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Diffstat (limited to 'libtess/sweep.c')
| -rw-r--r-- | libtess/sweep.c | 1362 |
1 files changed, 0 insertions, 1362 deletions
diff --git a/libtess/sweep.c b/libtess/sweep.c deleted file mode 100644 index 753fd14..0000000 --- a/libtess/sweep.c +++ /dev/null @@ -1,1362 +0,0 @@ -/* -** License Applicability. Except to the extent portions of this file are -** made subject to an alternative license as permitted in the SGI Free -** Software License B, Version 1.1 (the "License"), the contents of this -** file are subject only to the provisions of the License. You may not use -** this file except in compliance with the License. You may obtain a copy -** of the License at Silicon Graphics, Inc., attn: Legal Services, 1600 -** Amphitheatre Parkway, Mountain View, CA 94043-1351, or at: -** -** http://oss.sgi.com/projects/FreeB -** -** Note that, as provided in the License, the Software is distributed on an -** "AS IS" basis, with ALL EXPRESS AND IMPLIED WARRANTIES AND CONDITIONS -** DISCLAIMED, INCLUDING, WITHOUT LIMITATION, ANY IMPLIED WARRANTIES AND -** CONDITIONS OF MERCHANTABILITY, SATISFACTORY QUALITY, FITNESS FOR A -** PARTICULAR PURPOSE, AND NON-INFRINGEMENT. -** -** Original Code. The Original Code is: OpenGL Sample Implementation, -** Version 1.2.1, released January 26, 2000, developed by Silicon Graphics, -** Inc. The Original Code is Copyright (c) 1991-2000 Silicon Graphics, Inc. -** Copyright in any portions created by third parties is as indicated -** elsewhere herein. All Rights Reserved. -** -** Additional Notice Provisions: The application programming interfaces -** established by SGI in conjunction with the Original Code are The -** OpenGL(R) Graphics System: A Specification (Version 1.2.1), released -** April 1, 1999; The OpenGL(R) Graphics System Utility Library (Version -** 1.3), released November 4, 1998; and OpenGL(R) Graphics with the X -** Window System(R) (Version 1.3), released October 19, 1998. This software -** was created using the OpenGL(R) version 1.2.1 Sample Implementation -** published by SGI, but has not been independently verified as being -** compliant with the OpenGL(R) version 1.2.1 Specification. -** -*/ -/* -** Author: Eric Veach, July 1994. -** -** $Date$ $Revision$ -** $Header$ -*/ - -#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" - -#define TRUE 1 -#define FALSE 0 - -#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.) - */ - -#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; -} |