sweep File Reference

#include "mesh"
#include "dict"
#include "geom"
#include "_tess"
#include "priorityq"

Include dependency graph for sweep:

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Go to the source code of this file.

Classes
struct	ActiveRegion

Macros
#define	tools_glutess_sweep
#define	RegionBelow(r)   ((ActiveRegion *) dictKey(dictPred((r)->nodeUp)))
#define	RegionAbove(r)   ((ActiveRegion *) dictKey(dictSucc((r)->nodeUp)))
#define	DebugEvent(tess)
	inlined C code : /////////////////////////////////// More...
#define	AddWinding(eDst, eSrc)

Functions
inline void	static_SweepEvent (GLUtesselator *tess, GLUvertex *vEvent)
inline void	static_WalkDirtyRegions (GLUtesselator *tess, ActiveRegion *regUp)
inline int	static_CheckForRightSplice (GLUtesselator *tess, ActiveRegion *regUp)
inline int	static_EdgeLeq (GLUtesselator *tess, ActiveRegion *reg1, ActiveRegion *reg2)
inline void	static_DeleteRegion (GLUtesselator *tess, ActiveRegion *reg)
inline int	static_FixUpperEdge (ActiveRegion *reg, GLUhalfEdge *newEdge)
inline ActiveRegion *	static_TopLeftRegion (ActiveRegion *reg)
inline ActiveRegion *	static_TopRightRegion (ActiveRegion *reg)
inline ActiveRegion *	static_AddRegionBelow (GLUtesselator *tess, ActiveRegion *regAbove, GLUhalfEdge *eNewUp)
inline GLUboolean	static_IsWindingInside (GLUtesselator *tess, int n)
inline void	static_ComputeWinding (GLUtesselator *tess, ActiveRegion *reg)
inline void	static_FinishRegion (GLUtesselator *tess, ActiveRegion *reg)
inline GLUhalfEdge *	static_FinishLeftRegions (GLUtesselator *tess, ActiveRegion *regFirst, ActiveRegion *regLast)
inline void	static_AddRightEdges (GLUtesselator *tess, ActiveRegion *regUp, GLUhalfEdge *eFirst, GLUhalfEdge *eLast, GLUhalfEdge *eTopLeft, GLUboolean cleanUp)
inline void	static_CallCombine (GLUtesselator *tess, GLUvertex *isect, void *data[4], GLUfloat weights[4], int needed)
inline void	static_SpliceMergeVertices (GLUtesselator *tess, GLUhalfEdge *e1, GLUhalfEdge *e2)
inline void	static_VertexWeights (GLUvertex *isect, GLUvertex *org, GLUvertex *dst, GLUfloat *weights)
inline void	static_GetIntersectData (GLUtesselator *tess, GLUvertex *isect, GLUvertex *orgUp, GLUvertex *dstUp, GLUvertex *orgLo, GLUvertex *dstLo)
inline int	static_CheckForLeftSplice (GLUtesselator *tess, ActiveRegion *regUp)
inline int	static_CheckForIntersect (GLUtesselator *tess, ActiveRegion *regUp)
inline void	static_ConnectRightVertex (GLUtesselator *tess, ActiveRegion *regUp, GLUhalfEdge *eBottomLeft)
inline void	static_ConnectLeftDegenerate (GLUtesselator *tess, ActiveRegion *regUp, GLUvertex *vEvent)
inline void	static_ConnectLeftVertex (GLUtesselator *tess, GLUvertex *vEvent)
GLUdouble	SENTINEL_COORD ()
inline void	static_AddSentinel (GLUtesselator *tess, GLUdouble t)
inline void	static_InitEdgeDict (GLUtesselator *tess)
inline void	static_DoneEdgeDict (GLUtesselator *tess)
inline void	static_RemoveDegenerateEdges (GLUtesselator *tess)
inline int	static_InitPriorityQ (GLUtesselator *tess)
inline void	static_DonePriorityQ (GLUtesselator *tess)
inline int	static_RemoveDegenerateFaces (GLUmesh *mesh)
int	__gl_computeInterior (GLUtesselator *tess)

Macro Definition Documentation

AddWinding

#define AddWinding	(		eDst,
			eSrc
	)

Value:

                                 (eDst->winding += eSrc->winding, \
                                 eDst->Sym->winding += eSrc->Sym->winding)

Definition at line 76 of file sweep.

DebugEvent

#define DebugEvent

(

tess

)

inlined C code : ///////////////////////////////////

Definition at line 41 of file sweep.

RegionAbove

#define RegionAbove

(

r

)

((ActiveRegion *) dictKey(dictSucc((r)->nodeUp)))

Definition at line 31 of file sweep.

RegionBelow

#define RegionBelow

(

r

)

((ActiveRegion *) dictKey(dictPred((r)->nodeUp)))

Definition at line 30 of file sweep.

tools_glutess_sweep

#define tools_glutess_sweep

Definition at line 4 of file sweep.

Function Documentation

__gl_computeInterior()

int __gl_computeInterior ( GLUtesselator *  tess )

inline

Definition at line 1287 of file sweep.

{
  GLUvertex *v, *vNext;
 
  tess->fatalError = TOOLS_GLU_FALSE;
 
  /* Each vertex defines an event for our sweep line.  Start by inserting
   * all the vertices in a priority queue.  Events are processed in
   * lexicographic order, ie.
   *
   *    e1 < e2  iff  e1.x < e2.x || (e1.x == e2.x && e1.y < e2.y)
   */
  static_RemoveDegenerateEdges( tess );
  if ( !static_InitPriorityQ( tess ) ) return 0; /* if error */
  static_InitEdgeDict( tess );
 
  /* __gl_pqSortExtractMin */
  while( (v = (GLUvertex *)pqExtractMin( tess->pq )) != NULL ) {
    for( ;; ) {
      vNext = (GLUvertex *)pqMinimum( tess->pq ); /* __gl_pqSortMinimum */
      if( vNext == NULL || ! VertEq( vNext, v )) break;
 
      /* Merge together all vertices at exactly the same location.
       * This is more efficient than processing them one at a time,
       * simplifies the code (see ConnectLeftDegenerate), and is also
       * important for correct handling of certain degenerate cases.
       * For example, suppose there are two identical edges A and B
       * that belong to different contours (so without this code they would
       * be processed by separate sweep events).  Suppose another edge C
       * crosses A and B from above.  When A is processed, we split it
       * at its intersection point with C.  However this also splits C,
       * so when we insert B we may compute a slightly different
       * intersection point.  This might leave two edges with a small
       * gap between them.  This kind of error is especially obvious
       * when using boundary extraction (GLU_TESS_BOUNDARY_ONLY).
       */
      vNext = (GLUvertex *)pqExtractMin( tess->pq ); /* __gl_pqSortExtractMin*/
      static_SpliceMergeVertices( tess, v->anEdge, vNext->anEdge );
    }
    static_SweepEvent( tess, v );
  }
 
  /* Set tess->event for debugging purposes */
  /* __GL_DICTLISTKEY */ /* __GL_DICTLISTMIN */
  tess->event = ((ActiveRegion *) dictKey( dictMin( tess->dict )))->eUp->Org;
  DebugEvent( tess );
  static_DoneEdgeDict( tess );
  static_DonePriorityQ( tess );
 
  if ( !static_RemoveDegenerateFaces( tess->mesh ) ) return 0;
  __gl_meshCheckMesh( tess->mesh );
 
  return 1;
}

SENTINEL_COORD()

GLUdouble SENTINEL_COORD ( )

inline

Definition at line 1103 of file sweep.

                                  {
  static const GLUdouble s_value = 4 * GLU_TESS_MAX_COORD;
  return s_value;
}

static_AddRegionBelow()

inline ActiveRegion* static_AddRegionBelow	(	GLUtesselator *	tess,
		ActiveRegion *	regAbove,
		GLUhalfEdge *	eNewUp
	)

Definition at line 189 of file sweep.

{
  ActiveRegion *regNew = (ActiveRegion *)memAlloc( sizeof( ActiveRegion ));
  if (regNew == NULL) longjmp(tess->env,1);
 
  regNew->eUp = eNewUp;
  /* __gl_dictListInsertBefore */
  regNew->nodeUp = dictInsertBefore( tess->dict, regAbove->nodeUp, regNew );
  if (regNew->nodeUp == NULL) longjmp(tess->env,1);
  regNew->fixUpperEdge = TOOLS_GLU_FALSE;
  regNew->sentinel = TOOLS_GLU_FALSE;
  regNew->dirty = TOOLS_GLU_FALSE;
 
  eNewUp->activeRegion = regNew;
  return regNew;
}

static_AddRightEdges()

inline void static_AddRightEdges	(	GLUtesselator *	tess,
		ActiveRegion *	regUp,
		GLUhalfEdge *	eFirst,
		GLUhalfEdge *	eLast,
		GLUhalfEdge *	eTopLeft,
		GLUboolean	cleanUp
	)

Definition at line 316 of file sweep.

{
  ActiveRegion *reg, *regPrev;
  GLUhalfEdge *e, *ePrev;
  int firstTime = TOOLS_GLU_TRUE;
 
  /* Insert the new right-going edges in the dictionary */
  e = eFirst;
  do {
    assert( VertLeq( e->Org, e->Dst ));
    static_AddRegionBelow( tess, regUp, e->Sym );
    e = e->Onext;
  } while ( e != eLast );
 
  /* Walk *all* right-going edges from e->Org, in the dictionary order,
   * updating the winding numbers of each region, and re-linking the mesh
   * edges to match the dictionary ordering (if necessary).
   */
  if( eTopLeft == NULL ) {
    eTopLeft = RegionBelow( regUp )->eUp->Rprev;
  }
  regPrev = regUp;
  ePrev = eTopLeft;
  for( ;; ) {
    reg = RegionBelow( regPrev );
    e = reg->eUp->Sym;
    if( e->Org != ePrev->Org ) break;
 
    if( e->Onext != ePrev ) {
      /* Unlink e from its current position, and relink below ePrev */
      if ( !__gl_meshSplice( e->Oprev, e ) ) longjmp(tess->env,1);
      if ( !__gl_meshSplice( ePrev->Oprev, e ) ) longjmp(tess->env,1);
    }
    /* Compute the winding number and "inside" flag for the new regions */
    reg->windingNumber = regPrev->windingNumber - e->winding;
    reg->inside = static_IsWindingInside( tess, reg->windingNumber );
 
    /* Check for two outgoing edges with same slope -- process these
     * before any intersection tests (see example in __gl_computeInterior).
     */
    regPrev->dirty = TOOLS_GLU_TRUE;
    if( ! firstTime && static_CheckForRightSplice( tess, regPrev )) {
      AddWinding( e, ePrev );
      static_DeleteRegion( tess, regPrev );
      if ( !__gl_meshDelete( ePrev ) ) longjmp(tess->env,1);
    }
    firstTime = TOOLS_GLU_FALSE;
    regPrev = reg;
    ePrev = e;
  }
  regPrev->dirty = TOOLS_GLU_TRUE;
  assert( regPrev->windingNumber - e->winding == reg->windingNumber );
 
  if( cleanUp ) {
    /* Check for intersections between newly adjacent edges. */
    static_WalkDirtyRegions( tess, regPrev );
  }
}

static_AddSentinel()

inline void static_AddSentinel	(	GLUtesselator *	tess,
		GLUdouble	t
	)

Definition at line 1108 of file sweep.

{
  GLUhalfEdge *e;
  ActiveRegion *reg = (ActiveRegion *)memAlloc( sizeof( ActiveRegion ));
  if (reg == NULL) longjmp(tess->env,1);
 
  e = __gl_meshMakeEdge( tess->mesh );
  if (e == NULL) longjmp(tess->env,1);
 
  e->Org->s = SENTINEL_COORD();
  e->Org->t = t;
  e->Dst->s = -SENTINEL_COORD();
  e->Dst->t = t;
  tess->event = e->Dst;     /* initialize it */
 
  reg->eUp = e;
  reg->windingNumber = 0;
  reg->inside = TOOLS_GLU_FALSE;
  reg->fixUpperEdge = TOOLS_GLU_FALSE;
  reg->sentinel = TOOLS_GLU_TRUE;
  reg->dirty = TOOLS_GLU_FALSE;
  reg->nodeUp = dictInsert( tess->dict, reg ); /* __gl_dictListInsertBefore */
  if (reg->nodeUp == NULL) longjmp(tess->env,1);
}

static_CallCombine()

inline void static_CallCombine	(	GLUtesselator *	tess,
		GLUvertex *	isect,
		void *	data[4],
		GLUfloat	weights[4],
		int	needed
	)

Definition at line 388 of file sweep.

{
  GLUdouble coords[3];
 
  /* Copy coord data in case the callback changes it. */
  coords[0] = isect->coords[0];
  coords[1] = isect->coords[1];
  coords[2] = isect->coords[2];
 
  isect->data = NULL;
  CALL_COMBINE_OR_COMBINE_DATA( coords, data, weights, &isect->data );
  if( isect->data == NULL ) {
    if( ! needed ) {
      isect->data = data[0];
    } else if( ! tess->fatalError ) {
      /* The only way fatal error is when two edges are found to intersect,
       * but the user has not provided the callback necessary to handle
       * generated intersection points.
       */
      CALL_ERROR_OR_ERROR_DATA( GLU_TESS_NEED_COMBINE_CALLBACK );
      tess->fatalError = TOOLS_GLU_TRUE;
    }
  }
}

static_CheckForIntersect()

inline int static_CheckForIntersect	(	GLUtesselator *	tess,
		ActiveRegion *	regUp
	)

Definition at line 582 of file sweep.

{
  ActiveRegion *regLo = RegionBelow(regUp);
  GLUhalfEdge *eUp = regUp->eUp;
  GLUhalfEdge *eLo = regLo->eUp;
  GLUvertex *orgUp = eUp->Org;
  GLUvertex *orgLo = eLo->Org;
  GLUvertex *dstUp = eUp->Dst;
  GLUvertex *dstLo = eLo->Dst;
  GLUdouble tMinUp, tMaxLo;
  GLUvertex isect, *orgMin;
  GLUhalfEdge *e;
 
  assert( ! VertEq( dstLo, dstUp ));
  assert( EdgeSign( dstUp, tess->event, orgUp ) <= 0 );
  assert( EdgeSign( dstLo, tess->event, orgLo ) >= 0 );
  assert( orgUp != tess->event && orgLo != tess->event );
  assert( ! regUp->fixUpperEdge && ! regLo->fixUpperEdge );
 
  if( orgUp == orgLo ) return TOOLS_GLU_FALSE;  /* right endpoints are the same */
 
  tMinUp = GLU_MIN( orgUp->t, dstUp->t );
  tMaxLo = GLU_MAX( orgLo->t, dstLo->t );
  if( tMinUp > tMaxLo ) return TOOLS_GLU_FALSE; /* t ranges do not overlap */
 
  if( VertLeq( orgUp, orgLo )) {
    if( EdgeSign( dstLo, orgUp, orgLo ) > 0 ) return TOOLS_GLU_FALSE;
  } else {
    if( EdgeSign( dstUp, orgLo, orgUp ) < 0 ) return TOOLS_GLU_FALSE;
  }
 
  /* At this point the edges intersect, at least marginally */
  DebugEvent( tess );
 
  __gl_edgeIntersect( dstUp, orgUp, dstLo, orgLo, &isect );
  /* The following properties are guaranteed: */
  assert( GLU_MIN( orgUp->t, dstUp->t ) <= isect.t );
  assert( isect.t <= GLU_MAX( orgLo->t, dstLo->t ));
  assert( GLU_MIN( dstLo->s, dstUp->s ) <= isect.s );
  assert( isect.s <= GLU_MAX( orgLo->s, orgUp->s ));
 
  if( VertLeq( &isect, tess->event )) {
    /* The intersection point lies slightly to the left of the sweep line,
     * so move it until it''s slightly to the right of the sweep line.
     * (If we had perfect numerical precision, this would never happen
     * in the first place).  The easiest and safest thing to do is
     * replace the intersection by tess->event.
     */
    isect.s = tess->event->s;
    isect.t = tess->event->t;
  }
  /* Similarly, if the computed intersection lies to the right of the
   * rightmost origin (which should rarely happen), it can cause
   * unbelievable inefficiency on sufficiently degenerate inputs.
   * (If you have the test program, try running test54.d with the
   * "X zoom" option turned on).
   */
  orgMin = VertLeq( orgUp, orgLo ) ? orgUp : orgLo;
  if( VertLeq( orgMin, &isect )) {
    isect.s = orgMin->s;
    isect.t = orgMin->t;
  }
 
  if( VertEq( &isect, orgUp ) || VertEq( &isect, orgLo )) {
    /* Easy case -- intersection at one of the right endpoints */
    (void) static_CheckForRightSplice( tess, regUp );
    return TOOLS_GLU_FALSE;
  }
 
  if(    (! VertEq( dstUp, tess->event )
      && EdgeSign( dstUp, tess->event, &isect ) >= 0)
      || (! VertEq( dstLo, tess->event )
      && EdgeSign( dstLo, tess->event, &isect ) <= 0 ))
  {
    /* Very unusual -- the new upper or lower edge would pass on the
     * wrong side of the sweep event, or through it.  This can happen
     * due to very small numerical errors in the intersection calculation.
     */
    if( dstLo == tess->event ) {
      /* Splice dstLo into eUp, and process the new region(s) */
      if (__gl_meshSplitEdge( eUp->Sym ) == NULL) longjmp(tess->env,1);
      if ( !__gl_meshSplice( eLo->Sym, eUp ) ) longjmp(tess->env,1);
      regUp = static_TopLeftRegion( regUp );
      if (regUp == NULL) longjmp(tess->env,1);
      eUp = RegionBelow(regUp)->eUp;
      static_FinishLeftRegions( tess, RegionBelow(regUp), regLo );
      static_AddRightEdges( tess, regUp, eUp->Oprev, eUp, eUp, TOOLS_GLU_TRUE );
      return TOOLS_GLU_TRUE;
    }
    if( dstUp == tess->event ) {
      /* Splice dstUp into eLo, and process the new region(s) */
      if (__gl_meshSplitEdge( eLo->Sym ) == NULL) longjmp(tess->env,1);
      if ( !__gl_meshSplice( eUp->Lnext, eLo->Oprev ) ) longjmp(tess->env,1);
      regLo = regUp;
      regUp = static_TopRightRegion( regUp );
      e = RegionBelow(regUp)->eUp->Rprev;
      regLo->eUp = eLo->Oprev;
      eLo = static_FinishLeftRegions( tess, regLo, NULL );
      static_AddRightEdges( tess, regUp, eLo->Onext, eUp->Rprev, e, TOOLS_GLU_TRUE );
      return TOOLS_GLU_TRUE;
    }
    /* Special case: called from ConnectRightVertex.  If either
     * edge passes on the wrong side of tess->event, split it
     * (and wait for ConnectRightVertex to splice it appropriately).
     */
    if( EdgeSign( dstUp, tess->event, &isect ) >= 0 ) {
      RegionAbove(regUp)->dirty = regUp->dirty = TOOLS_GLU_TRUE;
      if (__gl_meshSplitEdge( eUp->Sym ) == NULL) longjmp(tess->env,1);
      eUp->Org->s = tess->event->s;
      eUp->Org->t = tess->event->t;
    }
    if( EdgeSign( dstLo, tess->event, &isect ) <= 0 ) {
      regUp->dirty = regLo->dirty = TOOLS_GLU_TRUE;
      if (__gl_meshSplitEdge( eLo->Sym ) == NULL) longjmp(tess->env,1);
      eLo->Org->s = tess->event->s;
      eLo->Org->t = tess->event->t;
    }
    /* leave the rest for ConnectRightVertex */
    return TOOLS_GLU_FALSE;
  }
 
  /* General case -- split both edges, splice into new vertex.
   * When we do the splice operation, the order of the arguments is
   * arbitrary as far as correctness goes.  However, when the operation
   * creates a new face, the work done is proportional to the size of
   * the new face.  We expect the faces in the processed part of
   * the mesh (ie. eUp->Lface) to be smaller than the faces in the
   * unprocessed original contours (which will be eLo->Oprev->Lface).
   */
  if (__gl_meshSplitEdge( eUp->Sym ) == NULL) longjmp(tess->env,1);
  if (__gl_meshSplitEdge( eLo->Sym ) == NULL) longjmp(tess->env,1);
  if ( !__gl_meshSplice( eLo->Oprev, eUp ) ) longjmp(tess->env,1);
  eUp->Org->s = isect.s;
  eUp->Org->t = isect.t;
  eUp->Org->pqHandle = pqInsert( tess->pq, eUp->Org ); /* __gl_pqSortInsert */
  if (eUp->Org->pqHandle == LONG_MAX) {
     pqDeletePriorityQ(tess->pq);   /* __gl_pqSortDeletePriorityQ */
     tess->pq = NULL;
     longjmp(tess->env,1);
  }
  static_GetIntersectData( tess, eUp->Org, orgUp, dstUp, orgLo, dstLo );
  RegionAbove(regUp)->dirty = regUp->dirty = regLo->dirty = TOOLS_GLU_TRUE;
  return TOOLS_GLU_FALSE;
}

static_CheckForLeftSplice()

inline int static_CheckForLeftSplice	(	GLUtesselator *	tess,
		ActiveRegion *	regUp
	)

Definition at line 532 of file sweep.

{
  ActiveRegion *regLo = RegionBelow(regUp);
  GLUhalfEdge *eUp = regUp->eUp;
  GLUhalfEdge *eLo = regLo->eUp;
  GLUhalfEdge *e;
 
  assert( ! VertEq( eUp->Dst, eLo->Dst ));
 
  if( VertLeq( eUp->Dst, eLo->Dst )) {
    if( EdgeSign( eUp->Dst, eLo->Dst, eUp->Org ) < 0 ) return TOOLS_GLU_FALSE;
 
    /* eLo->Dst is above eUp, so splice eLo->Dst into eUp */
    RegionAbove(regUp)->dirty = regUp->dirty = TOOLS_GLU_TRUE;
    e = __gl_meshSplitEdge( eUp );
    if (e == NULL) longjmp(tess->env,1);
    if ( !__gl_meshSplice( eLo->Sym, e ) ) longjmp(tess->env,1);
    e->Lface->inside = regUp->inside;
  } else {
    if( EdgeSign( eLo->Dst, eUp->Dst, eLo->Org ) > 0 ) return TOOLS_GLU_FALSE;
 
    /* eUp->Dst is below eLo, so splice eUp->Dst into eLo */
    regUp->dirty = regLo->dirty = TOOLS_GLU_TRUE;
    e = __gl_meshSplitEdge( eLo );
    if (e == NULL) longjmp(tess->env,1);
    if ( !__gl_meshSplice( eUp->Lnext, eLo->Sym ) ) longjmp(tess->env,1);
    e->Rface->inside = regUp->inside;
  }
  return TOOLS_GLU_TRUE;
}

static_CheckForRightSplice()

int static_CheckForRightSplice	(	GLUtesselator *	tess,
		ActiveRegion *	regUp
	)

Definition at line 475 of file sweep.

{
  ActiveRegion *regLo = RegionBelow(regUp);
  GLUhalfEdge *eUp = regUp->eUp;
  GLUhalfEdge *eLo = regLo->eUp;
 
  if( VertLeq( eUp->Org, eLo->Org )) {
    if( EdgeSign( eLo->Dst, eUp->Org, eLo->Org ) > 0 ) return TOOLS_GLU_FALSE;
 
    /* eUp->Org appears to be below eLo */
    if( ! VertEq( eUp->Org, eLo->Org )) {
      /* Splice eUp->Org into eLo */
      if ( __gl_meshSplitEdge( eLo->Sym ) == NULL) longjmp(tess->env,1);
      if ( !__gl_meshSplice( eUp, eLo->Oprev ) ) longjmp(tess->env,1);
      regUp->dirty = regLo->dirty = TOOLS_GLU_TRUE;
 
    } else if( eUp->Org != eLo->Org ) {
      /* merge the two vertices, discarding eUp->Org */
      pqDelete( tess->pq, eUp->Org->pqHandle ); /* __gl_pqSortDelete */
      static_SpliceMergeVertices( tess, eLo->Oprev, eUp );
    }
  } else {
    if( EdgeSign( eUp->Dst, eLo->Org, eUp->Org ) < 0 ) return TOOLS_GLU_FALSE;
 
    /* eLo->Org appears to be above eUp, so splice eLo->Org into eUp */
    RegionAbove(regUp)->dirty = regUp->dirty = TOOLS_GLU_TRUE;
    if (__gl_meshSplitEdge( eUp->Sym ) == NULL) longjmp(tess->env,1);
    if ( !__gl_meshSplice( eLo->Oprev, eUp ) ) longjmp(tess->env,1);
  }
  return TOOLS_GLU_TRUE;
}

static_ComputeWinding()

inline void static_ComputeWinding	(	GLUtesselator *	tess,
		ActiveRegion *	reg
	)

Definition at line 235 of file sweep.

{
  reg->windingNumber = RegionAbove(reg)->windingNumber + reg->eUp->winding;
  reg->inside = static_IsWindingInside( tess, reg->windingNumber );
}

static_ConnectLeftDegenerate()

inline void static_ConnectLeftDegenerate	(	GLUtesselator *	tess,
		ActiveRegion *	regUp,
		GLUvertex *	vEvent
	)

Definition at line 917 of file sweep.

{
  GLUhalfEdge *e, *eTopLeft, *eTopRight, *eLast;
  ActiveRegion *reg;
 
  e = regUp->eUp;
  if( VertEq( e->Org, vEvent )) {
    /* e->Org is an unprocessed vertex - just combine them, and wait
     * for e->Org to be pulled from the queue
     */
    assert( /*TOLERANCE_NONZERO*/ TOOLS_GLU_FALSE );
    static_SpliceMergeVertices( tess, e, vEvent->anEdge );
    return;
  }
 
  if( ! VertEq( e->Dst, vEvent )) {
    /* General case -- splice vEvent into edge e which passes through it */
    if (__gl_meshSplitEdge( e->Sym ) == NULL) longjmp(tess->env,1);
    if( regUp->fixUpperEdge ) {
      /* This edge was fixable -- delete unused portion of original edge */
      if ( !__gl_meshDelete( e->Onext ) ) longjmp(tess->env,1);
      regUp->fixUpperEdge = TOOLS_GLU_FALSE;
    }
    if ( !__gl_meshSplice( vEvent->anEdge, e ) ) longjmp(tess->env,1);
    static_SweepEvent( tess, vEvent ); /* recurse */
    return;
  }
 
  /* vEvent coincides with e->Dst, which has already been processed.
   * Splice in the additional right-going edges.
   */
  assert( /*TOLERANCE_NONZERO*/ TOOLS_GLU_FALSE );
  regUp = static_TopRightRegion( regUp );
  reg = RegionBelow( regUp );
  eTopRight = reg->eUp->Sym;
  eTopLeft = eLast = eTopRight->Onext;
  if( reg->fixUpperEdge ) {
    /* Here e->Dst has only a single fixable edge going right.
     * We can delete it since now we have some real right-going edges.
     */
    assert( eTopLeft != eTopRight );   /* there are some left edges too */
    static_DeleteRegion( tess, reg );
    if ( !__gl_meshDelete( eTopRight ) ) longjmp(tess->env,1);
    eTopRight = eTopLeft->Oprev;
  }
  if ( !__gl_meshSplice( vEvent->anEdge, eTopRight ) ) longjmp(tess->env,1);
  if( ! EdgeGoesLeft( eTopLeft )) {
    /* e->Dst had no left-going edges -- indicate this to AddRightEdges() */
    eTopLeft = NULL;
  }
  static_AddRightEdges( tess, regUp, eTopRight->Onext, eLast, eTopLeft, TOOLS_GLU_TRUE );
}

static_ConnectLeftVertex()

inline void static_ConnectLeftVertex	(	GLUtesselator *	tess,
		GLUvertex *	vEvent
	)

Definition at line 977 of file sweep.

{
  ActiveRegion *regUp, *regLo, *reg;
  GLUhalfEdge *eUp, *eLo, *eNew;
  ActiveRegion tmp;
 
  /* assert( vEvent->anEdge->Onext->Onext == vEvent->anEdge ); */
 
  /* Get a pointer to the active region containing vEvent */
  tmp.eUp = vEvent->anEdge->Sym;
  /* __GL_DICTLISTKEY */ /* __gl_dictListSearch */
  regUp = (ActiveRegion *)dictKey( dictSearch( tess->dict, &tmp ));
  regLo = RegionBelow( regUp );
  eUp = regUp->eUp;
  eLo = regLo->eUp;
 
  /* Try merging with U or L first */
  if( EdgeSign( eUp->Dst, vEvent, eUp->Org ) == 0 ) {
    static_ConnectLeftDegenerate( tess, regUp, vEvent );
    return;
  }
 
  /* Connect vEvent to rightmost processed vertex of either chain.
   * e->Dst is the vertex that we will connect to vEvent.
   */
  reg = VertLeq( eLo->Dst, eUp->Dst ) ? regUp : regLo;
 
  if( regUp->inside || reg->fixUpperEdge) {
    if( reg == regUp ) {
      eNew = __gl_meshConnect( vEvent->anEdge->Sym, eUp->Lnext );
      if (eNew == NULL) longjmp(tess->env,1);
    } else {
      GLUhalfEdge *tempHalfEdge= __gl_meshConnect( eLo->Dnext, vEvent->anEdge);
      if (tempHalfEdge == NULL) longjmp(tess->env,1);
 
      eNew = tempHalfEdge->Sym;
    }
    if( reg->fixUpperEdge ) {
      if ( !static_FixUpperEdge( reg, eNew ) ) longjmp(tess->env,1);
    } else {
      static_ComputeWinding( tess, static_AddRegionBelow( tess, regUp, eNew ));
    }
    static_SweepEvent( tess, vEvent );
  } else {
    /* The new vertex is in a region which does not belong to the polygon.
     * We don''t need to connect this vertex to the rest of the mesh.
     */
    static_AddRightEdges( tess, regUp, vEvent->anEdge, vEvent->anEdge, NULL, TOOLS_GLU_TRUE );
  }
}

static_ConnectRightVertex()

inline void static_ConnectRightVertex	(	GLUtesselator *	tess,
		ActiveRegion *	regUp,
		GLUhalfEdge *	eBottomLeft
	)

Definition at line 823 of file sweep.

{
  GLUhalfEdge *eNew;
  GLUhalfEdge *eTopLeft = eBottomLeft->Onext;
  ActiveRegion *regLo = RegionBelow(regUp);
  GLUhalfEdge *eUp = regUp->eUp;
  GLUhalfEdge *eLo = regLo->eUp;
  int degenerate = TOOLS_GLU_FALSE;
 
  if( eUp->Dst != eLo->Dst ) {
    (void) static_CheckForIntersect( tess, regUp );
  }
 
  /* Possible new degeneracies: upper or lower edge of regUp may pass
   * through vEvent, or may coincide with new intersection vertex
   */
  if( VertEq( eUp->Org, tess->event )) {
    if ( !__gl_meshSplice( eTopLeft->Oprev, eUp ) ) longjmp(tess->env,1);
    regUp = static_TopLeftRegion( regUp );
    if (regUp == NULL) longjmp(tess->env,1);
    eTopLeft = RegionBelow( regUp )->eUp;
    static_FinishLeftRegions( tess, RegionBelow(regUp), regLo );
    degenerate = TOOLS_GLU_TRUE;
  }
  if( VertEq( eLo->Org, tess->event )) {
    if ( !__gl_meshSplice( eBottomLeft, eLo->Oprev ) ) longjmp(tess->env,1);
    eBottomLeft = static_FinishLeftRegions( tess, regLo, NULL );
    degenerate = TOOLS_GLU_TRUE;
  }
  if( degenerate ) {
    static_AddRightEdges( tess, regUp, eBottomLeft->Onext, eTopLeft, eTopLeft, TOOLS_GLU_TRUE );
    return;
  }
 
  /* Non-degenerate situation -- need to add a temporary, fixable edge.
   * Connect to the closer of eLo->Org, eUp->Org.
   */
  if( VertLeq( eLo->Org, eUp->Org )) {
    eNew = eLo->Oprev;
  } else {
    eNew = eUp;
  }
  eNew = __gl_meshConnect( eBottomLeft->Lprev, eNew );
  if (eNew == NULL) longjmp(tess->env,1);
 
  /* Prevent cleanup, otherwise eNew might disappear before we've even
   * had a chance to mark it as a temporary edge.
   */
  static_AddRightEdges( tess, regUp, eNew, eNew->Onext, eNew->Onext, TOOLS_GLU_FALSE );
  eNew->Sym->activeRegion->fixUpperEdge = TOOLS_GLU_TRUE;
  static_WalkDirtyRegions( tess, regUp );
}

static_DeleteRegion()

inline void static_DeleteRegion	(	GLUtesselator *	tess,
		ActiveRegion *	reg
	)

Definition at line 127 of file sweep.

{
  if( reg->fixUpperEdge ) {
    /* It was created with zero winding number, so it better be
     * deleted with zero winding number (ie. it better not get merged
     * with a real edge).
     */
    assert( reg->eUp->winding == 0 );
  }
  reg->eUp->activeRegion = NULL;
  dictDelete( tess->dict, reg->nodeUp ); /* __gl_dictListDelete */
  memFree( reg );
}

static_DoneEdgeDict()

inline void static_DoneEdgeDict

(

GLUtesselator *

tess

)

Definition at line 1153 of file sweep.

{
  ActiveRegion *reg;
#ifndef NDEBUG
  int fixedEdges = 0;
#endif
 
  /* __GL_DICTLISTKEY */ /* __GL_DICTLISTMIN */
  while( (reg = (ActiveRegion *)dictKey( dictMin( tess->dict ))) != NULL ) {
    /*
     * At the end of all processing, the dictionary should contain
     * only the two sentinel edges, plus at most one "fixable" edge
     * created by ConnectRightVertex().
     */
    if( ! reg->sentinel ) {
      assert( reg->fixUpperEdge );
    //G.Barrand : fix a Coverity diagnostic : begin :
    //assert( ++fixedEdges == 1 );
#ifndef NDEBUG
      fixedEdges++;
#endif
      assert( fixedEdges == 1 );
    //G.Barrand : end.
    }
    assert( reg->windingNumber == 0 );
    static_DeleteRegion( tess, reg );
/*    __gl_meshDelete( reg->eUp );*/
  }
  dictDeleteDict( tess->dict ); /* __gl_dictListDeleteDict */
}

static_DonePriorityQ()

inline void static_DonePriorityQ

(

GLUtesselator *

tess

)

Definition at line 1247 of file sweep.

{
  pqDeletePriorityQ( tess->pq ); /* __gl_pqSortDeletePriorityQ */
}

static_EdgeLeq()

inline int static_EdgeLeq	(	GLUtesselator *	tess,
		ActiveRegion *	reg1,
		ActiveRegion *	reg2
	)

Definition at line 83 of file sweep.

{
  GLUvertex *event = tess->event;
  GLUhalfEdge *e1, *e2;
  GLUdouble t1, t2;
 
  e1 = reg1->eUp;
  e2 = reg2->eUp;
 
  if( e1->Dst == event ) {
    if( e2->Dst == event ) {
      /* Two edges right of the sweep line which meet at the sweep event.
       * Sort them by slope.
       */
      if( VertLeq( e1->Org, e2->Org )) {
    return EdgeSign( e2->Dst, e1->Org, e2->Org ) <= 0;
      }
      return EdgeSign( e1->Dst, e2->Org, e1->Org ) >= 0;
    }
    return EdgeSign( e2->Dst, event, e2->Org ) <= 0;
  }
  if( e2->Dst == event ) {
    return EdgeSign( e1->Dst, event, e1->Org ) >= 0;
  }
 
  /* General case - compute signed distance *from* e1, e2 to event */
  t1 = EdgeEval( e1->Dst, event, e1->Org );
  t2 = EdgeEval( e2->Dst, event, e2->Org );
  return (t1 >= t2);
}

static_FinishLeftRegions()

inline GLUhalfEdge* static_FinishLeftRegions	(	GLUtesselator *	tess,
		ActiveRegion *	regFirst,
		ActiveRegion *	regLast
	)

Definition at line 260 of file sweep.

{
  ActiveRegion *reg, *regPrev;
  GLUhalfEdge *e, *ePrev;
 
  regPrev = regFirst;
  ePrev = regFirst->eUp;
  while( regPrev != regLast ) {
    regPrev->fixUpperEdge = TOOLS_GLU_FALSE;    /* placement was OK */
    reg = RegionBelow( regPrev );
    e = reg->eUp;
    if( e->Org != ePrev->Org ) {
      if( ! reg->fixUpperEdge ) {
    /* Remove the last left-going edge.  Even though there are no further
     * edges in the dictionary with this origin, there may be further
     * such edges in the mesh (if we are adding left edges to a vertex
     * that has already been processed).  Thus it is important to call
     * FinishRegion rather than just DeleteRegion.
     */
    static_FinishRegion( tess, regPrev );
    break;
      }
      /* If the edge below was a temporary edge introduced by
       * ConnectRightVertex, now is the time to fix it.
       */
      e = __gl_meshConnect( ePrev->Lprev, e->Sym );
      if (e == NULL) longjmp(tess->env,1);
      if ( !static_FixUpperEdge( reg, e ) ) longjmp(tess->env,1);
    }
 
    /* Relink edges so that ePrev->Onext == e */
    if( ePrev->Onext != e ) {
      if ( !__gl_meshSplice( e->Oprev, e ) ) longjmp(tess->env,1);
      if ( !__gl_meshSplice( ePrev, e ) ) longjmp(tess->env,1);
    }
    static_FinishRegion( tess, regPrev );   /* may change reg->eUp */
    ePrev = reg->eUp;
    regPrev = reg;
  }
  return ePrev;
}

static_FinishRegion()

inline void static_FinishRegion	(	GLUtesselator *	tess,
		ActiveRegion *	reg
	)

Definition at line 242 of file sweep.

{
  GLUhalfEdge *e = reg->eUp;
  GLUface *f = e->Lface;
 
  f->inside = reg->inside;
  f->anEdge = e;   /* optimization for __gl_meshTessellateMonoRegion() */
  static_DeleteRegion( tess, reg );
}

static_FixUpperEdge()

inline int static_FixUpperEdge	(	ActiveRegion *	reg,
		GLUhalfEdge *	newEdge
	)

Definition at line 142 of file sweep.

{
  assert( reg->fixUpperEdge );
  if ( !__gl_meshDelete( reg->eUp ) ) return 0;
  reg->fixUpperEdge = TOOLS_GLU_FALSE;
  reg->eUp = newEdge;
  newEdge->activeRegion = reg;
 
  return 1;
}

static_GetIntersectData()

inline void static_GetIntersectData	(	GLUtesselator *	tess,
		GLUvertex *	isect,
		GLUvertex *	orgUp,
		GLUvertex *	dstUp,
		GLUvertex *	orgLo,
		GLUvertex *	dstLo
	)

Definition at line 451 of file sweep.

{
  void *data[4];
  GLUfloat weights[4];
 
  data[0] = orgUp->data;
  data[1] = dstUp->data;
  data[2] = orgLo->data;
  data[3] = dstLo->data;
 
  isect->coords[0] = isect->coords[1] = isect->coords[2] = 0;
  static_VertexWeights( isect, orgUp, dstUp, &weights[0] );
  static_VertexWeights( isect, orgLo, dstLo, &weights[2] );
 
  static_CallCombine( tess, isect, data, weights, TOOLS_GLU_TRUE );
}

static_InitEdgeDict()

inline void static_InitEdgeDict

(

GLUtesselator *

tess

)

Definition at line 1138 of file sweep.

{
  /* __gl_dictListNewDict */
  tess->dict = dictNewDict( tess, (int (*)(void *, DictKey, DictKey)) static_EdgeLeq );
  if (tess->dict == NULL) longjmp(tess->env,1);
 
  static_AddSentinel( tess, -SENTINEL_COORD() );
  static_AddSentinel( tess, SENTINEL_COORD() );
}

static_InitPriorityQ()

inline int static_InitPriorityQ

(

GLUtesselator *

tess

)

Definition at line 1219 of file sweep.

{
  PriorityQ *pq;
  GLUvertex *v, *vHead;
 
  /* __gl_pqSortNewPriorityQ */
  pq = tess->pq = pqNewPriorityQ( (int (*)(PQkey, PQkey)) __gl_vertLeq );
  if (pq == NULL) return 0;
 
  vHead = &tess->mesh->vHead;
  for( v = vHead->next; v != vHead; v = v->next ) {
    v->pqHandle = pqInsert( pq, v ); /* __gl_pqSortInsert */
    if (v->pqHandle == LONG_MAX) break;
  }
  if (v != vHead || !pqInit( pq ) ) { /* __gl_pqSortInit */
    pqDeletePriorityQ(tess->pq);    /* __gl_pqSortDeletePriorityQ */
    tess->pq = NULL;
    return 0;
  }
 
  return 1;
}

static_IsWindingInside()

inline GLUboolean static_IsWindingInside	(	GLUtesselator *	tess,
		int	n
	)

Definition at line 214 of file sweep.

{
  switch( tess->windingRule ) {
  case GLU_TESS_WINDING_ODD:
    return (n & 1);
  case GLU_TESS_WINDING_NONZERO:
    return (n != 0);
  case GLU_TESS_WINDING_POSITIVE:
    return (n > 0);
  case GLU_TESS_WINDING_NEGATIVE:
    return (n < 0);
  case GLU_TESS_WINDING_ABS_GEQ_TWO:
    return (n >= 2) || (n <= -2);
  }
  /*LINTED*/
  assert( TOOLS_GLU_FALSE );
  /*NOTREACHED*/
  return TOOLS_GLU_FALSE;  /* avoid compiler complaints */
}

static_RemoveDegenerateEdges()

inline void static_RemoveDegenerateEdges

(

GLUtesselator *

tess

)

Definition at line 1185 of file sweep.

{
  GLUhalfEdge *e, *eNext, *eLnext;
  GLUhalfEdge *eHead = &tess->mesh->eHead;
 
  /*LINTED*/
  for( e = eHead->next; e != eHead; e = eNext ) {
    eNext = e->next;
    eLnext = e->Lnext;
 
    if( VertEq( e->Org, e->Dst ) && e->Lnext->Lnext != e ) {
      /* Zero-length edge, contour has at least 3 edges */
 
      static_SpliceMergeVertices( tess, eLnext, e );    /* deletes e->Org */
      if ( !__gl_meshDelete( e ) ) longjmp(tess->env,1); /* e is a self-loop */
      e = eLnext;
      eLnext = e->Lnext;
    }
    if( eLnext->Lnext == e ) {
      /* Degenerate contour (one or two edges) */
 
      if( eLnext != e ) {
    if( eLnext == eNext || eLnext == eNext->Sym ) { eNext = eNext->next; }
    if ( !__gl_meshDelete( eLnext ) ) longjmp(tess->env,1);
      }
      if( e == eNext || e == eNext->Sym ) { eNext = eNext->next; }
      if ( !__gl_meshDelete( e ) ) longjmp(tess->env,1);
    }
  }
}

static_RemoveDegenerateFaces()

inline int static_RemoveDegenerateFaces

(

GLUmesh *

mesh

)

Definition at line 1253 of file sweep.

{
  GLUface *f, *fNext;
  GLUhalfEdge *e;
 
  /*LINTED*/
  for( f = mesh->fHead.next; f != &mesh->fHead; f = fNext ) {
    fNext = f->next;
    e = f->anEdge;
    assert( e->Lnext != e );
 
    if( e->Lnext->Lnext == e ) {
      /* A face with only two edges */
      AddWinding( e->Onext, e );
      if ( !__gl_meshDelete( e ) ) return 0;
    }
  }
  return 1;
}

static_SpliceMergeVertices()

inline void static_SpliceMergeVertices	(	GLUtesselator *	tess,
		GLUhalfEdge *	e1,
		GLUhalfEdge *	e2
	)

Definition at line 414 of file sweep.

{
  void *data[4] = { NULL, NULL, NULL, NULL };
  GLUfloat weights[4] = { 0.5, 0.5, 0.0, 0.0 };
 
  data[0] = e1->Org->data;
  data[1] = e2->Org->data;
  static_CallCombine( tess, e1->Org, data, weights, TOOLS_GLU_FALSE );
  if ( !__gl_meshSplice( e1, e2 ) ) longjmp(tess->env,1);
}

static_SweepEvent()

void static_SweepEvent	(	GLUtesselator *	tess,
		GLUvertex *	vEvent
	)

Definition at line 1044 of file sweep.

{
  ActiveRegion *regUp, *reg;
  GLUhalfEdge *e, *eTopLeft, *eBottomLeft;
 
  tess->event = vEvent;     /* for access in EdgeLeq() */
  DebugEvent( tess );
 
  /* Check if this vertex is the right endpoint of an edge that is
   * already in the dictionary.  In this case we don't need to waste
   * time searching for the location to insert new edges.
   */
  e = vEvent->anEdge;
  while( e->activeRegion == NULL ) {
    e = e->Onext;
    if( e == vEvent->anEdge ) {
      /* All edges go right -- not incident to any processed edges */
      static_ConnectLeftVertex( tess, vEvent );
      return;
    }
  }
 
  /* Processing consists of two phases: first we "finish" all the
   * active regions where both the upper and lower edges terminate
   * at vEvent (ie. vEvent is closing off these regions).
   * We mark these faces "inside" or "outside" the polygon according
   * to their winding number, and delete the edges from the dictionary.
   * This takes care of all the left-going edges from vEvent.
   */
  regUp = static_TopLeftRegion( e->activeRegion );
  if (regUp == NULL) longjmp(tess->env,1);
  reg = RegionBelow( regUp );
  eTopLeft = reg->eUp;
  eBottomLeft = static_FinishLeftRegions( tess, reg, NULL );
 
  /* Next we process all the right-going edges from vEvent.  This
   * involves adding the edges to the dictionary, and creating the
   * associated "active regions" which record information about the
   * regions between adjacent dictionary edges.
   */
  if( eBottomLeft->Onext == eTopLeft ) {
    /* No right-going edges -- add a temporary "fixable" edge */
    static_ConnectRightVertex( tess, regUp, eBottomLeft );
  } else {
    static_AddRightEdges( tess, regUp, eBottomLeft->Onext, eTopLeft, eTopLeft, TOOLS_GLU_TRUE );
  }
}

static_TopLeftRegion()

inline ActiveRegion* static_TopLeftRegion

(

ActiveRegion *

reg

)

Definition at line 156 of file sweep.

{
  GLUvertex *org = reg->eUp->Org;
  GLUhalfEdge *e;
 
  /* Find the region above the uppermost edge with the same origin */
  do {
    reg = RegionAbove( reg );
  } while( reg->eUp->Org == org );
 
  /* If the edge above was a temporary edge introduced by ConnectRightVertex,
   * now is the time to fix it.
   */
  if( reg->fixUpperEdge ) {
    e = __gl_meshConnect( RegionBelow(reg)->eUp->Sym, reg->eUp->Lnext );
    if (e == NULL) return NULL;
    if ( !static_FixUpperEdge( reg, e ) ) return NULL;
    reg = RegionAbove( reg );
  }
  return reg;
}

static_TopRightRegion()

inline ActiveRegion* static_TopRightRegion

(

ActiveRegion *

reg

)

Definition at line 178 of file sweep.

{
  GLUvertex *dst = reg->eUp->Dst;
 
  /* Find the region above the uppermost edge with the same destination */
  do {
    reg = RegionAbove( reg );
  } while( reg->eUp->Dst == dst );
  return reg;
}

static_VertexWeights()

inline void static_VertexWeights	(	GLUvertex *	isect,
		GLUvertex *	org,
		GLUvertex *	dst,
		GLUfloat *	weights
	)

Definition at line 430 of file sweep.

{
  GLUdouble t1 = VertL1dist( org, isect );
  GLUdouble t2 = VertL1dist( dst, isect );
 
  weights[0] = float(0.5 * t2 / (t1 + t2));
  weights[1] = float(0.5 * t1 / (t1 + t2));
  isect->coords[0] += weights[0]*org->coords[0] + weights[1]*dst->coords[0];
  isect->coords[1] += weights[0]*org->coords[1] + weights[1]*dst->coords[1];
  isect->coords[2] += weights[0]*org->coords[2] + weights[1]*dst->coords[2];
}

static_WalkDirtyRegions()

void static_WalkDirtyRegions	(	GLUtesselator *	tess,
		ActiveRegion *	regUp
	)

Definition at line 736 of file sweep.

{
  ActiveRegion *regLo = RegionBelow(regUp);
  GLUhalfEdge *eUp, *eLo;
 
  for( ;; ) {
    /* Find the lowest dirty region (we walk from the bottom up). */
    while( regLo->dirty ) {
      regUp = regLo;
      regLo = RegionBelow(regLo);
    }
    if( ! regUp->dirty ) {
      regLo = regUp;
      regUp = RegionAbove( regUp );
      if( regUp == NULL || ! regUp->dirty ) {
    /* We've walked all the dirty regions */
    return;
      }
    }
    regUp->dirty = TOOLS_GLU_FALSE;
    eUp = regUp->eUp;
    eLo = regLo->eUp;
 
    if( eUp->Dst != eLo->Dst ) {
      /* Check that the edge ordering is obeyed at the Dst vertices. */
      if( static_CheckForLeftSplice( tess, regUp )) {
 
    /* If the upper or lower edge was marked fixUpperEdge, then
     * we no longer need it (since these edges are needed only for
     * vertices which otherwise have no right-going edges).
     */
    if( regLo->fixUpperEdge ) {
      static_DeleteRegion( tess, regLo );
      if ( !__gl_meshDelete( eLo ) ) longjmp(tess->env,1);
      regLo = RegionBelow( regUp );
      eLo = regLo->eUp;
    } else if( regUp->fixUpperEdge ) {
      static_DeleteRegion( tess, regUp );
      if ( !__gl_meshDelete( eUp ) ) longjmp(tess->env,1);
      regUp = RegionAbove( regLo );
      eUp = regUp->eUp;
    }
      }
    }
    if( eUp->Org != eLo->Org ) {
      if(    eUp->Dst != eLo->Dst
      && ! regUp->fixUpperEdge && ! regLo->fixUpperEdge
      && (eUp->Dst == tess->event || eLo->Dst == tess->event) )
      {
    /* When all else fails in CheckForIntersect(), it uses tess->event
     * as the intersection location.  To make this possible, it requires
     * that tess->event lie between the upper and lower edges, and also
     * that neither of these is marked fixUpperEdge (since in the worst
     * case it might splice one of these edges into tess->event, and
     * violate the invariant that fixable edges are the only right-going
     * edge from their associated vertex).
     */
    if( static_CheckForIntersect( tess, regUp )) {
      /* WalkDirtyRegions() was called recursively; we're done */
      return;
    }
      } else {
    /* Even though we can't use CheckForIntersect(), the Org vertices
     * may violate the dictionary edge ordering.  Check and correct this.
     */
    (void) static_CheckForRightSplice( tess, regUp );
      }
    }
    if( eUp->Org == eLo->Org && eUp->Dst == eLo->Dst ) {
      /* A degenerate loop consisting of only two edges -- delete it. */
      AddWinding( eLo, eUp );
      static_DeleteRegion( tess, regUp );
      if ( !__gl_meshDelete( eUp ) ) longjmp(tess->env,1);
      regUp = RegionAbove( regLo );
    }
  }
}