/* Libart_LGPL - library of basic graphic primitives
 * Copyright (C) 1998 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.
 */

#define noVERBOSE

/* Vector path set operations, over sorted vpaths. */

#include "art_misc.h"

#include "art_svp.h"
#include "art_vpath.h"
#include "art_svp_vpath.h"
#include "art_svp_wind.h"
#include "art_svp_ops.h"
#include "art_vpath_svp.h"

/* Merge the segments of the two svp's. The resulting svp will share
   segments with args passed in, so be super-careful with the
   allocation.  */

static ArtSVP *
art_svp_merge (const ArtSVP *svp1, const ArtSVP *svp2)
{
  ArtSVP *svp_new;
  int ix;
  int ix1, ix2;

  svp_new = (ArtSVP *)art_alloc (sizeof(ArtSVP) +
				 (svp1->n_segs + svp2->n_segs - 1) *
				 sizeof(ArtSVPSeg));
  ix1 = 0;
  ix2 = 0;
  for (ix = 0; ix < svp1->n_segs + svp2->n_segs; ix++)
    {
      if (ix1 < svp1->n_segs &&
	  (ix2 == svp2->n_segs ||
	   art_svp_seg_compare (&svp1->segs[ix1], &svp2->segs[ix2]) < 1))
	svp_new->segs[ix] = svp1->segs[ix1++];
      else
	svp_new->segs[ix] = svp2->segs[ix2++];
    }

  svp_new->n_segs = ix;
  return svp_new;
}

#ifdef VERBOSE

#define XOFF 50
#define YOFF 700

static void
print_ps_vpath (ArtVpath *vpath)
{
  int i;

  for (i = 0; vpath[i].code != ART_END; i++)
    {
      switch (vpath[i].code)
	{
	case ART_MOVETO:
	  printf ("%g %g moveto\n", XOFF + vpath[i].x, YOFF - vpath[i].y);
	  break;
	case ART_LINETO:
	  printf ("%g %g lineto\n", XOFF + vpath[i].x, YOFF - vpath[i].y);
	  break;
	default:
	  break;
	}
    }
  printf ("stroke showpage\n");
}

#define DELT 4

static void
print_ps_svp (ArtSVP *vpath)
{
  int i, j;

  printf ("%% begin\n");
  for (i = 0; i < vpath->n_segs; i++)
    {
      printf ("%g setgray\n", vpath->segs[i].dir ? 0.7 : 0);
      for (j = 0; j < vpath->segs[i].n_points; j++)
	{
	  printf ("%g %g %s\n",
		  XOFF + vpath->segs[i].points[j].x,
		  YOFF - vpath->segs[i].points[j].y,
		  j ? "lineto" : "moveto");
	}
      printf ("%g %g moveto %g %g lineto %g %g lineto %g %g lineto stroke\n",
	      XOFF + vpath->segs[i].points[0].x - DELT,
	      YOFF - DELT - vpath->segs[i].points[0].y,
	      XOFF + vpath->segs[i].points[0].x - DELT,
	      YOFF - vpath->segs[i].points[0].y,
	      XOFF + vpath->segs[i].points[0].x + DELT,
	      YOFF - vpath->segs[i].points[0].y,
	      XOFF + vpath->segs[i].points[0].x + DELT,
	      YOFF - DELT - vpath->segs[i].points[0].y);
      printf ("%g %g moveto %g %g lineto %g %g lineto %g %g lineto stroke\n",
	      XOFF + vpath->segs[i].points[j - 1].x - DELT,
	      YOFF + DELT - vpath->segs[i].points[j - 1].y,
	      XOFF + vpath->segs[i].points[j - 1].x - DELT,
	      YOFF - vpath->segs[i].points[j - 1].y,
	      XOFF + vpath->segs[i].points[j - 1].x + DELT,
	      YOFF - vpath->segs[i].points[j - 1].y,
	      XOFF + vpath->segs[i].points[j - 1].x + DELT,
	      YOFF + DELT - vpath->segs[i].points[j - 1].y);
      printf ("stroke\n");
    }

  printf ("showpage\n");
}
#endif

static ArtSVP *
art_svp_merge_perturbed (const ArtSVP *svp1, const ArtSVP *svp2)
{
  ArtVpath *vpath1, *vpath2;
  ArtVpath *vpath1_p, *vpath2_p;
  ArtSVP *svp1_p, *svp2_p;
  ArtSVP *svp_new;

  vpath1 = art_vpath_from_svp (svp1);
  vpath1_p = art_vpath_perturb (vpath1);
  art_free (vpath1);
  svp1_p = art_svp_from_vpath (vpath1_p);
  art_free (vpath1_p);

  vpath2 = art_vpath_from_svp (svp2);
  vpath2_p = art_vpath_perturb (vpath2);
  art_free (vpath2);
  svp2_p = art_svp_from_vpath (vpath2_p);
  art_free (vpath2_p);

  svp_new = art_svp_merge (svp1_p, svp2_p);
#ifdef VERBOSE
  print_ps_svp (svp1_p);
  print_ps_svp (svp2_p);
  print_ps_svp (svp_new);
#endif
  art_free (svp1_p);
  art_free (svp2_p);

  return svp_new;
}

/* Compute the union of two vector paths.

   Status of this routine:

   Basic correctness: Seems to work.

   Numerical stability: We cheat (adding random perturbation). Thus,
   it seems very likely that no numerical stability problems will be
   seen in practice.

   Speed: Would be better if we didn't go to unsorted vector path
   and back to add the perturbation.

   Precision: The perturbation fuzzes the coordinates slightly. In
   cases of butting segments, razor thin long holes may appear.

*/

ArtSVP *
art_svp_union (const ArtSVP *svp1, const ArtSVP *svp2)
{
  ArtSVP *svp3, *svp4, *svp_new;

  svp3 = art_svp_merge_perturbed (svp1, svp2);
  svp4 = art_svp_uncross (svp3);
  art_svp_free (svp3);

  svp_new = art_svp_rewind_uncrossed (svp4, ART_WIND_RULE_POSITIVE);
#ifdef VERBOSE
  print_ps_svp (svp4);
  print_ps_svp (svp_new);
#endif
  art_svp_free (svp4);
  return svp_new;
}

/* Compute the intersection of two vector paths.

   Status of this routine:

   Basic correctness: Seems to work.

   Numerical stability: We cheat (adding random perturbation). Thus,
   it seems very likely that no numerical stability problems will be
   seen in practice.

   Speed: Would be better if we didn't go to unsorted vector path
   and back to add the perturbation.

   Precision: The perturbation fuzzes the coordinates slightly. In
   cases of butting segments, razor thin long isolated segments may
   appear.

*/

ArtSVP *
art_svp_intersect (const ArtSVP *svp1, const ArtSVP *svp2)
{
  ArtSVP *svp3, *svp4, *svp_new;

  svp3 = art_svp_merge_perturbed (svp1, svp2);
  svp4 = art_svp_uncross (svp3);
  art_svp_free (svp3);

  svp_new = art_svp_rewind_uncrossed (svp4, ART_WIND_RULE_INTERSECT);
  art_svp_free (svp4);
  return svp_new;
}

/* Compute the symmetric difference of two vector paths.

   Status of this routine:

   Basic correctness: Seems to work.

   Numerical stability: We cheat (adding random perturbation). Thus,
   it seems very likely that no numerical stability problems will be
   seen in practice.

   Speed: We could do a lot better by scanning through the svp
   representations and culling out any segments that are exactly
   identical. It would also be better if we didn't go to unsorted
   vector path and back to add the perturbation.

   Precision: Awful. In the case of inputs which are similar (the
   common case for canvas display), the entire outline is "hairy." In
   addition, the perturbation fuzzes the coordinates slightly. It can
   be used as a conservative approximation.

*/

ArtSVP *
art_svp_diff (const ArtSVP *svp1, const ArtSVP *svp2)
{
  ArtSVP *svp3, *svp4, *svp_new;

  svp3 = art_svp_merge_perturbed (svp1, svp2);
  svp4 = art_svp_uncross (svp3);
  art_svp_free (svp3);

  svp_new = art_svp_rewind_uncrossed (svp4, ART_WIND_RULE_ODDEVEN);
  art_svp_free (svp4);
  return svp_new;
}