Source/sweep.h

/*
** SGI FREE SOFTWARE LICENSE B (Version 2.0, Sept. 18, 2008) 
** Copyright (C) [dates of first publication] Silicon Graphics, Inc.
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** 
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** included in all copies or substantial portions of the Software. 
**
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*/
/*
** Author: Eric Veach, July 1994.
*/

#ifndef SWEEP_H
#define SWEEP_H

#include "mesh.h"

/* tessComputeInterior( 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 tessComputeInterior( TESStesselator *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 {
	TESShalfEdge *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 */
	int inside;		/* is this region inside the polygon? */
	int sentinel;	/* marks fake edges at t = +/-infinity */
	int dirty;		/* marks regions where the upper or lower
					* edge has changed, but we haven't checked
					* whether they intersect yet */
	int 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