, so check this horizontal
-                  line isn't hacking through any segments in the active list */
+                  line isn't puncturing any segments in the active list */
                segment_t* start = actlist_find(actlist, b, b);
                segment_t* s = actlist_find(actlist, a, a);
                while(s!=start) {
@@ -1088,33 +1195,65 @@ static void add_horizontals(gfxpoly_t*poly, windrule_t*windrule, windcontext_t*c
                }
 #endif
             }
-            segment_t*left = 0;
-            segment_t*s = e->s1;
 
+           segment_t*s = e->s1;
+
+            segment_t*left = 0;
             switch(e->type) {
                 case EVENT_START: {
                    assert(e->p.x == s->a.x && e->p.y == s->a.y);
                     actlist_insert(actlist, s->a, s->b, s);
-                    event_t e;
-                    e.type = EVENT_END;
-                    e.p = s->b;
-                    e.s1 = s;
-                    e.s2 = 0;
-                    heap_put(queue, &e);
+                    event_t* e = event_new();
+                    e->type = EVENT_END;
+                    e->p = s->b;
+                    e->s1 = s;
+                    e->s2 = 0;
+                    hqueue_put(&hqueue, e);
                     left = actlist_left(actlist, s);
+                   if(e->s1->dir==DIR_UP)
+                       dir_up^=1;
+                   else
+                       dir_down^=1;
                     break;
                 }
                 case EVENT_END: {
                     left = actlist_left(actlist, s);
                     actlist_delete(actlist, s);
-                   advance_stroke(queue, s->stroke, s->polygon_nr, s->stroke_pos);
+                   advance_stroke(0, &hqueue, s->stroke, s->polygon_nr, s->stroke_pos);
+                   if(e->s1->dir==DIR_DOWN)
+                       dir_up^=1;
+                   else
+                       dir_down^=1;
                     break;
                 }
                 default: assert(0);
             }
 
             x = e->p.x;
-            fill ^= 1;//(before.is_filled != after.is_filled);
+               
+           fill = fill?0:&edgestyle_default;
+#if 0
+           if(windrule==&windrule_evenodd) {
+               if(!!fill != !!fill2) {
+                   segment_dump(s);
+                   event_dump(e);
+                   printf("at y=%d x=%d (hline:%p)\n", e->p.y, x, old_fill);
+                   if(e->type==EVENT_END) {
+                       printf("            %9p\n", s->fs);
+                       printf("               |\n");
+                   }
+                   printf("              %3d %c%2d \n", before1.is_filled, e->type==EVENT_END?'|':' ', after1.is_filled);
+                   printf("%12p -----+----- %p\n", old_fill, fill2);
+                   printf("              %3d %c%2d \n", before2.is_filled, e->type==EVENT_START?'|':' ', after2.is_filled);
+                   if(e->type==EVENT_START) {
+                       printf("                  |\n");
+                       printf("             %9p\n", s->fs);
+                   }
+               }
+               assert(!!fill == !!fill2);
+           }
+#endif
+
 #ifdef DEBUG
             fprintf(stderr, "%d) event=%s[%d] left:[%d] x:%d\n",
                     y, e->type==EVENT_START?"start":"end",
@@ -1126,45 +1265,51 @@ static void add_horizontals(gfxpoly_t*poly, windrule_t*windrule, windcontext_t*c
             if(e->type == EVENT_END)
                 segment_destroy(s);
 
-            free(e);
-            e = heap_chopmax(queue);
+           event_free(e);
+            e = hqueue_get(&hqueue);
         } while(e && y == e->p.y);
 
-        assert(!fill); // check that polygon is not bleeding
+#ifdef CHECKS
+       edgestyle_t*bleeding = fill;
+        assert(!bleeding);
+#endif
     }
 
     actlist_destroy(actlist);
-    heap_destroy(queue);
+    hqueue_destroy(&hqueue);
 }
 
-gfxpoly_t* gfxpoly_process(gfxpoly_t*poly, windrule_t*windrule, windcontext_t*context)
+gfxpoly_t* gfxpoly_process(gfxpoly_t*poly1, gfxpoly_t*poly2, windrule_t*windrule, windcontext_t*context)
 {
-    current_polygon = poly;
-    heap_t* queue = heap_new(sizeof(event_t), compare_events);
-
-    gfxpoly_enqueue(poly, queue, /*polygon nr*/0);
+    current_polygon = poly1;
 
     status_t status;
     memset(&status, 0, sizeof(status_t));
-    status.queue = queue;
+    queue_init(&status.queue);
+    gfxpoly_enqueue(poly1, &status.queue, 0, /*polygon nr*/0);
+    if(poly2) {
+       assert(poly1->gridsize == poly2->gridsize);
+       gfxpoly_enqueue(poly2, &status.queue, 0, /*polygon nr*/1);
+    }
+
     status.windrule = windrule;
     status.context = context;
     status.actlist = actlist_new();
-    gfxpolywriter_init(&status.writer);
-    status.writer.setgridsize(&status.writer, poly->gridsize);
 
 #ifdef CHECKS
     status.seen_crossings = dict_new2(&point_type);
-    int lasty=heap_peek(queue)?((event_t*)heap_peek(queue))->p.y-1:0;
+    int32_t lasty=-0x80000000;
 #endif
 
     status.xrow = xrow_new();
 
-    event_t*e = heap_chopmax(queue);
+    event_t*e = queue_get(&status.queue);
     while(e) {
+       assert(e->s1->fs);
         status.y = e->p.y;
-       assert(status.y>=lasty);
 #ifdef CHECKS
+       assert(status.y>=lasty);
+       lasty = status.y;
         status.intersecting_segs = dict_new2(&ptr_type);
         status.segs_with_point = dict_new2(&ptr_type);
 #endif
@@ -1180,8 +1325,8 @@ gfxpoly_t* gfxpoly_process(gfxpoly_t*poly, windrule_t*windrule, windcontext_t*co
         do {
             xrow_add(status.xrow, e->p.x);
             event_apply(&status, e);
-            free(e);
-            e = heap_chopmax(queue);
+           event_free(e);
+            e = queue_get(&status.queue);
         } while(e && status.y == e->p.y);
 
         xrow_sort(status.xrow);
@@ -1205,11 +1350,34 @@ gfxpoly_t* gfxpoly_process(gfxpoly_t*poly, windrule_t*windrule, windcontext_t*co
     dict_destroy(status.seen_crossings);
 #endif
     actlist_destroy(status.actlist);
-    heap_destroy(queue);
+    queue_destroy(&status.queue);
     xrow_destroy(status.xrow);
 
-    gfxpoly_t*p = (gfxpoly_t*)status.writer.finish(&status.writer);
+    gfxpoly_t*p = (gfxpoly_t*)malloc(sizeof(gfxpoly_t));
+    p->gridsize = poly1->gridsize;
+    p->strokes = status.strokes;
+
+#ifdef CHECKS
+    /* we only add segments with non-empty edgestyles to strokes in
+       recalculate_windings, but better safe than sorry */
+    gfxpolystroke_t*stroke = p->strokes;
+    while(stroke) {
+       assert(stroke->fs);
+       stroke = stroke->next;
+    }
+#endif
 
     add_horizontals(p, &windrule_evenodd, context); // output is always even/odd
+    //add_horizontals(p, windrule, context);
     return p;
 }
+
+static windcontext_t twopolygons = {2};
+gfxpoly_t* gfxpoly_intersect(gfxpoly_t*p1, gfxpoly_t*p2)
+{
+    return gfxpoly_process(p1, p2, &windrule_intersect, &twopolygons);
+}
+gfxpoly_t* gfxpoly_union(gfxpoly_t*p1, gfxpoly_t*p2)
+{
+    return gfxpoly_process(p1, p2, &windrule_union, &twopolygons);
+}