sweep.h

Mesa is an open-source implementation of the OpenGL specification - a system for rendering interacti

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/*
** Author: Eric Veach, July 1994.
**
** $Date: 2001/03/17 00:25:41 $ $Revision: 1.1 $
** $Header: /home/krh/git/sync/mesa-cvs-repo/Mesa/src/glu/sgi/libtess/sweep.h,v 1.1 2001/03/17 00:25:41 brianp Exp $
*/

#ifndef __sweep_h_
#define __sweep_h_

#include "mesh.h"

/* __gl_computeInterior( tess ) computes the planar arrangement specified
 * by the given contours, and further subdivides this arrangement
 * into regions.  Each region is marked "inside" if it belongs
 * to the polygon, according to the rule given by tess->windingRule.
 * Each interior region is guaranteed be monotone.
 */
int __gl_computeInterior( GLUtesselator *tess );


/* The following is here *only* for access by debugging routines */

#include "dict.h"

/* For each pair of adjacent edges crossing the sweep line, there is
 * an ActiveRegion to represent the region between them.  The active
 * regions are kept in sorted order in a dynamic dictionary.  As the
 * sweep line crosses each vertex, we update the affected regions.
 */

struct ActiveRegion {
  GLUhalfEdge	*eUp;		/* upper edge, directed right to left */
  DictNode	*nodeUp;	/* dictionary node corresponding to eUp */
  int		windingNumber;	/* used to determine which regions are
                                 * inside the polygon */
  GLboolean	inside;		/* is this region inside the polygon? */
  GLboolean	sentinel;	/* marks fake edges at t = +/-infinity */
  GLboolean	dirty;		/* marks regions where the upper or lower
                                 * edge has changed, but we haven't checked
                                 * whether they intersect yet */
  GLboolean	fixUpperEdge;	/* marks temporary edges introduced when
                                 * we process a "right vertex" (one without
                                 * any edges leaving to the right) */
};

#define RegionBelow(r)	((ActiveRegion *) dictKey(dictPred((r)->nodeUp)))
#define RegionAbove(r)	((ActiveRegion *) dictKey(dictSucc((r)->nodeUp)))

#endif