jogamp.opengl.glu.tessellator.Sweep Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of jogl-all Show documentation
Show all versions of jogl-all Show documentation
Java™ Binding for the OpenGL® API
/*
* Portions Copyright (C) 2003-2006 Sun Microsystems, Inc.
* All rights reserved.
*/
/*
** 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 2.0 (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.
**
** NOTE: The Original Code (as defined below) has been licensed to Sun
** Microsystems, Inc. ("Sun") under the SGI Free Software License B
** (Version 1.1), shown above ("SGI License"). Pursuant to Section
** 3.2(3) of the SGI License, Sun is distributing the Covered Code to
** you under an alternative license ("Alternative License"). This
** Alternative License includes all of the provisions of the SGI License
** except that Section 2.2 and 11 are omitted. Any differences between
** the Alternative License and the SGI License are offered solely by Sun
** and not by SGI.
**
** 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
** Java Port: Pepijn Van Eeckhoudt, July 2003
** Java Port: Nathan Parker Burg, August 2003
*/
package jogamp.opengl.glu.tessellator;
import javax.media.opengl.*;
import javax.media.opengl.glu.*;
class Sweep {
private Sweep() {
}
// #ifdef FOR_TRITE_TEST_PROGRAM
// extern void DebugEvent( GLUtessellator *tess );
// #else
private static void DebugEvent(GLUtessellatorImpl 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.)
*/
/* When we merge two edges into one, we need to compute the combined
* winding of the new edge.
*/
private static void AddWinding(GLUhalfEdge eDst, GLUhalfEdge eSrc) {
eDst.winding += eSrc.winding;
eDst.Sym.winding += eSrc.Sym.winding;
}
private static ActiveRegion RegionBelow(ActiveRegion r) {
return ((ActiveRegion) Dict.dictKey(Dict.dictPred(r.nodeUp)));
}
private static ActiveRegion RegionAbove(ActiveRegion r) {
return ((ActiveRegion) Dict.dictKey(Dict.dictSucc(r.nodeUp)));
}
static boolean EdgeLeq(GLUtessellatorImpl 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;
double t1, t2;
e1 = reg1.eUp;
e2 = reg2.eUp;
if (e1.Sym.Org == event) {
if (e2.Sym.Org == event) {
/* Two edges right of the sweep line which meet at the sweep event.
* Sort them by slope.
*/
if (Geom.VertLeq(e1.Org, e2.Org)) {
return Geom.EdgeSign(e2.Sym.Org, e1.Org, e2.Org) <= 0;
}
return Geom.EdgeSign(e1.Sym.Org, e2.Org, e1.Org) >= 0;
}
return Geom.EdgeSign(e2.Sym.Org, event, e2.Org) <= 0;
}
if (e2.Sym.Org == event) {
return Geom.EdgeSign(e1.Sym.Org, event, e1.Org) >= 0;
}
/* General case - compute signed distance *from* e1, e2 to event */
t1 = Geom.EdgeEval(e1.Sym.Org, event, e1.Org);
t2 = Geom.EdgeEval(e2.Sym.Org, event, e2.Org);
return (t1 >= t2);
}
static void DeleteRegion(GLUtessellatorImpl 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;
Dict.dictDelete(tess.dict, reg.nodeUp); /* __gl_dictListDelete */
}
static boolean FixUpperEdge(ActiveRegion reg, GLUhalfEdge newEdge)
/*
* Replace an upper edge which needs fixing (see ConnectRightVertex).
*/ {
assert (reg.fixUpperEdge);
if (!Mesh.__gl_meshDelete(reg.eUp)) return false;
reg.fixUpperEdge = false;
reg.eUp = newEdge;
newEdge.activeRegion = reg;
return true;
}
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 = Mesh.__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.Sym.Org;
/* Find the region above the uppermost edge with the same destination */
do {
reg = RegionAbove(reg);
} while (reg.eUp.Sym.Org == dst);
return reg;
}
static ActiveRegion AddRegionBelow(GLUtessellatorImpl 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 = new ActiveRegion();
if (regNew == null) throw new RuntimeException();
regNew.eUp = eNewUp;
/* __gl_dictListInsertBefore */
regNew.nodeUp = Dict.dictInsertBefore(tess.dict, regAbove.nodeUp, regNew);
if (regNew.nodeUp == null) throw new RuntimeException();
regNew.fixUpperEdge = false;
regNew.sentinel = false;
regNew.dirty = false;
eNewUp.activeRegion = regNew;
return regNew;
}
static boolean IsWindingInside(GLUtessellatorImpl tess, int n) {
switch (tess.windingRule) {
case GLU.GLU_TESS_WINDING_ODD:
return (n & 1) != 0;
case GLU.GLU_TESS_WINDING_NONZERO:
return (n != 0);
case GLU.GLU_TESS_WINDING_POSITIVE:
return (n > 0);
case GLU.GLU_TESS_WINDING_NEGATIVE:
return (n < 0);
case GLU.GLU_TESS_WINDING_ABS_GEQ_TWO:
return (n >= 2) || (n <= -2);
}
/*LINTED*/
// assert (false);
throw new InternalError();
/*NOTREACHED*/
}
static void ComputeWinding(GLUtessellatorImpl tess, ActiveRegion reg) {
reg.windingNumber = RegionAbove(reg).windingNumber + reg.eUp.winding;
reg.inside = IsWindingInside(tess, reg.windingNumber);
}
static void FinishRegion(GLUtessellatorImpl 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(GLUtessellatorImpl 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 = Mesh.__gl_meshConnect(ePrev.Onext.Sym, e.Sym);
if (e == null) throw new RuntimeException();
if (!FixUpperEdge(reg, e)) throw new RuntimeException();
}
/* Relink edges so that ePrev.Onext == e */
if (ePrev.Onext != e) {
if (!Mesh.__gl_meshSplice(e.Sym.Lnext, e)) throw new RuntimeException();
if (!Mesh.__gl_meshSplice(ePrev, e)) throw new RuntimeException();
}
FinishRegion(tess, regPrev); /* may change reg.eUp */
ePrev = reg.eUp;
regPrev = reg;
}
return ePrev;
}
static void AddRightEdges(GLUtessellatorImpl tess, ActiveRegion regUp,
GLUhalfEdge eFirst, GLUhalfEdge eLast, GLUhalfEdge eTopLeft,
boolean 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.Sym.Lnext. 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.Sym.Lnext and eTopLeft; otherwise eTopLeft
* should be null.
*/ {
ActiveRegion reg, regPrev;
GLUhalfEdge e, ePrev;
boolean firstTime = true;
/* Insert the new right-going edges in the dictionary */
e = eFirst;
do {
assert (Geom.VertLeq(e.Org, e.Sym.Org));
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.Sym.Onext;
}
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 (!Mesh.__gl_meshSplice(e.Sym.Lnext, e)) throw new RuntimeException();
if (!Mesh.__gl_meshSplice(ePrev.Sym.Lnext, e)) throw new RuntimeException();
}
/* 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 (!Mesh.__gl_meshDelete(ePrev)) throw new RuntimeException();
}
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(GLUtessellatorImpl tess, GLUvertex isect,
Object[] data, float[] weights, boolean needed) {
double[] coords = new double[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];
Object[] outData = new Object[1];
tess.callCombineOrCombineData(coords, data, weights, outData);
isect.data = outData[0];
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.
*/
tess.callErrorOrErrorData(GLU.GLU_TESS_NEED_COMBINE_CALLBACK);
tess.fatalError = true;
}
}
}
static void SpliceMergeVertices(GLUtessellatorImpl tess, GLUhalfEdge e1,
GLUhalfEdge e2)
/*
* Two vertices with idential coordinates are combined into one.
* e1.Org is kept, while e2.Org is discarded.
*/ {
Object[] data = new Object[4];
float[] weights = new float[]{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 (!Mesh.__gl_meshSplice(e1, e2)) throw new RuntimeException();
}
static void VertexWeights(GLUvertex isect, GLUvertex org, GLUvertex dst,
float[] 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".
*/ {
double t1 = Geom.VertL1dist(org, isect);
double t2 = Geom.VertL1dist(dst, isect);
weights[0] = (float) (0.5 * t2 / (t1 + t2));
weights[1] = (float) (0.5 * t1 / (t1 + t2));
isect.coords[0] += weights[0] * org.coords[0] + weights[1] * dst.coords[0];
isect.coords[1] += weights[0] * org.coords[1] + weights[1] * dst.coords[1];
isect.coords[2] += weights[0] * org.coords[2] + weights[1] * dst.coords[2];
}
static void GetIntersectData(GLUtessellatorImpl 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.
*/ {
Object[] data = new Object[4];
float[] weights = new float[4];
float[] weights1 = new float[2];
float[] weights2 = new float[2];
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, weights1);
VertexWeights(isect, orgLo, dstLo, weights2);
System.arraycopy(weights1, 0, weights, 0, 2);
System.arraycopy(weights2, 0, weights, 2, 2);
CallCombine(tess, isect, data, weights, true);
}
static boolean CheckForRightSplice(GLUtessellatorImpl 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 (Geom.VertLeq(eUp.Org, eLo.Org)) {
if (Geom.EdgeSign(eLo.Sym.Org, eUp.Org, eLo.Org) > 0) return false;
/* eUp.Org appears to be below eLo */
if (!Geom.VertEq(eUp.Org, eLo.Org)) {
/* Splice eUp.Org into eLo */
if (Mesh.__gl_meshSplitEdge(eLo.Sym) == null) throw new RuntimeException();
if (!Mesh.__gl_meshSplice(eUp, eLo.Sym.Lnext)) throw new RuntimeException();
regUp.dirty = regLo.dirty = true;
} else if (eUp.Org != eLo.Org) {
/* merge the two vertices, discarding eUp.Org */
tess.pq.pqDelete(eUp.Org.pqHandle); /* __gl_pqSortDelete */
SpliceMergeVertices(tess, eLo.Sym.Lnext, eUp);
}
} else {
if (Geom.EdgeSign(eUp.Sym.Org, 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 (Mesh.__gl_meshSplitEdge(eUp.Sym) == null) throw new RuntimeException();
if (!Mesh.__gl_meshSplice(eLo.Sym.Lnext, eUp)) throw new RuntimeException();
}
return true;
}
static boolean CheckForLeftSplice(GLUtessellatorImpl tess, ActiveRegion regUp)
/*
* Check the upper and lower edge of "regUp", to make sure that the
* eUp.Sym.Org is above eLo, or eLo.Sym.Org 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.Sym.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
* the test so that now eUp.Sym.Org 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 (!Geom.VertEq(eUp.Sym.Org, eLo.Sym.Org));
if (Geom.VertLeq(eUp.Sym.Org, eLo.Sym.Org)) {
if (Geom.EdgeSign(eUp.Sym.Org, eLo.Sym.Org, eUp.Org) < 0) return false;
/* eLo.Sym.Org is above eUp, so splice eLo.Sym.Org into eUp */
RegionAbove(regUp).dirty = regUp.dirty = true;
e = Mesh.__gl_meshSplitEdge(eUp);
if (e == null) throw new RuntimeException();
if (!Mesh.__gl_meshSplice(eLo.Sym, e)) throw new RuntimeException();
e.Lface.inside = regUp.inside;
} else {
if (Geom.EdgeSign(eLo.Sym.Org, eUp.Sym.Org, eLo.Org) > 0) return false;
/* eUp.Sym.Org is below eLo, so splice eUp.Sym.Org into eLo */
regUp.dirty = regLo.dirty = true;
e = Mesh.__gl_meshSplitEdge(eLo);
if (e == null) throw new RuntimeException();
if (!Mesh.__gl_meshSplice(eUp.Lnext, eLo.Sym)) throw new RuntimeException();
e.Sym.Lface.inside = regUp.inside;
}
return true;
}
static boolean CheckForIntersect(GLUtessellatorImpl 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.Sym.Org;
GLUvertex dstLo = eLo.Sym.Org;
double tMinUp, tMaxLo;
GLUvertex isect = new GLUvertex();
GLUvertex orgMin;
GLUhalfEdge e;
assert (!Geom.VertEq(dstLo, dstUp));
assert (Geom.EdgeSign(dstUp, tess.event, orgUp) <= 0);
assert (Geom.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 = Math.min(orgUp.t, dstUp.t);
tMaxLo = Math.max(orgLo.t, dstLo.t);
if (tMinUp > tMaxLo) return false; /* t ranges do not overlap */
if (Geom.VertLeq(orgUp, orgLo)) {
if (Geom.EdgeSign(dstLo, orgUp, orgLo) > 0) return false;
} else {
if (Geom.EdgeSign(dstUp, orgLo, orgUp) < 0) return false;
}
/* At this point the edges intersect, at least marginally */
DebugEvent(tess);
Geom.EdgeIntersect(dstUp, orgUp, dstLo, orgLo, isect);
/* The following properties are guaranteed: */
assert (Math.min(orgUp.t, dstUp.t) <= isect.t);
assert (isect.t <= Math.max(orgLo.t, dstLo.t));
assert (Math.min(dstLo.s, dstUp.s) <= isect.s);
assert (isect.s <= Math.max(orgLo.s, orgUp.s));
if (Geom.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 = Geom.VertLeq(orgUp, orgLo) ? orgUp : orgLo;
if (Geom.VertLeq(orgMin, isect)) {
isect.s = orgMin.s;
isect.t = orgMin.t;
}
if (Geom.VertEq(isect, orgUp) || Geom.VertEq(isect, orgLo)) {
/* Easy case -- intersection at one of the right endpoints */
CheckForRightSplice(tess, regUp);
return false;
}
if ((!Geom.VertEq(dstUp, tess.event)
&& Geom.EdgeSign(dstUp, tess.event, isect) >= 0)
|| (!Geom.VertEq(dstLo, tess.event)
&& Geom.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 (Mesh.__gl_meshSplitEdge(eUp.Sym) == null) throw new RuntimeException();
if (!Mesh.__gl_meshSplice(eLo.Sym, eUp)) throw new RuntimeException();
regUp = TopLeftRegion(regUp);
if (regUp == null) throw new RuntimeException();
eUp = RegionBelow(regUp).eUp;
FinishLeftRegions(tess, RegionBelow(regUp), regLo);
AddRightEdges(tess, regUp, eUp.Sym.Lnext, eUp, eUp, true);
return true;
}
if (dstUp == tess.event) {
/* Splice dstUp into eLo, and process the new region(s) */
if (Mesh.__gl_meshSplitEdge(eLo.Sym) == null) throw new RuntimeException();
if (!Mesh.__gl_meshSplice(eUp.Lnext, eLo.Sym.Lnext)) throw new RuntimeException();
regLo = regUp;
regUp = TopRightRegion(regUp);
e = RegionBelow(regUp).eUp.Sym.Onext;
regLo.eUp = eLo.Sym.Lnext;
eLo = FinishLeftRegions(tess, regLo, null);
AddRightEdges(tess, regUp, eLo.Onext, eUp.Sym.Onext, 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 (Geom.EdgeSign(dstUp, tess.event, isect) >= 0) {
RegionAbove(regUp).dirty = regUp.dirty = true;
if (Mesh.__gl_meshSplitEdge(eUp.Sym) == null) throw new RuntimeException();
eUp.Org.s = tess.event.s;
eUp.Org.t = tess.event.t;
}
if (Geom.EdgeSign(dstLo, tess.event, isect) <= 0) {
regUp.dirty = regLo.dirty = true;
if (Mesh.__gl_meshSplitEdge(eLo.Sym) == null) throw new RuntimeException();
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.Sym.Lnext.Lface).
*/
if (Mesh.__gl_meshSplitEdge(eUp.Sym) == null) throw new RuntimeException();
if (Mesh.__gl_meshSplitEdge(eLo.Sym) == null) throw new RuntimeException();
if (!Mesh.__gl_meshSplice(eLo.Sym.Lnext, eUp)) throw new RuntimeException();
eUp.Org.s = isect.s;
eUp.Org.t = isect.t;
eUp.Org.pqHandle = tess.pq.pqInsert(eUp.Org); /* __gl_pqSortInsert */
if (eUp.Org.pqHandle == Long.MAX_VALUE) {
tess.pq.pqDeletePriorityQ(); /* __gl_pqSortDeletePriorityQ */
tess.pq = null;
throw new RuntimeException();
}
GetIntersectData(tess, eUp.Org, orgUp, dstUp, orgLo, dstLo);
RegionAbove(regUp).dirty = regUp.dirty = regLo.dirty = true;
return false;
}
static void WalkDirtyRegions(GLUtessellatorImpl 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.Sym.Org != eLo.Sym.Org) {
/* 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 (!Mesh.__gl_meshDelete(eLo)) throw new RuntimeException();
regLo = RegionBelow(regUp);
eLo = regLo.eUp;
} else if (regUp.fixUpperEdge) {
DeleteRegion(tess, regUp);
if (!Mesh.__gl_meshDelete(eUp)) throw new RuntimeException();
regUp = RegionAbove(regLo);
eUp = regUp.eUp;
}
}
}
if (eUp.Org != eLo.Org) {
if (eUp.Sym.Org != eLo.Sym.Org
&& !regUp.fixUpperEdge && !regLo.fixUpperEdge
&& (eUp.Sym.Org == tess.event || eLo.Sym.Org == 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.
*/
CheckForRightSplice(tess, regUp);
}
}
if (eUp.Org == eLo.Org && eUp.Sym.Org == eLo.Sym.Org) {
/* A degenerate loop consisting of only two edges -- delete it. */
AddWinding(eLo, eUp);
DeleteRegion(tess, regUp);
if (!Mesh.__gl_meshDelete(eUp)) throw new RuntimeException();
regUp = RegionAbove(regLo);
}
}
}
static void ConnectRightVertex(GLUtessellatorImpl 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;
boolean degenerate = false;
if (eUp.Sym.Org != eLo.Sym.Org) {
CheckForIntersect(tess, regUp);
}
/* Possible new degeneracies: upper or lower edge of regUp may pass
* through vEvent, or may coincide with new intersection vertex
*/
if (Geom.VertEq(eUp.Org, tess.event)) {
if (!Mesh.__gl_meshSplice(eTopLeft.Sym.Lnext, eUp)) throw new RuntimeException();
regUp = TopLeftRegion(regUp);
if (regUp == null) throw new RuntimeException();
eTopLeft = RegionBelow(regUp).eUp;
FinishLeftRegions(tess, RegionBelow(regUp), regLo);
degenerate = true;
}
if (Geom.VertEq(eLo.Org, tess.event)) {
if (!Mesh.__gl_meshSplice(eBottomLeft, eLo.Sym.Lnext)) throw new RuntimeException();
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 (Geom.VertLeq(eLo.Org, eUp.Org)) {
eNew = eLo.Sym.Lnext;
} else {
eNew = eUp;
}
eNew = Mesh.__gl_meshConnect(eBottomLeft.Onext.Sym, eNew);
if (eNew == null) throw new RuntimeException();
/* 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.
*/
private static final boolean TOLERANCE_NONZERO = false;
static void ConnectLeftDegenerate(GLUtessellatorImpl 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 (Geom.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 (!Geom.VertEq(e.Sym.Org, vEvent)) {
/* General case -- splice vEvent into edge e which passes through it */
if (Mesh.__gl_meshSplitEdge(e.Sym) == null) throw new RuntimeException();
if (regUp.fixUpperEdge) {
/* This edge was fixable -- delete unused portion of original edge */
if (!Mesh.__gl_meshDelete(e.Onext)) throw new RuntimeException();
regUp.fixUpperEdge = false;
}
if (!Mesh.__gl_meshSplice(vEvent.anEdge, e)) throw new RuntimeException();
SweepEvent(tess, vEvent); /* recurse */
return;
}
/* vEvent coincides with e.Sym.Org, 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.Sym.Org 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 (!Mesh.__gl_meshDelete(eTopRight)) throw new RuntimeException();
eTopRight = eTopLeft.Sym.Lnext;
}
if (!Mesh.__gl_meshSplice(vEvent.anEdge, eTopRight)) throw new RuntimeException();
if (!Geom.EdgeGoesLeft(eTopLeft)) {
/* e.Sym.Org had no left-going edges -- indicate this to AddRightEdges() */
eTopLeft = null;
}
AddRightEdges(tess, regUp, eTopRight.Onext, eLast, eTopLeft, true);
}
static void ConnectLeftVertex(GLUtessellatorImpl 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 = new ActiveRegion();
/* 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) Dict.dictKey(Dict.dictSearch(tess.dict, tmp));
regLo = RegionBelow(regUp);
eUp = regUp.eUp;
eLo = regLo.eUp;
/* Try merging with U or L first */
if (Geom.EdgeSign(eUp.Sym.Org, vEvent, eUp.Org) == 0) {
ConnectLeftDegenerate(tess, regUp, vEvent);
return;
}
/* Connect vEvent to rightmost processed vertex of either chain.
* e.Sym.Org is the vertex that we will connect to vEvent.
*/
reg = Geom.VertLeq(eLo.Sym.Org, eUp.Sym.Org) ? regUp : regLo;
if (regUp.inside || reg.fixUpperEdge) {
if (reg == regUp) {
eNew = Mesh.__gl_meshConnect(vEvent.anEdge.Sym, eUp.Lnext);
if (eNew == null) throw new RuntimeException();
} else {
GLUhalfEdge tempHalfEdge = Mesh.__gl_meshConnect(eLo.Sym.Onext.Sym, vEvent.anEdge);
if (tempHalfEdge == null) throw new RuntimeException();
eNew = tempHalfEdge.Sym;
}
if (reg.fixUpperEdge) {
if (!FixUpperEdge(reg, eNew)) throw new RuntimeException();
} 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(GLUtessellatorImpl 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) throw new RuntimeException();
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).
*/
private static final double SENTINEL_COORD = (4.0 * GLU.GLU_TESS_MAX_COORD);
static void AddSentinel(GLUtessellatorImpl tess, double 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 = new ActiveRegion();
if (reg == null) throw new RuntimeException();
e = Mesh.__gl_meshMakeEdge(tess.mesh);
if (e == null) throw new RuntimeException();
e.Org.s = SENTINEL_COORD;
e.Org.t = t;
e.Sym.Org.s = -SENTINEL_COORD;
e.Sym.Org.t = t;
tess.event = e.Sym.Org; /* initialize it */
reg.eUp = e;
reg.windingNumber = 0;
reg.inside = false;
reg.fixUpperEdge = false;
reg.sentinel = true;
reg.dirty = false;
reg.nodeUp = Dict.dictInsert(tess.dict, reg); /* __gl_dictListInsertBefore */
if (reg.nodeUp == null) throw new RuntimeException();
}
static void InitEdgeDict(final GLUtessellatorImpl tess)
/*
* We maintain an ordering of edge intersections with the sweep line.
* This order is maintained in a dynamic dictionary.
*/ {
/* __gl_dictListNewDict */
tess.dict = Dict.dictNewDict(tess, new Dict.DictLeq() {
public boolean leq(Object frame, Object key1, Object key2) {
return EdgeLeq(tess, (ActiveRegion) key1, (ActiveRegion) key2);
}
});
if (tess.dict == null) throw new RuntimeException();
AddSentinel(tess, -SENTINEL_COORD);
AddSentinel(tess, SENTINEL_COORD);
}
static void DoneEdgeDict(GLUtessellatorImpl tess) {
ActiveRegion reg;
int fixedEdges = 0;
/* __GL_DICTLISTKEY */ /* __GL_DICTLISTMIN */
while ((reg = (ActiveRegion) Dict.dictKey(Dict.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 );*/
}
Dict.dictDeleteDict(tess.dict); /* __gl_dictListDeleteDict */
}
static void RemoveDegenerateEdges(GLUtessellatorImpl 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 (Geom.VertEq(e.Org, e.Sym.Org) && e.Lnext.Lnext != e) {
/* Zero-length edge, contour has at least 3 edges */
SpliceMergeVertices(tess, eLnext, e); /* deletes e.Org */
if (!Mesh.__gl_meshDelete(e)) throw new RuntimeException(); /* 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 (!Mesh.__gl_meshDelete(eLnext)) throw new RuntimeException();
}
if (e == eNext || e == eNext.Sym) {
eNext = eNext.next;
}
if (!Mesh.__gl_meshDelete(e)) throw new RuntimeException();
}
}
}
static boolean InitPriorityQ(GLUtessellatorImpl 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 = PriorityQ.pqNewPriorityQ(new PriorityQ.Leq() {
public boolean leq(Object key1, Object key2) {
return Geom.VertLeq(((GLUvertex) key1), (GLUvertex) key2);
}
});
if (pq == null) return false;
vHead = tess.mesh.vHead;
for (v = vHead.next; v != vHead; v = v.next) {
v.pqHandle = pq.pqInsert(v); /* __gl_pqSortInsert */
if (v.pqHandle == Long.MAX_VALUE) break;
}
if (v != vHead || !pq.pqInit()) { /* __gl_pqSortInit */
tess.pq.pqDeletePriorityQ(); /* __gl_pqSortDeletePriorityQ */
tess.pq = null;
return false;
}
return true;
}
static void DonePriorityQ(GLUtessellatorImpl tess) {
tess.pq.pqDeletePriorityQ(); /* __gl_pqSortDeletePriorityQ */
}
static boolean 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 (!Mesh.__gl_meshDelete(e)) return false;
}
}
return true;
}
public static boolean __gl_computeInterior(GLUtessellatorImpl 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 false; /* if error */
InitEdgeDict(tess);
/* __gl_pqSortExtractMin */
while ((v = (GLUvertex) tess.pq.pqExtractMin()) != null) {
for (; ;) {
vNext = (GLUvertex) tess.pq.pqMinimum(); /* __gl_pqSortMinimum */
if (vNext == null || !Geom.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) tess.pq.pqExtractMin(); /* __gl_pqSortExtractMin*/
SpliceMergeVertices(tess, v.anEdge, vNext.anEdge);
}
SweepEvent(tess, v);
}
/* Set tess.event for debugging purposes */
/* __GL_DICTLISTKEY */ /* __GL_DICTLISTMIN */
tess.event = ((ActiveRegion) Dict.dictKey(Dict.dictMin(tess.dict))).eUp.Org;
DebugEvent(tess);
DoneEdgeDict(tess);
DonePriorityQ(tess);
if (!RemoveDegenerateFaces(tess.mesh)) return false;
Mesh.__gl_meshCheckMesh(tess.mesh);
return true;
}
}