mirror of
https://github.com/mozilla/gecko-dev.git
synced 2024-11-05 08:35:26 +00:00
0382578602
2001-11-07 changes to use the new intersector code. These files are licensed under the LGPL. a=brendan@mozilla.org
1705 lines
42 KiB
C
1705 lines
42 KiB
C
/* Libart_LGPL - library of basic graphic primitives
|
|
* Copyright (C) 2001 Raph Levien
|
|
*
|
|
* This library is free software; you can redistribute it and/or
|
|
* modify it under the terms of the GNU Library General Public
|
|
* License as published by the Free Software Foundation; either
|
|
* version 2 of the License, or (at your option) any later version.
|
|
*
|
|
* This library is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
|
* Library General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU Library General Public
|
|
* License along with this library; if not, write to the
|
|
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
|
|
* Boston, MA 02111-1307, USA.
|
|
*/
|
|
|
|
/* This file contains a testbed implementation of the new intersection
|
|
code.
|
|
*/
|
|
|
|
#include <math.h> /* for sqrt */
|
|
|
|
/* Sanitychecking verifies the main invariant on every priority queue
|
|
point. Do not use in production, as it slows things down way too
|
|
much. */
|
|
#define noSANITYCHECK
|
|
|
|
/* This can be used in production, to prevent hangs. Eventually, it
|
|
should not be necessary. */
|
|
#define CHEAP_SANITYCHECK
|
|
|
|
#define noVERBOSE
|
|
|
|
#include "art_misc.h"
|
|
#include "art_svp.h"
|
|
#include "art_svp_intersect.h"
|
|
|
|
/* A priority queue - perhaps move to a separate file if it becomes
|
|
needed somewhere else */
|
|
|
|
#define ART_PRIQ_USE_HEAP
|
|
|
|
typedef struct _ArtPriQ ArtPriQ;
|
|
typedef struct _ArtPriPoint ArtPriPoint;
|
|
|
|
struct _ArtPriQ {
|
|
int n_items;
|
|
int n_items_max;
|
|
ArtPriPoint **items;
|
|
};
|
|
|
|
struct _ArtPriPoint {
|
|
double x;
|
|
double y;
|
|
void *user_data;
|
|
};
|
|
|
|
static ArtPriQ *
|
|
art_pri_new (void)
|
|
{
|
|
ArtPriQ *result = art_new (ArtPriQ, 1);
|
|
|
|
result->n_items = 0;
|
|
result->n_items_max = 16;
|
|
result->items = art_new (ArtPriPoint *, result->n_items_max);
|
|
return result;
|
|
}
|
|
|
|
static void
|
|
art_pri_free (ArtPriQ *pq)
|
|
{
|
|
art_free (pq->items);
|
|
art_free (pq);
|
|
}
|
|
|
|
static art_boolean
|
|
art_pri_empty (ArtPriQ *pq)
|
|
{
|
|
return pq->n_items == 0;
|
|
}
|
|
|
|
#ifdef ART_PRIQ_USE_HEAP
|
|
|
|
/* This heap implementation is based on Vasek Chvatal's course notes:
|
|
http://www.cs.rutgers.edu/~chvatal/notes/pq.html#heap */
|
|
|
|
static void
|
|
art_pri_bubble_up (ArtPriQ *pq, int vacant, ArtPriPoint *missing)
|
|
{
|
|
ArtPriPoint **items = pq->items;
|
|
int parent;
|
|
|
|
parent = (vacant - 1) >> 1;
|
|
while (vacant > 0 && (missing->y < items[parent]->y ||
|
|
(missing->y == items[parent]->y &&
|
|
missing->x < items[parent]->x)))
|
|
{
|
|
items[vacant] = items[parent];
|
|
vacant = parent;
|
|
parent = (vacant - 1) >> 1;
|
|
}
|
|
|
|
items[vacant] = missing;
|
|
}
|
|
|
|
static void
|
|
art_pri_insert (ArtPriQ *pq, ArtPriPoint *point)
|
|
{
|
|
if (pq->n_items == pq->n_items_max)
|
|
art_expand (pq->items, ArtPriPoint *, pq->n_items_max);
|
|
|
|
art_pri_bubble_up (pq, pq->n_items++, point);
|
|
}
|
|
|
|
static void
|
|
art_pri_sift_down_from_root (ArtPriQ *pq, ArtPriPoint *missing)
|
|
{
|
|
ArtPriPoint **items = pq->items;
|
|
int vacant = 0, child = 2;
|
|
int n = pq->n_items;
|
|
|
|
while (child < n)
|
|
{
|
|
if (items[child - 1]->y < items[child]->y ||
|
|
(items[child - 1]->y == items[child]->y &&
|
|
items[child - 1]->x < items[child]->x))
|
|
child--;
|
|
items[vacant] = items[child];
|
|
vacant = child;
|
|
child = (vacant + 1) << 1;
|
|
}
|
|
if (child == n)
|
|
{
|
|
items[vacant] = items[n - 1];
|
|
vacant = n - 1;
|
|
}
|
|
|
|
art_pri_bubble_up (pq, vacant, missing);
|
|
}
|
|
|
|
static ArtPriPoint *
|
|
art_pri_choose (ArtPriQ *pq)
|
|
{
|
|
ArtPriPoint *result = pq->items[0];
|
|
|
|
art_pri_sift_down_from_root (pq, pq->items[--pq->n_items]);
|
|
return result;
|
|
}
|
|
|
|
#else
|
|
|
|
/* Choose least point in queue */
|
|
static ArtPriPoint *
|
|
art_pri_choose (ArtPriQ *pq)
|
|
{
|
|
int i;
|
|
int best = 0;
|
|
double best_x, best_y;
|
|
double y;
|
|
ArtPriPoint *result;
|
|
|
|
if (pq->n_items == 0)
|
|
return NULL;
|
|
|
|
best_x = pq->items[best]->x;
|
|
best_y = pq->items[best]->y;
|
|
|
|
for (i = 1; i < pq->n_items; i++)
|
|
{
|
|
y = pq->items[i]->y;
|
|
if (y < best_y || (y == best_y && pq->items[i]->x < best_x))
|
|
{
|
|
best = i;
|
|
best_x = pq->items[best]->x;
|
|
best_y = y;
|
|
}
|
|
}
|
|
result = pq->items[best];
|
|
pq->items[best] = pq->items[--pq->n_items];
|
|
return result;
|
|
}
|
|
|
|
static void
|
|
art_pri_insert (ArtPriQ *pq, ArtPriPoint *point)
|
|
{
|
|
if (pq->n_items == pq->n_items_max)
|
|
art_expand (pq->items, ArtPriPoint *, pq->n_items_max);
|
|
|
|
pq->items[pq->n_items++] = point;
|
|
}
|
|
|
|
#endif
|
|
|
|
#ifdef TEST_PRIQ
|
|
|
|
#include <stdlib.h> /* for rand() */
|
|
#include <stdio.h>
|
|
|
|
static double
|
|
double_rand (double lo, double hi, int quant)
|
|
{
|
|
int tmp = rand () / (RAND_MAX * (1.0 / quant)) + 0.5;
|
|
return lo + tmp * ((hi - lo) / quant);
|
|
}
|
|
|
|
/*
|
|
* This custom allocator for priority queue points is here so I can
|
|
* test speed. It doesn't look like it will be that significant, but
|
|
* if I want a small improvement later, it's something.
|
|
*/
|
|
|
|
typedef ArtPriPoint *ArtPriPtPool;
|
|
|
|
static ArtPriPtPool *
|
|
art_pri_pt_pool_new (void)
|
|
{
|
|
ArtPriPtPool *result = art_new (ArtPriPtPool, 1);
|
|
*result = NULL;
|
|
return result;
|
|
}
|
|
|
|
static ArtPriPoint *
|
|
art_pri_pt_alloc (ArtPriPtPool *pool)
|
|
{
|
|
ArtPriPoint *result = *pool;
|
|
if (result == NULL)
|
|
return art_new (ArtPriPoint, 1);
|
|
else
|
|
{
|
|
*pool = result->user_data;
|
|
return result;
|
|
}
|
|
}
|
|
|
|
static void
|
|
art_pri_pt_free (ArtPriPtPool *pool, ArtPriPoint *pt)
|
|
{
|
|
pt->user_data = *pool;
|
|
*pool = pt;
|
|
}
|
|
|
|
static void
|
|
art_pri_pt_pool_free (ArtPriPtPool *pool)
|
|
{
|
|
ArtPriPoint *pt = *pool;
|
|
while (pt != NULL)
|
|
{
|
|
ArtPriPoint *next = pt->user_data;
|
|
art_free (pt);
|
|
pt = next;
|
|
}
|
|
art_free (pool);
|
|
}
|
|
|
|
int
|
|
main (int argc, char **argv)
|
|
{
|
|
ArtPriPtPool *pool = art_pri_pt_pool_new ();
|
|
ArtPriQ *pq;
|
|
int i, j;
|
|
const int n_iter = 1;
|
|
const int pq_size = 100;
|
|
|
|
for (j = 0; j < n_iter; j++)
|
|
{
|
|
pq = art_pri_new ();
|
|
|
|
for (i = 0; i < pq_size; i++)
|
|
{
|
|
ArtPriPoint *pt = art_pri_pt_alloc (pool);
|
|
pt->x = double_rand (0, 1, 100);
|
|
pt->y = double_rand (0, 1, 100);
|
|
pt->user_data = (void *)i;
|
|
art_pri_insert (pq, pt);
|
|
}
|
|
|
|
while (!art_pri_empty (pq))
|
|
{
|
|
ArtPriPoint *pt = art_pri_choose (pq);
|
|
if (n_iter == 1)
|
|
printf ("(%g, %g), %d\n", pt->x, pt->y, (int)pt->user_data);
|
|
art_pri_pt_free (pool, pt);
|
|
}
|
|
|
|
art_pri_free (pq);
|
|
}
|
|
art_pri_pt_pool_free (pool);
|
|
return 0;
|
|
}
|
|
|
|
#else /* TEST_PRIQ */
|
|
|
|
/* A virtual class for an "svp writer". A client of this object creates an
|
|
SVP by repeatedly calling "add segment" and "add point" methods on it.
|
|
*/
|
|
|
|
typedef struct _ArtSvpWriterRewind ArtSvpWriterRewind;
|
|
|
|
/* An implementation of the svp writer virtual class that applies the
|
|
winding rule. */
|
|
|
|
struct _ArtSvpWriterRewind {
|
|
ArtSvpWriter super;
|
|
ArtWindRule rule;
|
|
ArtSVP *svp;
|
|
int n_segs_max;
|
|
int *n_points_max;
|
|
};
|
|
|
|
static int
|
|
art_svp_writer_rewind_add_segment (ArtSvpWriter *self, int wind_left,
|
|
int delta_wind, double x, double y)
|
|
{
|
|
ArtSvpWriterRewind *swr = (ArtSvpWriterRewind *)self;
|
|
ArtSVP *svp;
|
|
ArtSVPSeg *seg;
|
|
art_boolean left_filled, right_filled;
|
|
int wind_right = wind_left + delta_wind;
|
|
int seg_num;
|
|
const int init_n_points_max = 4;
|
|
|
|
switch (swr->rule)
|
|
{
|
|
case ART_WIND_RULE_NONZERO:
|
|
left_filled = (wind_left != 0);
|
|
right_filled = (wind_right != 0);
|
|
break;
|
|
case ART_WIND_RULE_INTERSECT:
|
|
left_filled = (wind_left > 1);
|
|
right_filled = (wind_right > 1);
|
|
break;
|
|
case ART_WIND_RULE_ODDEVEN:
|
|
left_filled = (wind_left & 1);
|
|
right_filled = (wind_right & 1);
|
|
break;
|
|
case ART_WIND_RULE_POSITIVE:
|
|
left_filled = (wind_left > 0);
|
|
right_filled = (wind_right > 0);
|
|
break;
|
|
default:
|
|
art_die ("Unknown wind rule %d\n", swr->rule);
|
|
}
|
|
if (left_filled == right_filled)
|
|
{
|
|
/* discard segment now */
|
|
#ifdef VERBOSE
|
|
art_dprint ("swr add_segment: %d += %d (%g, %g) --> -1\n",
|
|
wind_left, delta_wind, x, y);
|
|
#endif
|
|
return -1;
|
|
}
|
|
|
|
svp = swr->svp;
|
|
seg_num = svp->n_segs++;
|
|
if (swr->n_segs_max == seg_num)
|
|
{
|
|
swr->n_segs_max <<= 1;
|
|
svp = (ArtSVP *)art_realloc (svp, sizeof(ArtSVP) +
|
|
(swr->n_segs_max - 1) *
|
|
sizeof(ArtSVPSeg));
|
|
swr->svp = svp;
|
|
swr->n_points_max = art_renew (swr->n_points_max, int,
|
|
swr->n_segs_max);
|
|
}
|
|
seg = &svp->segs[seg_num];
|
|
seg->n_points = 1;
|
|
seg->dir = right_filled;
|
|
swr->n_points_max[seg_num] = init_n_points_max;
|
|
seg->bbox.x0 = x;
|
|
seg->bbox.y0 = y;
|
|
seg->bbox.x1 = x;
|
|
seg->bbox.y1 = y;
|
|
seg->points = art_new (ArtPoint, init_n_points_max);
|
|
seg->points[0].x = x;
|
|
seg->points[0].y = y;
|
|
#ifdef VERBOSE
|
|
art_dprint ("swr add_segment: %d += %d (%g, %g) --> %d(%s)\n",
|
|
wind_left, delta_wind, x, y, seg_num,
|
|
seg->dir ? "v" : "^");
|
|
#endif
|
|
return seg_num;
|
|
}
|
|
|
|
static void
|
|
art_svp_writer_rewind_add_point (ArtSvpWriter *self, int seg_id,
|
|
double x, double y)
|
|
{
|
|
ArtSvpWriterRewind *swr = (ArtSvpWriterRewind *)self;
|
|
ArtSVPSeg *seg;
|
|
int n_points;
|
|
|
|
#ifdef VERBOSE
|
|
art_dprint ("swr add_point: %d (%g, %g)\n", seg_id, x, y);
|
|
#endif
|
|
if (seg_id < 0)
|
|
/* omitted segment */
|
|
return;
|
|
|
|
seg = &swr->svp->segs[seg_id];
|
|
n_points = seg->n_points++;
|
|
if (swr->n_points_max[seg_id] == n_points)
|
|
art_expand (seg->points, ArtPoint, swr->n_points_max[seg_id]);
|
|
seg->points[n_points].x = x;
|
|
seg->points[n_points].y = y;
|
|
if (x < seg->bbox.x0)
|
|
seg->bbox.x0 = x;
|
|
if (x > seg->bbox.x1)
|
|
seg->bbox.x1 = x;
|
|
seg->bbox.y1 = y;
|
|
}
|
|
|
|
static void
|
|
art_svp_writer_rewind_close_segment (ArtSvpWriter *self, int seg_id)
|
|
{
|
|
/* Not needed for this simple implementation. A potential future
|
|
optimization is to merge segments that can be merged safely. */
|
|
#ifdef SANITYCHECK
|
|
ArtSvpWriterRewind *swr = (ArtSvpWriterRewind *)self;
|
|
ArtSVPSeg *seg;
|
|
|
|
if (seg_id >= 0)
|
|
{
|
|
seg = &swr->svp->segs[seg_id];
|
|
if (seg->n_points < 2)
|
|
art_warn ("*** closing segment %d with only %d point%s\n",
|
|
seg_id, seg->n_points, seg->n_points == 1 ? "" : "s");
|
|
}
|
|
#endif
|
|
|
|
#ifdef VERBOSE
|
|
art_dprint ("swr close_segment: %d\n", seg_id);
|
|
#endif
|
|
}
|
|
|
|
ArtSVP *
|
|
art_svp_writer_rewind_reap (ArtSvpWriter *self)
|
|
{
|
|
ArtSvpWriterRewind *swr = (ArtSvpWriterRewind *)self;
|
|
ArtSVP *result = swr->svp;
|
|
|
|
art_free (swr->n_points_max);
|
|
art_free (swr);
|
|
return result;
|
|
}
|
|
|
|
ArtSvpWriter *
|
|
art_svp_writer_rewind_new (ArtWindRule rule)
|
|
{
|
|
ArtSvpWriterRewind *result = art_new (ArtSvpWriterRewind, 1);
|
|
|
|
result->super.add_segment = art_svp_writer_rewind_add_segment;
|
|
result->super.add_point = art_svp_writer_rewind_add_point;
|
|
result->super.close_segment = art_svp_writer_rewind_close_segment;
|
|
|
|
result->rule = rule;
|
|
result->n_segs_max = 16;
|
|
result->svp = art_alloc (sizeof(ArtSVP) +
|
|
(result->n_segs_max - 1) * sizeof(ArtSVPSeg));
|
|
result->svp->n_segs = 0;
|
|
result->n_points_max = art_new (int, result->n_segs_max);
|
|
|
|
return &result->super;
|
|
}
|
|
|
|
/* Now, data structures for the active list */
|
|
|
|
typedef struct _ArtActiveSeg ArtActiveSeg;
|
|
|
|
/* Note: BNEG is 1 for \ lines, and 0 for /. Thus,
|
|
x[(flags & BNEG) ^ 1] <= x[flags & BNEG] */
|
|
#define ART_ACTIVE_FLAGS_BNEG 1
|
|
|
|
/* This flag is set if the segment has been inserted into the active
|
|
list. */
|
|
#define ART_ACTIVE_FLAGS_IN_ACTIVE 2
|
|
|
|
/* This flag is set when the segment is to be deleted in the
|
|
horiz commit process. */
|
|
#define ART_ACTIVE_FLAGS_DEL 4
|
|
|
|
/* This flag is set if the seg_id is a valid output segment. */
|
|
#define ART_ACTIVE_FLAGS_OUT 8
|
|
|
|
/* This flag is set if the segment is in the horiz list. */
|
|
#define ART_ACTIVE_FLAGS_IN_HORIZ 16
|
|
|
|
struct _ArtActiveSeg {
|
|
int flags;
|
|
int wind_left, delta_wind;
|
|
ArtActiveSeg *left, *right; /* doubly linked list structure */
|
|
|
|
const ArtSVPSeg *in_seg;
|
|
int in_curs;
|
|
|
|
double x[2];
|
|
double y0, y1;
|
|
double a, b, c; /* line equation; ax+by+c = 0 for the line, a^2 + b^2 = 1,
|
|
and a>0 */
|
|
|
|
/* bottom point and intersection point stack */
|
|
int n_stack;
|
|
int n_stack_max;
|
|
ArtPoint *stack;
|
|
|
|
/* horiz commit list */
|
|
ArtActiveSeg *horiz_left, *horiz_right;
|
|
double horiz_x;
|
|
int horiz_delta_wind;
|
|
int seg_id;
|
|
};
|
|
|
|
typedef struct _ArtIntersectCtx ArtIntersectCtx;
|
|
|
|
struct _ArtIntersectCtx {
|
|
const ArtSVP *in;
|
|
ArtSvpWriter *out;
|
|
|
|
ArtPriQ *pq;
|
|
|
|
ArtActiveSeg *active_head;
|
|
|
|
double y;
|
|
ArtActiveSeg *horiz_first;
|
|
ArtActiveSeg *horiz_last;
|
|
|
|
/* segment index of next input segment to be added to pri q */
|
|
int in_curs;
|
|
};
|
|
|
|
#define EPSILON_A 1e-5 /* Threshold for breaking lines at point insertions */
|
|
|
|
/**
|
|
* art_svp_intersect_setup_seg: Set up an active segment from input segment.
|
|
* @seg: Active segment.
|
|
* @pri_pt: Priority queue point to initialize.
|
|
*
|
|
* Sets the x[], a, b, c, flags, and stack fields according to the
|
|
* line from the current cursor value. Sets the priority queue point
|
|
* to the bottom point of this line. Also advances the input segment
|
|
* cursor.
|
|
**/
|
|
static void
|
|
art_svp_intersect_setup_seg (ArtActiveSeg *seg, ArtPriPoint *pri_pt)
|
|
{
|
|
const ArtSVPSeg *in_seg = seg->in_seg;
|
|
int in_curs = seg->in_curs++;
|
|
double x0, y0, x1, y1;
|
|
double dx, dy, s;
|
|
double a, b, r2;
|
|
|
|
x0 = in_seg->points[in_curs].x;
|
|
y0 = in_seg->points[in_curs].y;
|
|
x1 = in_seg->points[in_curs + 1].x;
|
|
y1 = in_seg->points[in_curs + 1].y;
|
|
pri_pt->x = x1;
|
|
pri_pt->y = y1;
|
|
dx = x1 - x0;
|
|
dy = y1 - y0;
|
|
r2 = dx * dx + dy * dy;
|
|
s = r2 == 0 ? 1 : 1 / sqrt (r2);
|
|
seg->a = a = dy * s;
|
|
seg->b = b = -dx * s;
|
|
seg->c = -(a * x0 + b * y0);
|
|
seg->flags = (seg->flags & ~ART_ACTIVE_FLAGS_BNEG) | (dx > 0);
|
|
seg->x[0] = x0;
|
|
seg->x[1] = x1;
|
|
seg->y0 = y0;
|
|
seg->y1 = y1;
|
|
seg->n_stack = 1;
|
|
seg->stack[0].x = x1;
|
|
seg->stack[0].y = y1;
|
|
}
|
|
|
|
/**
|
|
* art_svp_intersect_add_horiz: Add point to horizontal list.
|
|
* @ctx: Intersector context.
|
|
* @seg: Segment with point to insert into horizontal list.
|
|
*
|
|
* Inserts @seg into horizontal list, keeping it in ascending horiz_x
|
|
* order.
|
|
*
|
|
* Note: the horiz_commit routine processes "clusters" of segs in the
|
|
* horiz list, all sharing the same horiz_x value. The cluster is
|
|
* processed in active list order, rather than horiz list order. Thus,
|
|
* the order of segs in the horiz list sharing the same horiz_x
|
|
* _should_ be irrelevant. Even so, we use b as a secondary sorting key,
|
|
* as a "belt and suspenders" defensive coding tactic.
|
|
**/
|
|
static void
|
|
art_svp_intersect_add_horiz (ArtIntersectCtx *ctx, ArtActiveSeg *seg)
|
|
{
|
|
ArtActiveSeg **pp = &ctx->horiz_last;
|
|
ArtActiveSeg *place;
|
|
ArtActiveSeg *place_right = NULL;
|
|
|
|
|
|
#ifdef CHEAP_SANITYCHECK
|
|
if (seg->flags & ART_ACTIVE_FLAGS_IN_HORIZ)
|
|
{
|
|
art_warn ("*** attempt to put segment in horiz list twice\n");
|
|
return;
|
|
}
|
|
seg->flags |= ART_ACTIVE_FLAGS_IN_HORIZ;
|
|
#endif
|
|
|
|
#ifdef VERBOSE
|
|
art_dprint ("add_horiz %lx, x = %g\n", (unsigned long) seg, seg->horiz_x);
|
|
#endif
|
|
for (place = *pp; place != NULL && (place->horiz_x > seg->horiz_x ||
|
|
(place->horiz_x == seg->horiz_x &&
|
|
place->b < seg->b));
|
|
place = *pp)
|
|
{
|
|
place_right = place;
|
|
pp = &place->horiz_left;
|
|
}
|
|
*pp = seg;
|
|
seg->horiz_left = place;
|
|
seg->horiz_right = place_right;
|
|
if (place == NULL)
|
|
ctx->horiz_first = seg;
|
|
else
|
|
place->horiz_right = seg;
|
|
}
|
|
|
|
static void
|
|
art_svp_intersect_push_pt (ArtIntersectCtx *ctx, ArtActiveSeg *seg,
|
|
double x, double y)
|
|
{
|
|
ArtPriPoint *pri_pt;
|
|
int n_stack = seg->n_stack;
|
|
|
|
if (n_stack == seg->n_stack_max)
|
|
art_expand (seg->stack, ArtPoint, seg->n_stack_max);
|
|
seg->stack[n_stack].x = x;
|
|
seg->stack[n_stack].y = y;
|
|
seg->n_stack++;
|
|
|
|
seg->x[1] = x;
|
|
seg->y1 = y;
|
|
|
|
pri_pt = art_new (ArtPriPoint, 1);
|
|
pri_pt->x = x;
|
|
pri_pt->y = y;
|
|
pri_pt->user_data = seg;
|
|
art_pri_insert (ctx->pq, pri_pt);
|
|
}
|
|
|
|
/**
|
|
* art_svp_intersect_break: Break an active segment.
|
|
*
|
|
* Note: y must be greater than the top point's y, and less than
|
|
* the bottom's.
|
|
*
|
|
* Return value: x coordinate of break point.
|
|
*/
|
|
static double
|
|
art_svp_intersect_break (ArtIntersectCtx *ctx, ArtActiveSeg *seg,
|
|
double y)
|
|
{
|
|
double x0, y0, x1, y1;
|
|
const ArtSVPSeg *in_seg = seg->in_seg;
|
|
int in_curs = seg->in_curs;
|
|
double x;
|
|
|
|
x0 = in_seg->points[in_curs - 1].x;
|
|
y0 = in_seg->points[in_curs - 1].y;
|
|
x1 = in_seg->points[in_curs].x;
|
|
y1 = in_seg->points[in_curs].y;
|
|
x = x0 + (x1 - x0) * ((y - y0) / (y1 - y0));
|
|
|
|
/* I think we can count on min(x0, x1) <= x <= max(x0, x1) with sane
|
|
arithmetic, but it might be worthwhile to check just in case. */
|
|
|
|
if (y > ctx->y)
|
|
art_svp_intersect_push_pt (ctx, seg, x, y);
|
|
else
|
|
{
|
|
seg->x[0] = x;
|
|
seg->y0 = y;
|
|
seg->horiz_x = x;
|
|
art_svp_intersect_add_horiz (ctx, seg);
|
|
}
|
|
|
|
return x;
|
|
}
|
|
|
|
/**
|
|
* art_svp_intersect_add_point: Add a point, breaking nearby neighbors.
|
|
* @ctx: Intersector context.
|
|
* @x: X coordinate of point to add.
|
|
* @y: Y coordinate of point to add.
|
|
* @seg: "nearby" segment, or NULL if leftmost.
|
|
*
|
|
* Return value: Segment immediately to the left of the new point, or
|
|
* NULL if the new point is leftmost.
|
|
**/
|
|
static ArtActiveSeg *
|
|
art_svp_intersect_add_point (ArtIntersectCtx *ctx, double x, double y,
|
|
ArtActiveSeg *seg)
|
|
{
|
|
ArtActiveSeg *left, *right;
|
|
double x_min = x, x_max = x;
|
|
art_boolean left_live, right_live;
|
|
double d;
|
|
double new_x;
|
|
ArtActiveSeg *test, *result = NULL;
|
|
double x_test;
|
|
|
|
left = seg;
|
|
if (left == NULL)
|
|
right = ctx->active_head;
|
|
else
|
|
right = left->right;
|
|
left_live = (left != NULL);
|
|
right_live = (right != NULL);
|
|
while (left_live || right_live)
|
|
{
|
|
if (left_live)
|
|
{
|
|
if (x <= left->x[left->flags & ART_ACTIVE_FLAGS_BNEG] &&
|
|
/* It may be that one of these conjuncts turns out to be always
|
|
true. We test both anyway, to be defensive. */
|
|
y != left->y0 && y < left->y1)
|
|
{
|
|
d = x_min * left->a + y * left->b + left->c;
|
|
if (d < EPSILON_A)
|
|
{
|
|
new_x = art_svp_intersect_break (ctx, left, y);
|
|
if (new_x > x_max)
|
|
{
|
|
x_max = new_x;
|
|
right_live = (right != NULL);
|
|
}
|
|
else if (new_x < x_min)
|
|
x_min = new_x;
|
|
left = left->left;
|
|
left_live = (left != NULL);
|
|
}
|
|
else
|
|
left_live = ART_FALSE;
|
|
}
|
|
else
|
|
left_live = ART_FALSE;
|
|
}
|
|
else if (right_live)
|
|
{
|
|
if (x <= right->x[(right->flags & ART_ACTIVE_FLAGS_BNEG) ^ 1] &&
|
|
/* It may be that one of these conjuncts turns out to be always
|
|
true. We test both anyway, to be defensive. */
|
|
y != right->y0 && y < right->y1)
|
|
{
|
|
d = x_max * right->a + y * right->b + right->c;
|
|
if (d > -EPSILON_A)
|
|
{
|
|
new_x = art_svp_intersect_break (ctx, right, y);
|
|
if (new_x < x_min)
|
|
{
|
|
x_min = new_x;
|
|
left_live = (left != NULL);
|
|
}
|
|
else if (new_x >= x_max)
|
|
x_max = new_x;
|
|
right = right->right;
|
|
right_live = (right != NULL);
|
|
}
|
|
else
|
|
right_live = ART_FALSE;
|
|
}
|
|
else
|
|
right_live = ART_FALSE;
|
|
}
|
|
}
|
|
|
|
/* Now, (left, right) defines an interval of segments broken. Sort
|
|
into ascending x order. */
|
|
test = left == NULL ? ctx->active_head : left->right;
|
|
result = left;
|
|
if (test != NULL && test != right)
|
|
{
|
|
x_test = test->x[1];
|
|
for (;;)
|
|
{
|
|
if (x_test <= x)
|
|
result = test;
|
|
test = test->right;
|
|
if (test == right)
|
|
break;
|
|
new_x = test->x[1];
|
|
if (new_x < x_test)
|
|
{
|
|
art_warn ("art_svp_intersect_add_point: non-ascending x\n");
|
|
}
|
|
x_test = new_x;
|
|
}
|
|
}
|
|
return result;
|
|
}
|
|
|
|
static void
|
|
art_svp_intersect_swap_active (ArtIntersectCtx *ctx,
|
|
ArtActiveSeg *left_seg, ArtActiveSeg *right_seg)
|
|
{
|
|
right_seg->left = left_seg->left;
|
|
if (right_seg->left != NULL)
|
|
right_seg->left->right = right_seg;
|
|
else
|
|
ctx->active_head = right_seg;
|
|
left_seg->right = right_seg->right;
|
|
if (left_seg->right != NULL)
|
|
left_seg->right->left = left_seg;
|
|
left_seg->left = right_seg;
|
|
right_seg->right = left_seg;
|
|
}
|
|
|
|
typedef enum {
|
|
ART_BREAK_LEFT = 1,
|
|
ART_BREAK_RIGHT = 2
|
|
} ArtBreakFlags;
|
|
|
|
/**
|
|
* art_svp_intersect_test_cross: Test crossing of a pair of active segments.
|
|
* @ctx: Intersector context.
|
|
* @left_seg: Left segment of the pair.
|
|
* @right_seg: Right segment of the pair.
|
|
* @break_flags: Flags indicating whether to break neighbors.
|
|
*
|
|
* Tests crossing of @left_seg and @right_seg. If there is a crossing,
|
|
* inserts the intersection point into both segments.
|
|
*
|
|
* Return value: True if the intersection took place at the current
|
|
* scan line, indicating further iteration is needed.
|
|
**/
|
|
static art_boolean
|
|
art_svp_intersect_test_cross (ArtIntersectCtx *ctx,
|
|
ArtActiveSeg *left_seg, ArtActiveSeg *right_seg,
|
|
ArtBreakFlags break_flags)
|
|
{
|
|
double left_x0, left_y0, left_x1;
|
|
double left_y1 = left_seg->y1;
|
|
double right_y1 = right_seg->y1;
|
|
double d;
|
|
|
|
const ArtSVPSeg *in_seg;
|
|
int in_curs;
|
|
double d0, d1, t;
|
|
double x, y; /* intersection point */
|
|
|
|
#ifdef VERBOSE
|
|
static int count = 0;
|
|
|
|
art_dprint ("art_svp_intersect_test_cross %lx <-> %lx: count=%d\n",
|
|
(unsigned long)left_seg, (unsigned long)right_seg, count++);
|
|
#endif
|
|
|
|
if (left_seg->y0 == right_seg->y0 && left_seg->x[0] == right_seg->x[0])
|
|
{
|
|
if (left_seg->b < right_seg->b)
|
|
{
|
|
art_svp_intersect_swap_active (ctx, left_seg, right_seg);
|
|
return ART_TRUE;
|
|
}
|
|
else
|
|
return ART_FALSE;
|
|
}
|
|
|
|
if (left_y1 < right_y1)
|
|
{
|
|
/* Test left (x1, y1) against right segment */
|
|
double left_x1 = left_seg->x[1];
|
|
|
|
if (left_x1 <
|
|
right_seg->x[(right_seg->flags & ART_ACTIVE_FLAGS_BNEG) ^ 1] ||
|
|
left_y1 == right_seg->y0)
|
|
return ART_FALSE;
|
|
d = left_x1 * right_seg->a + left_y1 * right_seg->b + right_seg->c;
|
|
if (d < -EPSILON_A)
|
|
return ART_FALSE;
|
|
else if (d < EPSILON_A)
|
|
{
|
|
double right_x1 = art_svp_intersect_break (ctx, right_seg, left_y1);
|
|
if (left_x1 <= right_x1)
|
|
return ART_FALSE;
|
|
}
|
|
}
|
|
else if (left_y1 > right_y1)
|
|
{
|
|
/* Test right (x1, y1) against left segment */
|
|
double right_x1 = right_seg->x[1];
|
|
|
|
if (right_x1 > left_seg->x[left_seg->flags & ART_ACTIVE_FLAGS_BNEG] ||
|
|
right_y1 == left_seg->y0)
|
|
return ART_FALSE;
|
|
d = right_x1 * left_seg->a + right_y1 * left_seg->b + left_seg->c;
|
|
if (d > EPSILON_A)
|
|
return ART_FALSE;
|
|
else if (d > -EPSILON_A)
|
|
{
|
|
double left_x1 = art_svp_intersect_break (ctx, left_seg, right_y1);
|
|
if (left_x1 <= right_x1)
|
|
return ART_FALSE;
|
|
}
|
|
}
|
|
else /* left_y1 == right_y1 */
|
|
{
|
|
double left_x1 = left_seg->x[1];
|
|
double right_x1 = right_seg->x[1];
|
|
|
|
if (left_x1 <= right_x1)
|
|
return ART_FALSE;
|
|
}
|
|
|
|
/* The segments cross. Find the intersection point. */
|
|
|
|
in_seg = left_seg->in_seg;
|
|
in_curs = left_seg->in_curs;
|
|
left_x0 = in_seg->points[in_curs - 1].x;
|
|
left_y0 = in_seg->points[in_curs - 1].y;
|
|
left_x1 = in_seg->points[in_curs].x;
|
|
left_y1 = in_seg->points[in_curs].y;
|
|
d0 = left_x0 * right_seg->a + left_y0 * right_seg->b + right_seg->c;
|
|
d1 = left_x1 * right_seg->a + left_y1 * right_seg->b + right_seg->c;
|
|
if (d0 == d1)
|
|
{
|
|
x = left_x0;
|
|
y = left_y0;
|
|
}
|
|
else
|
|
{
|
|
/* Is this division always safe? It could possibly overflow. */
|
|
t = d0 / (d0 - d1);
|
|
if (t <= 0)
|
|
{
|
|
x = left_x0;
|
|
y = left_y0;
|
|
}
|
|
else if (t >= 1)
|
|
{
|
|
x = left_x1;
|
|
y = left_y1;
|
|
}
|
|
else
|
|
{
|
|
x = left_x0 + t * (left_x1 - left_x0);
|
|
y = left_y0 + t * (left_y1 - left_y0);
|
|
}
|
|
}
|
|
|
|
/* Make sure intersection point is within bounds of right seg. */
|
|
if (y < right_seg->y0)
|
|
{
|
|
x = right_seg->x[0];
|
|
y = right_seg->y0;
|
|
}
|
|
else if (y > right_seg->y1)
|
|
{
|
|
x = right_seg->x[1];
|
|
y = right_seg->y1;
|
|
}
|
|
else if (x < right_seg->x[(right_seg->flags & ART_ACTIVE_FLAGS_BNEG) ^ 1])
|
|
x = right_seg->x[(right_seg->flags & ART_ACTIVE_FLAGS_BNEG) ^ 1];
|
|
else if (x > right_seg->x[right_seg->flags & ART_ACTIVE_FLAGS_BNEG])
|
|
x = right_seg->x[right_seg->flags & ART_ACTIVE_FLAGS_BNEG];
|
|
|
|
if (y == left_seg->y0)
|
|
{
|
|
if (y != right_seg->y0)
|
|
{
|
|
#ifdef VERBOSE
|
|
art_dprint ("art_svp_intersect_test_cross: intersection (%g, %g) matches former y0 of %lx, %lx\n",
|
|
x, y, (unsigned long)left_seg, (unsigned long)right_seg);
|
|
#endif
|
|
art_svp_intersect_push_pt (ctx, right_seg, x, y);
|
|
if ((break_flags & ART_BREAK_RIGHT) && right_seg->right != NULL)
|
|
art_svp_intersect_add_point (ctx, x, y, right_seg->right);
|
|
}
|
|
else
|
|
{
|
|
/* Intersection takes place at current scan line; process
|
|
immediately rather than queueing intersection point into
|
|
priq. */
|
|
|
|
/* Choose "most vertical" segement */
|
|
if (left_seg->a > right_seg->a)
|
|
x = left_seg->x[0];
|
|
else
|
|
x = right_seg->x[0];
|
|
/* todo: fudge x */
|
|
|
|
art_svp_intersect_swap_active (ctx, left_seg, right_seg);
|
|
return ART_TRUE;
|
|
}
|
|
}
|
|
else if (y == right_seg->y0)
|
|
{
|
|
#ifdef VERBOSE
|
|
art_dprint ("*** art_svp_intersect_test_cross: intersection (%g, %g) matches latter y0 of %lx, %lx\n",
|
|
x, y, (unsigned long)left_seg, (unsigned long)right_seg);
|
|
#endif
|
|
art_svp_intersect_push_pt (ctx, left_seg, x, y);
|
|
if ((break_flags & ART_BREAK_LEFT) && left_seg->left != NULL)
|
|
art_svp_intersect_add_point (ctx, x, y, left_seg->left);
|
|
}
|
|
else
|
|
{
|
|
#ifdef VERBOSE
|
|
art_dprint ("Inserting (%g, %g) into %lx, %lx\n",
|
|
x, y, (unsigned long)left_seg, (unsigned long)right_seg);
|
|
#endif
|
|
/* Insert the intersection point into both segments. */
|
|
art_svp_intersect_push_pt (ctx, left_seg, x, y);
|
|
art_svp_intersect_push_pt (ctx, right_seg, x, y);
|
|
if ((break_flags & ART_BREAK_LEFT) && left_seg->left != NULL)
|
|
art_svp_intersect_add_point (ctx, x, y, left_seg->left);
|
|
if ((break_flags & ART_BREAK_RIGHT) && right_seg->right != NULL)
|
|
art_svp_intersect_add_point (ctx, x, y, right_seg->right);
|
|
}
|
|
return ART_FALSE;
|
|
}
|
|
|
|
/**
|
|
* art_svp_intersect_active_delete: Delete segment from active list.
|
|
* @ctx: Intersection context.
|
|
* @seg: Segment to delete.
|
|
*
|
|
* Deletes @seg from the active list.
|
|
**/
|
|
static /* todo inline */ void
|
|
art_svp_intersect_active_delete (ArtIntersectCtx *ctx, ArtActiveSeg *seg)
|
|
{
|
|
ArtActiveSeg *left = seg->left, *right = seg->right;
|
|
|
|
if (left != NULL)
|
|
left->right = right;
|
|
else
|
|
ctx->active_head = right;
|
|
if (right != NULL)
|
|
right->left = left;
|
|
}
|
|
|
|
/**
|
|
* art_svp_intersect_active_free: Free an active segment.
|
|
* @seg: Segment to delete.
|
|
*
|
|
* Frees @seg.
|
|
**/
|
|
static /* todo inline */ void
|
|
art_svp_intersect_active_free (ArtActiveSeg *seg)
|
|
{
|
|
art_free (seg->stack);
|
|
#ifdef VERBOSE
|
|
art_dprint ("Freeing %lx\n", (unsigned long) seg);
|
|
#endif
|
|
art_free (seg);
|
|
}
|
|
|
|
/**
|
|
* art_svp_intersect_insert_cross: Test crossings of newly inserted line.
|
|
*
|
|
* Tests @seg against its left and right neighbors for intersections.
|
|
* Precondition: the line in @seg is not purely horizontal.
|
|
**/
|
|
static void
|
|
art_svp_intersect_insert_cross (ArtIntersectCtx *ctx,
|
|
ArtActiveSeg *seg)
|
|
{
|
|
ArtActiveSeg *left = seg, *right = seg;
|
|
|
|
for (;;)
|
|
{
|
|
if (left != NULL)
|
|
{
|
|
ArtActiveSeg *leftc;
|
|
|
|
for (leftc = left->left; leftc != NULL; leftc = leftc->left)
|
|
if (!(leftc->flags & ART_ACTIVE_FLAGS_DEL))
|
|
break;
|
|
if (leftc != NULL &&
|
|
art_svp_intersect_test_cross (ctx, leftc, left,
|
|
ART_BREAK_LEFT))
|
|
{
|
|
if (left == right || right == NULL)
|
|
right = left->right;
|
|
}
|
|
else
|
|
{
|
|
left = NULL;
|
|
}
|
|
}
|
|
else if (right != NULL && right->right != NULL)
|
|
{
|
|
ArtActiveSeg *rightc;
|
|
|
|
for (rightc = right->right; rightc != NULL; rightc = rightc->right)
|
|
if (!(rightc->flags & ART_ACTIVE_FLAGS_DEL))
|
|
break;
|
|
if (rightc != NULL &&
|
|
art_svp_intersect_test_cross (ctx, right, rightc,
|
|
ART_BREAK_RIGHT))
|
|
{
|
|
if (left == right || left == NULL)
|
|
left = right->left;
|
|
}
|
|
else
|
|
{
|
|
right = NULL;
|
|
}
|
|
}
|
|
else
|
|
break;
|
|
}
|
|
}
|
|
|
|
/**
|
|
* art_svp_intersect_horiz: Add horizontal line segment.
|
|
* @ctx: Intersector context.
|
|
* @seg: Segment on which to add horizontal line.
|
|
* @x0: Old x position.
|
|
* @x1: New x position.
|
|
*
|
|
* Adds a horizontal line from @x0 to @x1, and updates the current
|
|
* location of @seg to @x1.
|
|
**/
|
|
static void
|
|
art_svp_intersect_horiz (ArtIntersectCtx *ctx, ArtActiveSeg *seg,
|
|
double x0, double x1)
|
|
{
|
|
ArtActiveSeg *hs;
|
|
|
|
if (x0 == x1)
|
|
return;
|
|
|
|
hs = art_new (ArtActiveSeg, 1);
|
|
|
|
hs->flags = ART_ACTIVE_FLAGS_DEL | (seg->flags & ART_ACTIVE_FLAGS_OUT);
|
|
if (seg->flags & ART_ACTIVE_FLAGS_OUT)
|
|
{
|
|
ArtSvpWriter *swr = ctx->out;
|
|
|
|
swr->add_point (swr, seg->seg_id, x0, ctx->y);
|
|
}
|
|
hs->seg_id = seg->seg_id;
|
|
hs->horiz_x = x0;
|
|
hs->horiz_delta_wind = seg->delta_wind;
|
|
hs->stack = NULL;
|
|
seg->horiz_delta_wind -= seg->delta_wind;
|
|
|
|
art_svp_intersect_add_horiz (ctx, hs);
|
|
|
|
if (x0 > x1)
|
|
{
|
|
ArtActiveSeg *left;
|
|
art_boolean first = ART_TRUE;
|
|
|
|
for (left = seg->left; left != NULL; left = seg->left)
|
|
{
|
|
int left_bneg = left->flags & ART_ACTIVE_FLAGS_BNEG;
|
|
|
|
if (left->x[left_bneg] <= x1)
|
|
break;
|
|
if (left->x[left_bneg ^ 1] <= x1 &&
|
|
x1 * left->a + ctx->y * left->b + left->c >= 0)
|
|
break;
|
|
if (left->y0 != ctx->y && left->y1 != ctx->y)
|
|
{
|
|
art_svp_intersect_break (ctx, left, ctx->y);
|
|
}
|
|
#ifdef VERBOSE
|
|
art_dprint ("x0=%g > x1=%g, swapping %lx, %lx\n",
|
|
x0, x1, (unsigned long)left, (unsigned long)seg);
|
|
#endif
|
|
art_svp_intersect_swap_active (ctx, left, seg);
|
|
if (first && left->right != NULL)
|
|
{
|
|
art_svp_intersect_test_cross (ctx, left, left->right,
|
|
ART_BREAK_LEFT);
|
|
first = ART_FALSE;
|
|
}
|
|
}
|
|
}
|
|
else
|
|
{
|
|
ArtActiveSeg *right;
|
|
art_boolean first = ART_TRUE;
|
|
|
|
for (right = seg->right; right != NULL; right = seg->right)
|
|
{
|
|
int right_bneg = right->flags & ART_ACTIVE_FLAGS_BNEG;
|
|
|
|
if (right->x[right_bneg ^ 1] >= x1)
|
|
break;
|
|
if (right->x[right_bneg] >= x1 &&
|
|
x1 * right->a + ctx->y * right->b + right->c <= 0)
|
|
break;
|
|
if (right->y0 != ctx->y && right->y1 != ctx->y)
|
|
{
|
|
art_svp_intersect_break (ctx, right, ctx->y);
|
|
}
|
|
#ifdef VERBOSE
|
|
art_dprint ("[right]x0=%g < x1=%g, swapping %lx, %lx\n",
|
|
x0, x1, (unsigned long)seg, (unsigned long)right);
|
|
#endif
|
|
art_svp_intersect_swap_active (ctx, seg, right);
|
|
if (first && right->left != NULL)
|
|
{
|
|
art_svp_intersect_test_cross (ctx, right->left, right,
|
|
ART_BREAK_RIGHT);
|
|
first = ART_FALSE;
|
|
}
|
|
}
|
|
}
|
|
|
|
seg->x[0] = x1;
|
|
seg->x[1] = x1;
|
|
seg->horiz_x = x1;
|
|
seg->flags &= ~ART_ACTIVE_FLAGS_OUT;
|
|
}
|
|
|
|
/**
|
|
* art_svp_intersect_insert_line: Insert a line into the active list.
|
|
* @ctx: Intersector context.
|
|
* @seg: Segment containing line to insert.
|
|
*
|
|
* Inserts the line into the intersector context, taking care of any
|
|
* intersections, and adding the appropriate horizontal points to the
|
|
* active list.
|
|
**/
|
|
static void
|
|
art_svp_intersect_insert_line (ArtIntersectCtx *ctx, ArtActiveSeg *seg)
|
|
{
|
|
if (seg->y1 == seg->y0)
|
|
{
|
|
#ifdef VERBOSE
|
|
art_dprint ("art_svp_intersect_insert_line: %lx is horizontal\n",
|
|
(unsigned long)seg);
|
|
#endif
|
|
art_svp_intersect_horiz (ctx, seg, seg->x[0], seg->x[1]);
|
|
}
|
|
else
|
|
{
|
|
art_svp_intersect_insert_cross (ctx, seg);
|
|
art_svp_intersect_add_horiz (ctx, seg);
|
|
}
|
|
}
|
|
|
|
static void
|
|
art_svp_intersect_process_intersection (ArtIntersectCtx *ctx,
|
|
ArtActiveSeg *seg)
|
|
{
|
|
int n_stack = --seg->n_stack;
|
|
seg->x[1] = seg->stack[n_stack - 1].x;
|
|
seg->y1 = seg->stack[n_stack - 1].y;
|
|
seg->x[0] = seg->stack[n_stack].x;
|
|
seg->y0 = seg->stack[n_stack].y;
|
|
seg->horiz_x = seg->x[0];
|
|
art_svp_intersect_insert_line (ctx, seg);
|
|
}
|
|
|
|
static void
|
|
art_svp_intersect_advance_cursor (ArtIntersectCtx *ctx, ArtActiveSeg *seg,
|
|
ArtPriPoint *pri_pt)
|
|
{
|
|
const ArtSVPSeg *in_seg = seg->in_seg;
|
|
int in_curs = seg->in_curs;
|
|
ArtSvpWriter *swr = seg->flags & ART_ACTIVE_FLAGS_OUT ? ctx->out : NULL;
|
|
|
|
if (swr != NULL)
|
|
swr->add_point (swr, seg->seg_id, seg->x[1], seg->y1);
|
|
if (in_curs + 1 == in_seg->n_points)
|
|
{
|
|
ArtActiveSeg *left = seg->left, *right = seg->right;
|
|
|
|
#if 0
|
|
if (swr != NULL)
|
|
swr->close_segment (swr, seg->seg_id);
|
|
seg->flags &= ~ART_ACTIVE_FLAGS_OUT;
|
|
#endif
|
|
seg->flags |= ART_ACTIVE_FLAGS_DEL;
|
|
art_svp_intersect_add_horiz (ctx, seg);
|
|
art_svp_intersect_active_delete (ctx, seg);
|
|
if (left != NULL && right != NULL)
|
|
art_svp_intersect_test_cross (ctx, left, right,
|
|
ART_BREAK_LEFT | ART_BREAK_RIGHT);
|
|
art_free (pri_pt);
|
|
}
|
|
else
|
|
{
|
|
seg->horiz_x = seg->x[1];
|
|
|
|
art_svp_intersect_setup_seg (seg, pri_pt);
|
|
art_pri_insert (ctx->pq, pri_pt);
|
|
art_svp_intersect_insert_line (ctx, seg);
|
|
}
|
|
}
|
|
|
|
static void
|
|
art_svp_intersect_add_seg (ArtIntersectCtx *ctx, const ArtSVPSeg *in_seg)
|
|
{
|
|
ArtActiveSeg *seg = art_new (ArtActiveSeg, 1);
|
|
ArtActiveSeg *test;
|
|
double x0, y0;
|
|
ArtActiveSeg *beg_range;
|
|
ArtActiveSeg *last = NULL;
|
|
ArtActiveSeg *left, *right;
|
|
ArtPriPoint *pri_pt = art_new (ArtPriPoint, 1);
|
|
|
|
seg->flags = 0;
|
|
seg->in_seg = in_seg;
|
|
seg->in_curs = 0;
|
|
|
|
seg->n_stack_max = 4;
|
|
seg->stack = art_new (ArtPoint, seg->n_stack_max);
|
|
|
|
seg->horiz_delta_wind = 0;
|
|
|
|
pri_pt->user_data = seg;
|
|
art_svp_intersect_setup_seg (seg, pri_pt);
|
|
art_pri_insert (ctx->pq, pri_pt);
|
|
|
|
/* Find insertion place for new segment */
|
|
/* This is currently a left-to-right scan, but should be replaced
|
|
with a binary search as soon as it's validated. */
|
|
|
|
x0 = in_seg->points[0].x;
|
|
y0 = in_seg->points[0].y;
|
|
beg_range = NULL;
|
|
for (test = ctx->active_head; test != NULL; test = test->right)
|
|
{
|
|
double d;
|
|
int test_bneg = test->flags & ART_ACTIVE_FLAGS_BNEG;
|
|
|
|
if (x0 < test->x[test_bneg])
|
|
{
|
|
if (x0 < test->x[test_bneg ^ 1])
|
|
break;
|
|
d = x0 * test->a + y0 * test->b + test->c;
|
|
if (d < 0)
|
|
break;
|
|
}
|
|
last = test;
|
|
}
|
|
|
|
left = art_svp_intersect_add_point (ctx, x0, y0, last);
|
|
seg->left = left;
|
|
if (left == NULL)
|
|
{
|
|
right = ctx->active_head;
|
|
ctx->active_head = seg;
|
|
}
|
|
else
|
|
{
|
|
right = left->right;
|
|
left->right = seg;
|
|
}
|
|
seg->right = right;
|
|
if (right != NULL)
|
|
right->left = seg;
|
|
|
|
seg->delta_wind = in_seg->dir ? 1 : -1;
|
|
seg->horiz_x = x0;
|
|
|
|
art_svp_intersect_insert_line (ctx, seg);
|
|
}
|
|
|
|
#ifdef SANITYCHECK
|
|
static void
|
|
art_svp_intersect_sanitycheck_winding (ArtIntersectCtx *ctx)
|
|
{
|
|
#if 0
|
|
/* At this point, we seem to be getting false positives, so it's
|
|
turned off for now. */
|
|
|
|
ArtActiveSeg *seg;
|
|
int winding_number = 0;
|
|
|
|
for (seg = ctx->active_head; seg != NULL; seg = seg->right)
|
|
{
|
|
/* Check winding number consistency. */
|
|
if (seg->flags & ART_ACTIVE_FLAGS_OUT)
|
|
{
|
|
if (winding_number != seg->wind_left)
|
|
art_warn ("*** art_svp_intersect_sanitycheck_winding: seg %lx has wind_left of %d, expected %d\n",
|
|
(unsigned long) seg, seg->wind_left, winding_number);
|
|
winding_number = seg->wind_left + seg->delta_wind;
|
|
}
|
|
}
|
|
if (winding_number != 0)
|
|
art_warn ("*** art_svp_intersect_sanitycheck_winding: non-balanced winding number %d\n",
|
|
winding_number);
|
|
#endif
|
|
}
|
|
#endif
|
|
|
|
/**
|
|
* art_svp_intersect_horiz_commit: Commit points in horiz list to output.
|
|
* @ctx: Intersection context.
|
|
*
|
|
* The main function of the horizontal commit is to output new
|
|
* points to the output writer.
|
|
*
|
|
* This "commit" pass is also where winding numbers are assigned,
|
|
* because doing it here provides much greater tolerance for inputs
|
|
* which are not in strict SVP order.
|
|
*
|
|
* Each cluster in the horiz_list contains both segments that are in
|
|
* the active list (ART_ACTIVE_FLAGS_DEL is false) and that are not,
|
|
* and are scheduled to be deleted (ART_ACTIVE_FLAGS_DEL is true). We
|
|
* need to deal with both.
|
|
**/
|
|
static void
|
|
art_svp_intersect_horiz_commit (ArtIntersectCtx *ctx)
|
|
{
|
|
ArtActiveSeg *seg;
|
|
int winding_number = 0; /* initialization just to avoid warning */
|
|
int horiz_wind = 0;
|
|
double last_x = 0; /* initialization just to avoid warning */
|
|
|
|
#ifdef VERBOSE
|
|
art_dprint ("art_svp_intersect_horiz_commit: y=%g\n", ctx->y);
|
|
for (seg = ctx->horiz_first; seg != NULL; seg = seg->horiz_right)
|
|
art_dprint (" %lx: %g %+d\n",
|
|
(unsigned long)seg, seg->horiz_x, seg->horiz_delta_wind);
|
|
#endif
|
|
|
|
/* Output points to svp writer. */
|
|
for (seg = ctx->horiz_first; seg != NULL;)
|
|
{
|
|
/* Find a cluster with common horiz_x, */
|
|
ArtActiveSeg *curs;
|
|
double x = seg->horiz_x;
|
|
|
|
/* Generate any horizontal segments. */
|
|
if (horiz_wind != 0)
|
|
{
|
|
ArtSvpWriter *swr = ctx->out;
|
|
int seg_id;
|
|
|
|
seg_id = swr->add_segment (swr, winding_number, horiz_wind,
|
|
last_x, ctx->y);
|
|
swr->add_point (swr, seg_id, x, ctx->y);
|
|
swr->close_segment (swr, seg_id);
|
|
}
|
|
|
|
/* Find first active segment in cluster. */
|
|
|
|
for (curs = seg; curs != NULL && curs->horiz_x == x;
|
|
curs = curs->horiz_right)
|
|
if (!(curs->flags & ART_ACTIVE_FLAGS_DEL))
|
|
break;
|
|
|
|
if (curs != NULL && curs->horiz_x == x)
|
|
{
|
|
/* There exists at least one active segment in this cluster. */
|
|
|
|
/* Find beginning of cluster. */
|
|
for (; curs->left != NULL; curs = curs->left)
|
|
if (curs->left->horiz_x != x)
|
|
break;
|
|
|
|
if (curs->left != NULL)
|
|
winding_number = curs->left->wind_left + curs->left->delta_wind;
|
|
else
|
|
winding_number = 0;
|
|
|
|
do
|
|
{
|
|
#ifdef VERBOSE
|
|
art_dprint (" winding_number = %d += %d\n",
|
|
winding_number, curs->delta_wind);
|
|
#endif
|
|
if (!(curs->flags & ART_ACTIVE_FLAGS_OUT) ||
|
|
curs->wind_left != winding_number)
|
|
{
|
|
ArtSvpWriter *swr = ctx->out;
|
|
|
|
if (curs->flags & ART_ACTIVE_FLAGS_OUT)
|
|
{
|
|
swr->add_point (swr, curs->seg_id,
|
|
curs->horiz_x, ctx->y);
|
|
swr->close_segment (swr, curs->seg_id);
|
|
}
|
|
|
|
curs->seg_id = swr->add_segment (swr, winding_number,
|
|
curs->delta_wind,
|
|
x, ctx->y);
|
|
curs->flags |= ART_ACTIVE_FLAGS_OUT;
|
|
}
|
|
curs->wind_left = winding_number;
|
|
winding_number += curs->delta_wind;
|
|
curs = curs->right;
|
|
}
|
|
while (curs != NULL && curs->horiz_x == x);
|
|
}
|
|
|
|
/* Skip past cluster. */
|
|
do
|
|
{
|
|
ArtActiveSeg *next = seg->horiz_right;
|
|
|
|
seg->flags &= ~ART_ACTIVE_FLAGS_IN_HORIZ;
|
|
horiz_wind += seg->horiz_delta_wind;
|
|
seg->horiz_delta_wind = 0;
|
|
if (seg->flags & ART_ACTIVE_FLAGS_DEL)
|
|
{
|
|
if (seg->flags & ART_ACTIVE_FLAGS_OUT)
|
|
{
|
|
ArtSvpWriter *swr = ctx->out;
|
|
swr->close_segment (swr, seg->seg_id);
|
|
}
|
|
art_svp_intersect_active_free (seg);
|
|
}
|
|
seg = next;
|
|
}
|
|
while (seg != NULL && seg->horiz_x == x);
|
|
|
|
last_x = x;
|
|
}
|
|
ctx->horiz_first = NULL;
|
|
ctx->horiz_last = NULL;
|
|
#ifdef SANITYCHECK
|
|
art_svp_intersect_sanitycheck_winding (ctx);
|
|
#endif
|
|
}
|
|
|
|
#ifdef VERBOSE
|
|
static void
|
|
art_svp_intersect_print_active (ArtIntersectCtx *ctx)
|
|
{
|
|
ArtActiveSeg *seg;
|
|
|
|
art_dprint ("Active list (y = %g):\n", ctx->y);
|
|
for (seg = ctx->active_head; seg != NULL; seg = seg->right)
|
|
{
|
|
art_dprint (" %lx: (%g, %g)-(%g, %g), (a, b, c) = (%g, %g, %g)\n",
|
|
(unsigned long)seg,
|
|
seg->x[0], seg->y0, seg->x[1], seg->y1,
|
|
seg->a, seg->b, seg->c);
|
|
}
|
|
}
|
|
#endif
|
|
|
|
#ifdef SANITYCHECK
|
|
static void
|
|
art_svp_intersect_sanitycheck (ArtIntersectCtx *ctx)
|
|
{
|
|
ArtActiveSeg *seg;
|
|
ArtActiveSeg *last = NULL;
|
|
double d;
|
|
|
|
for (seg = ctx->active_head; seg != NULL; seg = seg->right)
|
|
{
|
|
if (seg->left != last)
|
|
{
|
|
art_warn ("*** art_svp_intersect_sanitycheck: last=%lx, seg->left=%lx\n",
|
|
(unsigned long)last, (unsigned long)seg->left);
|
|
}
|
|
if (last != NULL)
|
|
{
|
|
/* pairwise compare with previous seg */
|
|
|
|
/* First the top. */
|
|
if (last->y0 < seg->y0)
|
|
{
|
|
}
|
|
else
|
|
{
|
|
}
|
|
|
|
/* Then the bottom. */
|
|
if (last->y1 < seg->y1)
|
|
{
|
|
if (!((last->x[1] <
|
|
seg->x[(seg->flags & ART_ACTIVE_FLAGS_BNEG) ^ 1]) ||
|
|
last->y1 == seg->y0))
|
|
{
|
|
d = last->x[1] * seg->a + last->y1 * seg->b + seg->c;
|
|
if (d >= -EPSILON_A)
|
|
art_warn ("*** bottom (%g, %g) of %lx is not clear of %lx to right (d = %g)\n",
|
|
last->x[1], last->y1, (unsigned long) last,
|
|
(unsigned long) seg, d);
|
|
}
|
|
}
|
|
else if (last->y1 > seg->y1)
|
|
|
|
{
|
|
if (!((seg->x[1] >
|
|
last->x[last->flags & ART_ACTIVE_FLAGS_BNEG]) ||
|
|
seg->y1 == last->y0))
|
|
{
|
|
d = seg->x[1] * last->a + seg->y1 * last->b + last->c;
|
|
if (d <= EPSILON_A)
|
|
art_warn ("*** bottom (%g, %g) of %lx is not clear of %lx to left (d = %g)\n",
|
|
seg->x[1], seg->y1, (unsigned long) seg,
|
|
(unsigned long) last, d);
|
|
}
|
|
}
|
|
else
|
|
{
|
|
if (last->x[1] > seg->x[1])
|
|
art_warn ("*** bottoms (%g, %g) of %lx and (%g, %g) of %lx out of order\n",
|
|
last->x[1], last->y1, (unsigned long)last,
|
|
seg->x[1], seg->y1, (unsigned long)seg);
|
|
}
|
|
}
|
|
last = seg;
|
|
}
|
|
}
|
|
#endif
|
|
|
|
void
|
|
art_svp_intersector (const ArtSVP *in, ArtSvpWriter *out)
|
|
{
|
|
ArtIntersectCtx *ctx;
|
|
ArtPriQ *pq;
|
|
ArtPriPoint *first_point;
|
|
#ifdef VERBOSE
|
|
int count = 0;
|
|
#endif
|
|
|
|
if (in->n_segs == 0)
|
|
return;
|
|
|
|
ctx = art_new (ArtIntersectCtx, 1);
|
|
ctx->in = in;
|
|
ctx->out = out;
|
|
pq = art_pri_new ();
|
|
ctx->pq = pq;
|
|
|
|
ctx->active_head = NULL;
|
|
|
|
ctx->horiz_first = NULL;
|
|
ctx->horiz_last = NULL;
|
|
|
|
ctx->in_curs = 0;
|
|
first_point = art_new (ArtPriPoint, 1);
|
|
first_point->x = in->segs[0].points[0].x;
|
|
first_point->y = in->segs[0].points[0].y;
|
|
first_point->user_data = NULL;
|
|
ctx->y = first_point->y;
|
|
art_pri_insert (pq, first_point);
|
|
|
|
while (!art_pri_empty (pq))
|
|
{
|
|
ArtPriPoint *pri_point = art_pri_choose (pq);
|
|
ArtActiveSeg *seg = (ArtActiveSeg *)pri_point->user_data;
|
|
|
|
#ifdef VERBOSE
|
|
art_dprint ("\nIntersector step %d\n", count++);
|
|
art_svp_intersect_print_active (ctx);
|
|
art_dprint ("priq choose (%g, %g) %lx\n", pri_point->x, pri_point->y,
|
|
(unsigned long)pri_point->user_data);
|
|
#endif
|
|
#ifdef SANITYCHECK
|
|
art_svp_intersect_sanitycheck(ctx);
|
|
#endif
|
|
|
|
if (ctx->y != pri_point->y)
|
|
{
|
|
art_svp_intersect_horiz_commit (ctx);
|
|
ctx->y = pri_point->y;
|
|
}
|
|
|
|
if (seg == NULL)
|
|
{
|
|
/* Insert new segment from input */
|
|
const ArtSVPSeg *in_seg = &in->segs[ctx->in_curs++];
|
|
art_svp_intersect_add_seg (ctx, in_seg);
|
|
if (ctx->in_curs < in->n_segs)
|
|
{
|
|
const ArtSVPSeg *next_seg = &in->segs[ctx->in_curs];
|
|
pri_point->x = next_seg->points[0].x;
|
|
pri_point->y = next_seg->points[0].y;
|
|
/* user_data is already NULL */
|
|
art_pri_insert (pq, pri_point);
|
|
}
|
|
else
|
|
art_free (pri_point);
|
|
}
|
|
else
|
|
{
|
|
int n_stack = seg->n_stack;
|
|
|
|
if (n_stack > 1)
|
|
{
|
|
art_svp_intersect_process_intersection (ctx, seg);
|
|
art_free (pri_point);
|
|
}
|
|
else
|
|
{
|
|
art_svp_intersect_advance_cursor (ctx, seg, pri_point);
|
|
}
|
|
}
|
|
}
|
|
|
|
art_svp_intersect_horiz_commit (ctx);
|
|
|
|
art_pri_free (pq);
|
|
art_free (ctx);
|
|
}
|
|
|
|
#endif /* not TEST_PRIQ */
|