+++ /dev/null
-/*
- * SGI FREE SOFTWARE LICENSE B (Version 2.0, Sept. 18, 2008)
- * Copyright (C) 1991-2000 Silicon Graphics, Inc. All Rights Reserved.
- *
- * Permission is hereby granted, free of charge, to any person obtaining a
- * copy of this software and associated documentation files (the "Software"),
- * to deal in the Software without restriction, including without limitation
- * the rights to use, copy, modify, merge, publish, distribute, sublicense,
- * and/or sell copies of the Software, and to permit persons to whom the
- * Software is furnished to do so, subject to the following conditions:
- *
- * The above copyright notice including the dates of first publication and
- * either this permission notice or a reference to
- * http://oss.sgi.com/projects/FreeB/
- * shall be included in all copies or substantial portions of the Software.
- *
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
- * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
- * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
- * SILICON GRAPHICS, INC. BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
- * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF
- * OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
- * SOFTWARE.
- *
- * Except as contained in this notice, the name of Silicon Graphics, Inc.
- * shall not be used in advertising or otherwise to promote the sale, use or
- * other dealings in this Software without prior written authorization from
- * Silicon Graphics, Inc.
- */
-/*
-** Author: Eric Veach, July 1994.
-**
-*/
-
-#include "gluos.h"
-#include <assert.h>
-#include <stddef.h>
-#include <setjmp.h> /* longjmp */
-#include <limits.h> /* LONG_MAX */
-
-#include "mesh.h"
-#include "geom.h"
-#include "tess.h"
-#include "dict.h"
-#include "priorityq.h"
-#include "memalloc.h"
-#include "sweep.h"
-
-#ifndef TRUE
-#define TRUE 1
-#endif
-#ifndef FALSE
-#define FALSE 0
-#endif
-
-#ifdef FOR_TRITE_TEST_PROGRAM
-extern void DebugEvent( GLUtesselator *tess );
-#else
-#define DebugEvent( tess )
-#endif
-
-/*
- * Invariants for the Edge Dictionary.
- * - each pair of adjacent edges e2=Succ(e1) satisfies EdgeLeq(e1,e2)
- * at any valid location of the sweep event
- * - if EdgeLeq(e2,e1) as well (at any valid sweep event), then e1 and e2
- * share a common endpoint
- * - for each e, e->Dst has been processed, but not e->Org
- * - each edge e satisfies VertLeq(e->Dst,event) && VertLeq(event,e->Org)
- * where "event" is the current sweep line event.
- * - no edge e has zero length
- *
- * Invariants for the Mesh (the processed portion).
- * - the portion of the mesh left of the sweep line is a planar graph,
- * ie. there is *some* way to embed it in the plane
- * - no processed edge has zero length
- * - no two processed vertices have identical coordinates
- * - each "inside" region is monotone, ie. can be broken into two chains
- * of monotonically increasing vertices according to VertLeq(v1,v2)
- * - a non-invariant: these chains may intersect (very slightly)
- *
- * Invariants for the Sweep.
- * - if none of the edges incident to the event vertex have an activeRegion
- * (ie. none of these edges are in the edge dictionary), then the vertex
- * has only right-going edges.
- * - if an edge is marked "fixUpperEdge" (it is a temporary edge introduced
- * by ConnectRightVertex), then it is the only right-going edge from
- * its associated vertex. (This says that these edges exist only
- * when it is necessary.)
- */
-
-#undef MAX
-#undef MIN
-#define MAX(x,y) ((x) >= (y) ? (x) : (y))
-#define MIN(x,y) ((x) <= (y) ? (x) : (y))
-
-/* When we merge two edges into one, we need to compute the combined
- * winding of the new edge.
- */
-#define AddWinding(eDst,eSrc) (eDst->winding += eSrc->winding, \
- eDst->Sym->winding += eSrc->Sym->winding)
-
-static void SweepEvent( GLUtesselator *tess, GLUvertex *vEvent );
-static void WalkDirtyRegions( GLUtesselator *tess, ActiveRegion *regUp );
-static int CheckForRightSplice( GLUtesselator *tess, ActiveRegion *regUp );
-
-static int EdgeLeq( GLUtesselator *tess, ActiveRegion *reg1,
- ActiveRegion *reg2 )
-/*
- * Both edges must be directed from right to left (this is the canonical
- * direction for the upper edge of each region).
- *
- * The strategy is to evaluate a "t" value for each edge at the
- * current sweep line position, given by tess->event. The calculations
- * are designed to be very stable, but of course they are not perfect.
- *
- * Special case: if both edge destinations are at the sweep event,
- * we sort the edges by slope (they would otherwise compare equally).
- */
-{
- GLUvertex *event = tess->event;
- GLUhalfEdge *e1, *e2;
- GLdouble 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 void DeleteRegion( GLUtesselator *tess, ActiveRegion *reg )
-{
- 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 int FixUpperEdge( ActiveRegion *reg, GLUhalfEdge *newEdge )
-/*
- * Replace an upper edge which needs fixing (see ConnectRightVertex).
- */
-{
- assert( reg->fixUpperEdge );
- if ( !__gl_meshDelete( reg->eUp ) ) return 0;
- reg->fixUpperEdge = FALSE;
- reg->eUp = newEdge;
- newEdge->activeRegion = reg;
-
- return 1;
-}
-
-static ActiveRegion *TopLeftRegion( ActiveRegion *reg )
-{
- 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 ( !FixUpperEdge( reg, e ) ) return NULL;
- reg = RegionAbove( reg );
- }
- return reg;
-}
-
-static ActiveRegion *TopRightRegion( ActiveRegion *reg )
-{
- 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 ActiveRegion *AddRegionBelow( GLUtesselator *tess,
- ActiveRegion *regAbove,
- GLUhalfEdge *eNewUp )
-/*
- * Add a new active region to the sweep line, *somewhere* below "regAbove"
- * (according to where the new edge belongs in the sweep-line dictionary).
- * The upper edge of the new region will be "eNewUp".
- * Winding number and "inside" flag are not updated.
- */
-{
- 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 = FALSE;
- regNew->sentinel = FALSE;
- regNew->dirty = FALSE;
-
- eNewUp->activeRegion = regNew;
- return regNew;
-}
-
-static GLboolean IsWindingInside( GLUtesselator *tess, int n )
-{
- 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( FALSE );
- /*NOTREACHED*/
- return GL_FALSE; /* avoid compiler complaints */
-}
-
-
-static void ComputeWinding( GLUtesselator *tess, ActiveRegion *reg )
-{
- reg->windingNumber = RegionAbove(reg)->windingNumber + reg->eUp->winding;
- reg->inside = IsWindingInside( tess, reg->windingNumber );
-}
-
-
-static void FinishRegion( GLUtesselator *tess, ActiveRegion *reg )
-/*
- * Delete a region from the sweep line. This happens when the upper
- * and lower chains of a region meet (at a vertex on the sweep line).
- * The "inside" flag is copied to the appropriate mesh face (we could
- * not do this before -- since the structure of the mesh is always
- * changing, this face may not have even existed until now).
- */
-{
- GLUhalfEdge *e = reg->eUp;
- GLUface *f = e->Lface;
-
- f->inside = reg->inside;
- f->anEdge = e; /* optimization for __gl_meshTessellateMonoRegion() */
- DeleteRegion( tess, reg );
-}
-
-
-static GLUhalfEdge *FinishLeftRegions( GLUtesselator *tess,
- ActiveRegion *regFirst, ActiveRegion *regLast )
-/*
- * We are given a vertex with one or more left-going edges. All affected
- * edges should be in the edge dictionary. Starting at regFirst->eUp,
- * we walk down deleting all regions where both edges have the same
- * origin vOrg. At the same time we copy the "inside" flag from the
- * active region to the face, since at this point each face will belong
- * to at most one region (this was not necessarily true until this point
- * in the sweep). The walk stops at the region above regLast; if regLast
- * is NULL we walk as far as possible. At the same time we relink the
- * mesh if necessary, so that the ordering of edges around vOrg is the
- * same as in the dictionary.
- */
-{
- ActiveRegion *reg, *regPrev;
- GLUhalfEdge *e, *ePrev;
-
- regPrev = regFirst;
- ePrev = regFirst->eUp;
- while( regPrev != regLast ) {
- regPrev->fixUpperEdge = 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.
- */
- 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 ( !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);
- }
- FinishRegion( tess, regPrev ); /* may change reg->eUp */
- ePrev = reg->eUp;
- regPrev = reg;
- }
- return ePrev;
-}
-
-
-static void AddRightEdges( GLUtesselator *tess, ActiveRegion *regUp,
- GLUhalfEdge *eFirst, GLUhalfEdge *eLast, GLUhalfEdge *eTopLeft,
- GLboolean cleanUp )
-/*
- * Purpose: insert right-going edges into the edge dictionary, and update
- * winding numbers and mesh connectivity appropriately. All right-going
- * edges share a common origin vOrg. Edges are inserted CCW starting at
- * eFirst; the last edge inserted is eLast->Oprev. If vOrg has any
- * left-going edges already processed, then eTopLeft must be the edge
- * such that an imaginary upward vertical segment from vOrg would be
- * contained between eTopLeft->Oprev and eTopLeft; otherwise eTopLeft
- * should be NULL.
- */
-{
- ActiveRegion *reg, *regPrev;
- GLUhalfEdge *e, *ePrev;
- int firstTime = TRUE;
-
- /* Insert the new right-going edges in the dictionary */
- e = eFirst;
- do {
- assert( VertLeq( e->Org, e->Dst ));
- 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 = 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 = TRUE;
- if( ! firstTime && CheckForRightSplice( tess, regPrev )) {
- AddWinding( e, ePrev );
- DeleteRegion( tess, regPrev );
- if ( !__gl_meshDelete( ePrev ) ) longjmp(tess->env,1);
- }
- firstTime = FALSE;
- regPrev = reg;
- ePrev = e;
- }
- regPrev->dirty = TRUE;
- assert( regPrev->windingNumber - e->winding == reg->windingNumber );
-
- if( cleanUp ) {
- /* Check for intersections between newly adjacent edges. */
- WalkDirtyRegions( tess, regPrev );
- }
-}
-
-
-static void CallCombine( GLUtesselator *tess, GLUvertex *isect,
- void *data[4], GLfloat weights[4], int needed )
-{
- GLdouble 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 = TRUE;
- }
- }
-}
-
-static void SpliceMergeVertices( GLUtesselator *tess, GLUhalfEdge *e1,
- GLUhalfEdge *e2 )
-/*
- * Two vertices with idential coordinates are combined into one.
- * e1->Org is kept, while e2->Org is discarded.
- */
-{
- void *data[4] = { NULL, NULL, NULL, NULL };
- GLfloat weights[4] = { 0.5, 0.5, 0.0, 0.0 };
-
- data[0] = e1->Org->data;
- data[1] = e2->Org->data;
- CallCombine( tess, e1->Org, data, weights, FALSE );
- if ( !__gl_meshSplice( e1, e2 ) ) longjmp(tess->env,1);
-}
-
-static void VertexWeights( GLUvertex *isect, GLUvertex *org, GLUvertex *dst,
- GLfloat *weights )
-/*
- * Find some weights which describe how the intersection vertex is
- * a linear combination of "org" and "dest". Each of the two edges
- * which generated "isect" is allocated 50% of the weight; each edge
- * splits the weight between its org and dst according to the
- * relative distance to "isect".
- */
-{
- GLdouble t1 = VertL1dist( org, isect );
- GLdouble t2 = VertL1dist( dst, isect );
-
- weights[0] = 0.5 * t2 / (t1 + t2);
- weights[1] = 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 void GetIntersectData( GLUtesselator *tess, GLUvertex *isect,
- GLUvertex *orgUp, GLUvertex *dstUp,
- GLUvertex *orgLo, GLUvertex *dstLo )
-/*
- * We've computed a new intersection point, now we need a "data" pointer
- * from the user so that we can refer to this new vertex in the
- * rendering callbacks.
- */
-{
- void *data[4];
- GLfloat 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;
- VertexWeights( isect, orgUp, dstUp, &weights[0] );
- VertexWeights( isect, orgLo, dstLo, &weights[2] );
-
- CallCombine( tess, isect, data, weights, TRUE );
-}
-
-static int CheckForRightSplice( GLUtesselator *tess, ActiveRegion *regUp )
-/*
- * Check the upper and lower edge of "regUp", to make sure that the
- * eUp->Org is above eLo, or eLo->Org is below eUp (depending on which
- * origin is leftmost).
- *
- * The main purpose is to splice right-going edges with the same
- * dest vertex and nearly identical slopes (ie. we can't distinguish
- * the slopes numerically). However the splicing can also help us
- * to recover from numerical errors. For example, suppose at one
- * point we checked eUp and eLo, and decided that eUp->Org is barely
- * above eLo. Then later, we split eLo into two edges (eg. from
- * a splice operation like this one). This can change the result of
- * our test so that now eUp->Org is incident to eLo, or barely below it.
- * We must correct this condition to maintain the dictionary invariants.
- *
- * One possibility is to check these edges for intersection again
- * (ie. CheckForIntersect). This is what we do if possible. However
- * CheckForIntersect requires that tess->event lies between eUp and eLo,
- * so that it has something to fall back on when the intersection
- * calculation gives us an unusable answer. So, for those cases where
- * we can't check for intersection, this routine fixes the problem
- * by just splicing the offending vertex into the other edge.
- * This is a guaranteed solution, no matter how degenerate things get.
- * Basically this is a combinatorial solution to a numerical problem.
- */
-{
- 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 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 = TRUE;
-
- } else if( eUp->Org != eLo->Org ) {
- /* merge the two vertices, discarding eUp->Org */
- pqDelete( tess->pq, eUp->Org->pqHandle ); /* __gl_pqSortDelete */
- SpliceMergeVertices( tess, eLo->Oprev, eUp );
- }
- } else {
- if( EdgeSign( eUp->Dst, eLo->Org, eUp->Org ) < 0 ) return FALSE;
-
- /* eLo->Org appears to be above eUp, so splice eLo->Org into eUp */
- RegionAbove(regUp)->dirty = regUp->dirty = TRUE;
- if (__gl_meshSplitEdge( eUp->Sym ) == NULL) longjmp(tess->env,1);
- if ( !__gl_meshSplice( eLo->Oprev, eUp ) ) longjmp(tess->env,1);
- }
- return TRUE;
-}
-
-static int CheckForLeftSplice( GLUtesselator *tess, ActiveRegion *regUp )
-/*
- * Check the upper and lower edge of "regUp", to make sure that the
- * eUp->Dst is above eLo, or eLo->Dst is below eUp (depending on which
- * destination is rightmost).
- *
- * Theoretically, this should always be true. However, splitting an edge
- * into two pieces can change the results of previous tests. For example,
- * suppose at one point we checked eUp and eLo, and decided that eUp->Dst
- * is barely above eLo. Then later, we split eLo into two edges (eg. from
- * a splice operation like this one). This can change the result of
- * the test so that now eUp->Dst is incident to eLo, or barely below it.
- * We must correct this condition to maintain the dictionary invariants
- * (otherwise new edges might get inserted in the wrong place in the
- * dictionary, and bad stuff will happen).
- *
- * We fix the problem by just splicing the offending vertex into the
- * other edge.
- */
-{
- 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 FALSE;
-
- /* eLo->Dst is above eUp, so splice eLo->Dst into eUp */
- RegionAbove(regUp)->dirty = regUp->dirty = 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 FALSE;
-
- /* eUp->Dst is below eLo, so splice eUp->Dst into eLo */
- regUp->dirty = regLo->dirty = 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 TRUE;
-}
-
-
-static int CheckForIntersect( GLUtesselator *tess, ActiveRegion *regUp )
-/*
- * Check the upper and lower edges of the given region to see if
- * they intersect. If so, create the intersection and add it
- * to the data structures.
- *
- * Returns TRUE if adding the new intersection resulted in a recursive
- * call to AddRightEdges(); in this case all "dirty" regions have been
- * checked for intersections, and possibly regUp has been deleted.
- */
-{
- 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;
- GLdouble 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 FALSE; /* right endpoints are the same */
-
- tMinUp = MIN( orgUp->t, dstUp->t );
- tMaxLo = MAX( orgLo->t, dstLo->t );
- if( tMinUp > tMaxLo ) return FALSE; /* t ranges do not overlap */
-
- if( VertLeq( orgUp, orgLo )) {
- if( EdgeSign( dstLo, orgUp, orgLo ) > 0 ) return FALSE;
- } else {
- if( EdgeSign( dstUp, orgLo, orgUp ) < 0 ) return 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( MIN( orgUp->t, dstUp->t ) <= isect.t );
- assert( isect.t <= MAX( orgLo->t, dstLo->t ));
- assert( MIN( dstLo->s, dstUp->s ) <= isect.s );
- assert( isect.s <= 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) CheckForRightSplice( tess, regUp );
- return 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 = TopLeftRegion( regUp );
- if (regUp == NULL) longjmp(tess->env,1);
- eUp = RegionBelow(regUp)->eUp;
- FinishLeftRegions( tess, RegionBelow(regUp), regLo );
- AddRightEdges( tess, regUp, eUp->Oprev, eUp, eUp, TRUE );
- return 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 = TopRightRegion( regUp );
- e = RegionBelow(regUp)->eUp->Rprev;
- regLo->eUp = eLo->Oprev;
- eLo = FinishLeftRegions( tess, regLo, NULL );
- AddRightEdges( tess, regUp, eLo->Onext, eUp->Rprev, e, TRUE );
- return 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 = 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 = 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 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);
- }
- GetIntersectData( tess, eUp->Org, orgUp, dstUp, orgLo, dstLo );
- RegionAbove(regUp)->dirty = regUp->dirty = regLo->dirty = TRUE;
- return FALSE;
-}
-
-static void WalkDirtyRegions( GLUtesselator *tess, ActiveRegion *regUp )
-/*
- * When the upper or lower edge of any region changes, the region is
- * marked "dirty". This routine walks through all the dirty regions
- * and makes sure that the dictionary invariants are satisfied
- * (see the comments at the beginning of this file). Of course
- * new dirty regions can be created as we make changes to restore
- * the invariants.
- */
-{
- 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 = FALSE;
- eUp = regUp->eUp;
- eLo = regLo->eUp;
-
- if( eUp->Dst != eLo->Dst ) {
- /* Check that the edge ordering is obeyed at the Dst vertices. */
- if( 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 ) {
- DeleteRegion( tess, regLo );
- if ( !__gl_meshDelete( eLo ) ) longjmp(tess->env,1);
- regLo = RegionBelow( regUp );
- eLo = regLo->eUp;
- } else if( regUp->fixUpperEdge ) {
- 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( 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) 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 );
- DeleteRegion( tess, regUp );
- if ( !__gl_meshDelete( eUp ) ) longjmp(tess->env,1);
- regUp = RegionAbove( regLo );
- }
- }
-}
-
-
-static void ConnectRightVertex( GLUtesselator *tess, ActiveRegion *regUp,
- GLUhalfEdge *eBottomLeft )
-/*
- * Purpose: connect a "right" vertex vEvent (one where all edges go left)
- * to the unprocessed portion of the mesh. Since there are no right-going
- * edges, two regions (one above vEvent and one below) are being merged
- * into one. "regUp" is the upper of these two regions.
- *
- * There are two reasons for doing this (adding a right-going edge):
- * - if the two regions being merged are "inside", we must add an edge
- * to keep them separated (the combined region would not be monotone).
- * - in any case, we must leave some record of vEvent in the dictionary,
- * so that we can merge vEvent with features that we have not seen yet.
- * For example, maybe there is a vertical edge which passes just to
- * the right of vEvent; we would like to splice vEvent into this edge.
- *
- * However, we don't want to connect vEvent to just any vertex. We don''t
- * want the new edge to cross any other edges; otherwise we will create
- * intersection vertices even when the input data had no self-intersections.
- * (This is a bad thing; if the user's input data has no intersections,
- * we don't want to generate any false intersections ourselves.)
- *
- * Our eventual goal is to connect vEvent to the leftmost unprocessed
- * vertex of the combined region (the union of regUp and regLo).
- * But because of unseen vertices with all right-going edges, and also
- * new vertices which may be created by edge intersections, we don''t
- * know where that leftmost unprocessed vertex is. In the meantime, we
- * connect vEvent to the closest vertex of either chain, and mark the region
- * as "fixUpperEdge". This flag says to delete and reconnect this edge
- * to the next processed vertex on the boundary of the combined region.
- * Quite possibly the vertex we connected to will turn out to be the
- * closest one, in which case we won''t need to make any changes.
- */
-{
- GLUhalfEdge *eNew;
- GLUhalfEdge *eTopLeft = eBottomLeft->Onext;
- ActiveRegion *regLo = RegionBelow(regUp);
- GLUhalfEdge *eUp = regUp->eUp;
- GLUhalfEdge *eLo = regLo->eUp;
- int degenerate = FALSE;
-
- if( eUp->Dst != eLo->Dst ) {
- (void) 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 = TopLeftRegion( regUp );
- if (regUp == NULL) longjmp(tess->env,1);
- eTopLeft = RegionBelow( regUp )->eUp;
- FinishLeftRegions( tess, RegionBelow(regUp), regLo );
- degenerate = TRUE;
- }
- if( VertEq( eLo->Org, tess->event )) {
- if ( !__gl_meshSplice( eBottomLeft, eLo->Oprev ) ) longjmp(tess->env,1);
- eBottomLeft = FinishLeftRegions( tess, regLo, NULL );
- degenerate = TRUE;
- }
- if( degenerate ) {
- AddRightEdges( tess, regUp, eBottomLeft->Onext, eTopLeft, eTopLeft, 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.
- */
- AddRightEdges( tess, regUp, eNew, eNew->Onext, eNew->Onext, FALSE );
- eNew->Sym->activeRegion->fixUpperEdge = TRUE;
- WalkDirtyRegions( tess, regUp );
-}
-
-/* Because vertices at exactly the same location are merged together
- * before we process the sweep event, some degenerate cases can't occur.
- * However if someone eventually makes the modifications required to
- * merge features which are close together, the cases below marked
- * TOLERANCE_NONZERO will be useful. They were debugged before the
- * code to merge identical vertices in the main loop was added.
- */
-#define TOLERANCE_NONZERO FALSE
-
-static void ConnectLeftDegenerate( GLUtesselator *tess,
- ActiveRegion *regUp, GLUvertex *vEvent )
-/*
- * The event vertex lies exacty on an already-processed edge or vertex.
- * Adding the new vertex involves splicing it into the already-processed
- * part of the mesh.
- */
-{
- 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 );
- 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 = FALSE;
- }
- if ( !__gl_meshSplice( vEvent->anEdge, e ) ) longjmp(tess->env,1);
- 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 );
- regUp = 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 */
- 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;
- }
- AddRightEdges( tess, regUp, eTopRight->Onext, eLast, eTopLeft, TRUE );
-}
-
-
-static void ConnectLeftVertex( GLUtesselator *tess, GLUvertex *vEvent )
-/*
- * Purpose: connect a "left" vertex (one where both edges go right)
- * to the processed portion of the mesh. Let R be the active region
- * containing vEvent, and let U and L be the upper and lower edge
- * chains of R. There are two possibilities:
- *
- * - the normal case: split R into two regions, by connecting vEvent to
- * the rightmost vertex of U or L lying to the left of the sweep line
- *
- * - the degenerate case: if vEvent is close enough to U or L, we
- * merge vEvent into that edge chain. The subcases are:
- * - merging with the rightmost vertex of U or L
- * - merging with the active edge of U or L
- * - merging with an already-processed portion of U or L
- */
-{
- 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 ) {
- 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 ( !FixUpperEdge( reg, eNew ) ) longjmp(tess->env,1);
- } else {
- ComputeWinding( tess, AddRegionBelow( tess, regUp, eNew ));
- }
- 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.
- */
- AddRightEdges( tess, regUp, vEvent->anEdge, vEvent->anEdge, NULL, TRUE );
- }
-}
-
-
-static void SweepEvent( GLUtesselator *tess, GLUvertex *vEvent )
-/*
- * Does everything necessary when the sweep line crosses a vertex.
- * Updates the mesh and the edge dictionary.
- */
-{
- 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 */
- 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 = TopLeftRegion( e->activeRegion );
- if (regUp == NULL) longjmp(tess->env,1);
- reg = RegionBelow( regUp );
- eTopLeft = reg->eUp;
- eBottomLeft = 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 */
- ConnectRightVertex( tess, regUp, eBottomLeft );
- } else {
- AddRightEdges( tess, regUp, eBottomLeft->Onext, eTopLeft, eTopLeft, TRUE );
- }
-}
-
-
-/* Make the sentinel coordinates big enough that they will never be
- * merged with real input features. (Even with the largest possible
- * input contour and the maximum tolerance of 1.0, no merging will be
- * done with coordinates larger than 3 * GLU_TESS_MAX_COORD).
- */
-#define SENTINEL_COORD (4 * GLU_TESS_MAX_COORD)
-
-static void AddSentinel( GLUtesselator *tess, GLdouble t )
-/*
- * We add two sentinel edges above and below all other edges,
- * to avoid special cases at the top and bottom.
- */
-{
- 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 = FALSE;
- reg->fixUpperEdge = FALSE;
- reg->sentinel = TRUE;
- reg->dirty = FALSE;
- reg->nodeUp = dictInsert( tess->dict, reg ); /* __gl_dictListInsertBefore */
- if (reg->nodeUp == NULL) longjmp(tess->env,1);
-}
-
-
-static void InitEdgeDict( GLUtesselator *tess )
-/*
- * We maintain an ordering of edge intersections with the sweep line.
- * This order is maintained in a dynamic dictionary.
- */
-{
- /* __gl_dictListNewDict */
- tess->dict = dictNewDict( tess, (int (*)(void *, DictKey, DictKey)) EdgeLeq );
- if (tess->dict == NULL) longjmp(tess->env,1);
-
- AddSentinel( tess, -SENTINEL_COORD );
- AddSentinel( tess, SENTINEL_COORD );
-}
-
-
-static void DoneEdgeDict( GLUtesselator *tess )
-{
- 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 );
- assert( ++fixedEdges == 1 );
- }
- assert( reg->windingNumber == 0 );
- DeleteRegion( tess, reg );
-/* __gl_meshDelete( reg->eUp );*/
- }
- dictDeleteDict( tess->dict ); /* __gl_dictListDeleteDict */
-}
-
-
-static void RemoveDegenerateEdges( GLUtesselator *tess )
-/*
- * Remove zero-length edges, and contours with fewer than 3 vertices.
- */
-{
- 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 */
-
- 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 int InitPriorityQ( GLUtesselator *tess )
-/*
- * Insert all vertices into the priority queue which determines the
- * order in which vertices cross the sweep line.
- */
-{
- 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 void DonePriorityQ( GLUtesselator *tess )
-{
- pqDeletePriorityQ( tess->pq ); /* __gl_pqSortDeletePriorityQ */
-}
-
-
-static int RemoveDegenerateFaces( GLUmesh *mesh )
-/*
- * Delete any degenerate faces with only two edges. WalkDirtyRegions()
- * will catch almost all of these, but it won't catch degenerate faces
- * produced by splice operations on already-processed edges.
- * The two places this can happen are in FinishLeftRegions(), when
- * we splice in a "temporary" edge produced by ConnectRightVertex(),
- * and in CheckForLeftSplice(), where we splice already-processed
- * edges to ensure that our dictionary invariants are not violated
- * by numerical errors.
- *
- * In both these cases it is *very* dangerous to delete the offending
- * edge at the time, since one of the routines further up the stack
- * will sometimes be keeping a pointer to that edge.
- */
-{
- 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;
-}
-
-int __gl_computeInterior( GLUtesselator *tess )
-/*
- * __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.
- */
-{
- GLUvertex *v, *vNext;
-
- tess->fatalError = 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)
- */
- RemoveDegenerateEdges( tess );
- if ( !InitPriorityQ( tess ) ) return 0; /* if error */
- 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*/
- SpliceMergeVertices( tess, v->anEdge, vNext->anEdge );
- }
- SweepEvent( tess, v );
- }
-
- /* Set tess->event for debugging purposes */
- /* __GL_DICTLISTKEY */ /* __GL_DICTLISTMIN */
- tess->event = ((ActiveRegion *) dictKey( dictMin( tess->dict )))->eUp->Org;
- DebugEvent( tess );
- DoneEdgeDict( tess );
- DonePriorityQ( tess );
-
- if ( !RemoveDegenerateFaces( tess->mesh ) ) return 0;
- __gl_meshCheckMesh( tess->mesh );
-
- return 1;
-}
projects / mesa.git / blobdiff