actlist_t*actlist;
heap_t*queue;
edge_t*output;
+ xrow_t*xrow;
#ifdef DEBUG
dict_t*seen_crossings; //list of crossing we saw so far
dict_t*intersecting_segs; //list of segments intersecting in this scanline
void event_dump(event_t*e)
{
- if(e->type == EVENT_START) {
+ 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);
+ } 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);
} 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);
void segment_init(segment_t*s, int x1, int y1, int x2, int y2)
{
- assert(y1!=y2);
if(y1<y2) {
s->dir = DIR_DOWN;
- } else {
+ } else if(y1>y2) {
int x = x1;x1=x2;x2=x;
int y = y1;y1=y2;y2=y;
s->dir = DIR_UP;
+ } else {
+ /* up/down for horizontal segments is handled by "rotating"
+ them 90° anticlockwise in screen coordinates (tilt your head to
+ the right) */
+ s->dir = DIR_UP;
+ if(x1>x2) {
+ s->dir = DIR_DOWN;
+ int x = x1;x1=x2;x2=x;
+ int y = y1;y1=y2;y2=y;
+ }
}
s->a.x = x1;
s->a.y = y1;
s->delta.x = x2-x1;
s->delta.y = y2-y1;
s->pos = s->a;
- s->tmp = -1;
-#ifdef DEBUG
- static int segment_count=0; //for debugging
+ s->new_point.y = y1-1;
+#define XDEBUG
+#ifdef XDEBUG
+ static int segment_count=0;
s->nr = segment_count++;
#endif
void gfxpoly_enqueue(edge_t*list, heap_t*queue)
{
- edge_t*l = list;
- while(l) {
+ edge_t*l;
+ for(l=list;l;l=l->next) {
+ if(l->a.x == l->b.x &&
+ l->a.y == l->b.y) {
+ fprintf(stderr, "Warning: intersector input contains zero-length segments\n");
+ continue;
+ }
segment_t*s = segment_new(l->a.x, l->a.y, l->b.x, l->b.y);
#ifdef DEBUG
fprintf(stderr, "[%d] (%d,%d) -> (%d,%d) %s\n",
s->dir==DIR_UP?"up":"down");
#endif
event_t e = event_new();
- e.type = EVENT_START;
+ e.type = s->delta.y ? EVENT_START : EVENT_HORIZONTAL;
e.p = s->a;
e.s1 = s;
e.s2 = 0;
heap_put(queue, &e);
- l = l->next;
}
}
}
if(dict_contains(&s1->scheduled_crossings, s2)) {
+ /* FIXME: this whole segment hashing thing is really slow */
+ //fprintf(stderr, "Encountered crossing between [%d] and [%d] twice\n", s1->nr, s2->nr);
+
// we already know about this one
return;
}
schedule_crossing(status, s1, right);
}
+typedef struct _box {
+ point_t left1, left2, right1, right2;
+} box_t;
+static inline box_t box_new(int x, int y)
+{
+ box_t box;
+ box.right1.x = box.right2.x = x;
+ box.left1.x = box.left2.x = x-1;
+ box.left1.y = box.right1.y = y-1;
+ box.left2.y = box.right2.y = y;
+ return box;
+}
+
void insert_point_into_segment(status_t*status, segment_t*s, point_t p)
{
+ edge_t*e = malloc(sizeof(edge_t));
+ e->a = s->pos;
+ e->b = p;
+ assert(e->a.y != e->b.y);
+ e->next = status->output;
+ status->output = e;
+}
+
+void mark_point_in_segment(status_t*status, segment_t*s, point_t p)
+{
#ifdef DEBUG
if(s->pos.x == p.x && s->pos.y == p.y) {
fprintf(stderr, "Error: tried to add (%d,%d) to segment [%d] twice\n", p.x, p.y, s->nr);
assert(s->pos.x != p.x || s->pos.y != p.y);
#ifdef DEBUG
fprintf(stderr, "[%d] gets extra point (%d,%d)\n", s->nr, p.x, p.y);
+ if(!dict_contains(status->segs_with_point, s))
+ dict_put(status->segs_with_point, s, 0);
#endif
-
- edge_t*e = malloc(sizeof(edge_t));
- e->a = s->pos;
- e->b = p;
- e->next = status->output;
- status->output = e;
-
- s->pos = p;
+ if(s->new_point.y != p.y) {
+ s->new_point = p;
+ }
+ s->new_pos = p;
}
-typedef struct _box {
- point_t left1, left2, right1, right2;
-} box_t;
-static inline box_t box_new(int x, int y)
-{
- box_t box;
- box.right1.x = box.right2.x = x;
- box.left1.x = box.left2.x = x-1;
- box.left1.y = box.right1.y = y-1;
- box.left2.y = box.right2.y = y;
- return box;
-}
-
/* possible optimizations:
1.) keep two different active lists around, one for negative and one for
positive slopes
*/
/*
SLOPE_POSITIVE:
- + \ +
+ \+ \ +
------ I \I
-I\---- I
I \ --I\---
I \ I \ -------
+ \ + \
*/
-void add_points_to_positively_sloped_segments(status_t*status, xrow_t*xrow, int32_t y)
+static void mark_points_in_positively_sloped_segments(status_t*status, int32_t y)
{
int t;
- for(t=0;t<xrow->num;t++) {
- box_t box = box_new(xrow->x[t], y);
+ for(t=0;t<status->xrow->num;t++) {
+ box_t box = box_new(status->xrow->x[t], y);
segment_t*seg = actlist_find(status->actlist, box.left2, box.left2);
- if(seg)
- seg = seg->right;
- else
- seg = actlist_leftmost(status->actlist);
+ seg = actlist_right(status->actlist, seg);
while(seg) {
if(seg->a.y == y) {
// this segment just started, ignore it
double d1 = LINE_EQ(box.right1, seg);
double d2 = LINE_EQ(box.right2, seg);
if(d1>=0 || d2>=0) {
-#ifdef DEBUG
- dict_put(status->segs_with_point, seg, 0);
-#endif
- insert_point_into_segment(status, seg, box.right2);
+ mark_point_in_segment(status, seg, box.right2);
} else {
break;
}
}
- seg = seg->right;
+ seg = actlist_right(status->actlist, seg);
}
}
}
| I | /I /
| /+ |/ + /
*/
-void add_points_to_negatively_sloped_segments(status_t*status, xrow_t*xrow, int32_t y)
+static void mark_points_in_negatively_sloped_segments(status_t*status, int32_t y)
{
int t;
- for(t=xrow->num-1;t>=0;t--) {
- box_t box = box_new(xrow->x[t], y);
+ for(t=status->xrow->num-1;t>=0;t--) {
+ box_t box = box_new(status->xrow->x[t], y);
segment_t*seg = actlist_find(status->actlist, box.right2, box.right2);
while(seg) {
if(seg->a.y == y) {
double d1 = LINE_EQ(box.left1, seg);
double d2 = LINE_EQ(box.left2, seg);
if(d1<0 || d2<0) {
-#ifdef DEBUG
- dict_put(status->segs_with_point, seg, 0);
-#endif
- insert_point_into_segment(status, seg, box.right2);
+ mark_point_in_segment(status, seg, box.right2);
} else {
break;
}
}
- seg = seg->left;
+ seg = actlist_left(status->actlist, seg);
+ }
+ }
+}
+
+static void add_points(status_t*status)
+{
+ /* TODO: we could use some clever second linked list structure so that we
+ only need to process points which we know we marked */
+ int t;
+ segment_t*s = actlist_leftmost(status->actlist);
+ while(s) {
+ if(s->new_point.y == status->y) {
+ insert_point_into_segment(status, s, s->new_point);
+ s->pos = s->new_pos;
}
+ s = actlist_right(status->actlist, s);
+ }
+}
+
+void intersect_with_horizontal(status_t*status, segment_t*h)
+{
+ segment_t* left = actlist_find(status->actlist, h->a, h->a);
+ segment_t* right = actlist_find(status->actlist, h->b, h->b);
+
+ segment_t* s = right;
+
+ while(s!=left) {
+ assert(s);
+ /*
+ x1 + ((x2-x1)*(y-y1)) / dy =
+ (x1*(y2-y) + x2*(y-y1)) / dy
+ */
+ point_t p;
+ p.y = status->y;
+ p.x = XPOS(s, p.y);
+#ifdef DEBUG
+ fprintf(stderr, "...into [%d] (%d,%d) -> (%d,%d) at (%d,%d)\n", s->nr,
+ s->a.x, s->a.y,
+ s->b.x, s->b.y,
+ p.x, p.y
+ );
+#endif
+ assert(p.x >= h->a.x);
+ assert(p.x <= h->b.x);
+ assert(s->delta.x > 0 && p.x >= s->a.x || s->delta.x <= 0 && p.x <= s->a.x);
+ assert(s->delta.x > 0 && p.x <= s->b.x || s->delta.x <= 0 && p.x >= s->b.x);
+ xrow_add(status->xrow, p.x);
+
+ s = actlist_left(status->actlist, s);
}
+ xrow_add(status->xrow, h->a.x);
}
void event_apply(status_t*status, event_t*e)
{
switch(e->type) {
+ case EVENT_HORIZONTAL: {
+#ifdef DEBUG
+ event_dump(e);
+#endif
+ intersect_with_horizontal(status, e->s1);
+ break;
+ }
case EVENT_END: {
//delete segment from list
segment_t*s = e->s1;
gfxpoly_dump(poly);
#endif
- xrow_t*xrow = xrow_new();
+ status.xrow = xrow_new();
event_t*e = heap_chopmax(queue);
while(e) {
fprintf(stderr, "----------------------------------- %d\n", status.y);
actlist_verify_and_dump(status.actlist, status.y-1);
#endif
- xrow_reset(xrow);
+ xrow_reset(status.xrow);
do {
- xrow_add(xrow, e->p.x);
+ if(e->type != EVENT_HORIZONTAL) {
+ xrow_add(status.xrow, e->p.x);
+ }
event_apply(&status, e);
free(e);
e = heap_chopmax(queue);
} while(e && status.y == e->p.y);
- xrow_sort(xrow);
- add_points_to_positively_sloped_segments(&status, xrow, status.y);
- add_points_to_negatively_sloped_segments(&status, xrow, status.y);
+ xrow_sort(status.xrow);
+ mark_points_in_positively_sloped_segments(&status, status.y);
+ mark_points_in_negatively_sloped_segments(&status, status.y);
+ add_points(&status);
#ifdef DEBUG
check_status(&status);
dict_destroy(status.intersecting_segs);
#endif
actlist_destroy(status.actlist);
heap_destroy(queue);
- xrow_destroy(xrow);
+ xrow_destroy(status.xrow);
return status.output;
}
git.asbjorn.biz / swftools.git / blobdiff