pelya
1704 lines
51 KiB
C
1704 lines
51 KiB
C
/*
|
|
* 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.
|
|
*
|
|
* OpenGL ES 1.0 CM port of GLU by Mike Gorchak <mike@malva.ua>
|
|
**
|
|
*/
|
|
|
|
#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.)
|
|
*/
|
|
|
|
#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);
|
|
|
|
/*
|
|
* 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).
|
|
*/
|
|
static int EdgeLeq(GLUtesselator* tess, ActiveRegion* reg1, ActiveRegion* reg2)
|
|
{
|
|
GLUvertex* event=tess->event;
|
|
GLUhalfEdge* e1;
|
|
GLUhalfEdge* e2;
|
|
GLfloat 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);
|
|
}
|
|
|
|
/*
|
|
* Replace an upper edge which needs fixing (see ConnectRightVertex).
|
|
*/
|
|
static int FixUpperEdge(ActiveRegion* reg, GLUhalfEdge* newEdge)
|
|
{
|
|
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;
|
|
}
|
|
|
|
/*
|
|
* 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.
|
|
*/
|
|
static ActiveRegion* AddRegionBelow(GLUtesselator* tess, ActiveRegion* regAbove,
|
|
GLUhalfEdge* eNewUp)
|
|
{
|
|
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*/
|
|
/* avoid compiler complaints */
|
|
return GL_FALSE;
|
|
}
|
|
|
|
static void ComputeWinding(GLUtesselator* tess, ActiveRegion* reg)
|
|
{
|
|
reg->windingNumber=RegionAbove(reg)->windingNumber+reg->eUp->winding;
|
|
reg->inside=IsWindingInside(tess, reg->windingNumber);
|
|
}
|
|
|
|
/*
|
|
* 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).
|
|
*/
|
|
static void FinishRegion(GLUtesselator* tess, ActiveRegion* reg)
|
|
{
|
|
GLUhalfEdge* e=reg->eUp;
|
|
GLUface* f=e->Lface;
|
|
|
|
f->inside=reg->inside;
|
|
/* optimization for __gl_meshTessellateMonoRegion() */
|
|
f->anEdge=e;
|
|
DeleteRegion(tess, reg);
|
|
}
|
|
|
|
/*
|
|
* 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.
|
|
*/
|
|
static GLUhalfEdge* FinishLeftRegions(GLUtesselator* tess, ActiveRegion* regFirst,
|
|
ActiveRegion* regLast)
|
|
{
|
|
ActiveRegion* reg;
|
|
ActiveRegion* regPrev;
|
|
GLUhalfEdge* e;
|
|
GLUhalfEdge* ePrev;
|
|
|
|
regPrev=regFirst;
|
|
ePrev=regFirst->eUp;
|
|
while (regPrev!=regLast)
|
|
{
|
|
/* placement was OK */
|
|
regPrev->fixUpperEdge=FALSE;
|
|
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);
|
|
}
|
|
}
|
|
|
|
/* may change reg->eUp */
|
|
FinishRegion(tess, regPrev);
|
|
ePrev=reg->eUp;
|
|
regPrev=reg;
|
|
}
|
|
|
|
return ePrev;
|
|
}
|
|
|
|
/*
|
|
* 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.
|
|
*/
|
|
static void AddRightEdges(GLUtesselator* tess, ActiveRegion* regUp,
|
|
GLUhalfEdge* eFirst, GLUhalfEdge* eLast, GLUhalfEdge* eTopLeft,
|
|
GLboolean cleanUp)
|
|
{
|
|
ActiveRegion* reg;
|
|
ActiveRegion* regPrev;
|
|
GLUhalfEdge* e;
|
|
GLUhalfEdge* 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)
|
|
{
|
|
GLfloat 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;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Two vertices with idential coordinates are combined into one.
|
|
* e1->Org is kept, while e2->Org is discarded.
|
|
*/
|
|
static void SpliceMergeVertices(GLUtesselator* tess, GLUhalfEdge *e1, GLUhalfEdge* e2)
|
|
{
|
|
void* data[4]={NULL, NULL, NULL, NULL};
|
|
GLfloat weights[4]={0.5f, 0.5f, 0.0f, 0.0f};
|
|
|
|
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);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* 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".
|
|
*/
|
|
static void VertexWeights(GLUvertex* isect, GLUvertex* org, GLUvertex* dst,
|
|
GLfloat* weights)
|
|
{
|
|
GLfloat t1=VertL1dist(org, isect);
|
|
GLfloat t2=VertL1dist(dst, isect);
|
|
|
|
weights[0]=0.5f*t2/(t1+t2);
|
|
weights[1]=0.5f*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];
|
|
}
|
|
|
|
/*
|
|
* 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.
|
|
*/
|
|
static void GetIntersectData(GLUtesselator* tess, GLUvertex* isect,
|
|
GLUvertex* orgUp, GLUvertex* dstUp,
|
|
GLUvertex* orgLo, GLUvertex* dstLo)
|
|
{
|
|
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);
|
|
}
|
|
|
|
/*
|
|
* 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.
|
|
*/
|
|
static int CheckForRightSplice(GLUtesselator* tess, ActiveRegion* regUp)
|
|
{
|
|
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;
|
|
}
|
|
|
|
/*
|
|
* 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.
|
|
*/
|
|
static int CheckForLeftSplice(GLUtesselator* tess, ActiveRegion* regUp)
|
|
{
|
|
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;
|
|
}
|
|
|
|
/*
|
|
* 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.
|
|
*/
|
|
static int CheckForIntersect(GLUtesselator* tess, ActiveRegion* regUp)
|
|
{
|
|
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;
|
|
GLfloat tMinUp, tMaxLo;
|
|
GLUvertex isect;
|
|
GLUvertex* 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)
|
|
{
|
|
/* right endpoints are the same */
|
|
return FALSE;
|
|
}
|
|
|
|
tMinUp=MIN(orgUp->t, dstUp->t);
|
|
tMaxLo=MAX(orgLo->t, dstLo->t);
|
|
if (tMinUp>tMaxLo)
|
|
{
|
|
/* t ranges do not overlap */
|
|
return FALSE;
|
|
}
|
|
|
|
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;
|
|
}
|
|
|
|
/*
|
|
* 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.
|
|
*/
|
|
static void WalkDirtyRegions(GLUtesselator* tess, ActiveRegion* regUp)
|
|
{
|
|
ActiveRegion* regLo=RegionBelow(regUp);
|
|
GLUhalfEdge* eUp;
|
|
GLUhalfEdge* 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);
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* 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.
|
|
*/
|
|
static void ConnectRightVertex(GLUtesselator* tess, ActiveRegion* regUp,
|
|
GLUhalfEdge* eBottomLeft)
|
|
{
|
|
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
|
|
|
|
/*
|
|
* 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.
|
|
*/
|
|
static void ConnectLeftDegenerate(GLUtesselator* tess,
|
|
ActiveRegion* regUp, GLUvertex* vEvent)
|
|
{
|
|
GLUhalfEdge* e;
|
|
GLUhalfEdge* eTopLeft;
|
|
GLUhalfEdge* eTopRight;
|
|
GLUhalfEdge* 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);
|
|
}
|
|
|
|
/*
|
|
* 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
|
|
*/
|
|
static void ConnectLeftVertex(GLUtesselator* tess, GLUvertex* vEvent)
|
|
{
|
|
ActiveRegion* regUp;
|
|
ActiveRegion* regLo;
|
|
ActiveRegion* reg;
|
|
GLUhalfEdge* eUp;
|
|
GLUhalfEdge* eLo;
|
|
GLUhalfEdge* eNew;
|
|
ActiveRegion tmp;
|
|
|
|
/* 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);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Does everything necessary when the sweep line crosses a vertex.
|
|
* Updates the mesh and the edge dictionary.
|
|
*/
|
|
static void SweepEvent(GLUtesselator* tess, GLUvertex* vEvent)
|
|
{
|
|
ActiveRegion* regUp;
|
|
ActiveRegion* reg;
|
|
GLUhalfEdge* e;
|
|
GLUhalfEdge* eTopLeft;
|
|
GLUhalfEdge* 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 (4.0f*GLU_TESS_MAX_COORD)
|
|
|
|
/*
|
|
* We add two sentinel edges above and below all other edges,
|
|
* to avoid special cases at the top and bottom.
|
|
*/
|
|
static void AddSentinel(GLUtesselator* tess, GLfloat t)
|
|
{
|
|
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);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* We maintain an ordering of edge intersections with the sweep line.
|
|
* This order is maintained in a dynamic dictionary.
|
|
*/
|
|
static void InitEdgeDict(GLUtesselator* tess)
|
|
{
|
|
/* __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);
|
|
}
|
|
dictDeleteDict(tess->dict); /* __gl_dictListDeleteDict */
|
|
}
|
|
|
|
/*
|
|
* Remove zero-length edges, and contours with fewer than 3 vertices.
|
|
*/
|
|
static void RemoveDegenerateEdges(GLUtesselator* tess)
|
|
{
|
|
GLUhalfEdge* e;
|
|
GLUhalfEdge* eNext;
|
|
GLUhalfEdge* 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);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Insert all vertices into the priority queue which determines the
|
|
* order in which vertices cross the sweep line.
|
|
*/
|
|
static int InitPriorityQ(GLUtesselator* tess)
|
|
{
|
|
PriorityQ* pq;
|
|
GLUvertex* v;
|
|
GLUvertex* 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 */
|
|
}
|
|
|
|
/*
|
|
* 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.
|
|
*/
|
|
static int RemoveDegenerateFaces(GLUmesh* mesh)
|
|
{
|
|
GLUface* f;
|
|
GLUface* 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;
|
|
GLUvertex* 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;
|
|
}
|