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/*
* Copyright (c) 2007 Sun Microsystems, Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* - Redistribution of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* - Redistribution in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* Neither the name of Sun Microsystems, Inc. or the names of
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* This software is provided "AS IS," without a warranty of any
* kind. ALL EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND
* WARRANTIES, INCLUDING ANY IMPLIED WARRANTY OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT, ARE HEREBY
* EXCLUDED. SUN MICROSYSTEMS, INC. ("SUN") AND ITS LICENSORS SHALL
* NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF
* USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS
* DERIVATIVES. IN NO EVENT WILL SUN OR ITS LICENSORS BE LIABLE FOR
* ANY LOST REVENUE, PROFIT OR DATA, OR FOR DIRECT, INDIRECT, SPECIAL,
* CONSEQUENTIAL, INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER CAUSED AND
* REGARDLESS OF THE THEORY OF LIABILITY, ARISING OUT OF THE USE OF OR
* INABILITY TO USE THIS SOFTWARE, EVEN IF SUN HAS BEEN ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGES.
*
* You acknowledge that this software is not designed, licensed or
* intended for use in the design, construction, operation or
* maintenance of any nuclear facility.
*
*/
// ----------------------------------------------------------------------
//
// The reference to Fast Industrial Strength Triangulation (FIST) code
// in this release by Sun Microsystems is related to Sun's rewrite of
// an early version of FIST. FIST was originally created by Martin
// Held and Joseph Mitchell at Stony Brook University and is
// incorporated by Sun under an agreement with The Research Foundation
// of SUNY (RFSUNY). The current version of FIST is available for
// commercial use under a license agreement with RFSUNY on behalf of
// the authors and Stony Brook University. Please contact the Office
// of Technology Licensing at Stony Brook, phone 631-632-9009, for
// licensing information.
//
// ----------------------------------------------------------------------
package com.sun.j3d.utils.geometry;
class Degenerate {
/**
* This function checks whether the triangle i1, i2, i3 is an ear, where
* the vertex i4 lies on at least one of the two edges i1, i2 or i3, i1.
* basically, we can cut the polygon at i4 into two pieces. the polygon
* touches at i4 back to back if following the next-pointers in one
* subpolygon and following the prev-pointers in the other subpolygon yields
* the same orientation for both subpolygons. otherwise, i4 forms a
* bottle neck of the polygon, and i1, i2, i3 is no valid ear.
*
* Note that this function may come up with the incorrect answer if the
* polygon has self-intersections.
*/
static boolean handleDegeneracies(Triangulator triRef, int i1, int ind1, int i2,
int i3, int i4, int ind4) {
int i0, i5;
int type[] = new int[1];
int ind0, ind2, ind5;
boolean flag;
double area = 0.0, area1 = 0, area2 = 0.0;
/* assert(InPointsList(i1));
assert(InPointsList(i2));
assert(InPointsList(i3));
assert(InPointsList(i4));
*/
// first check whether the successor or predecessor of i4 is inside the
// triangle, or whether any of the two edges incident at i4 intersects
// i2, i3.
ind5 = triRef.fetchPrevData(ind4);
i5 = triRef.fetchData(ind5);
// assert(ind4 != ind5);
//assert(InPointsList(i5));
if ((i5 != i2) && (i5 != i3)) {
flag = Numerics.vtxInTriangle(triRef, i1, i2, i3, i5, type);
if (flag && (type[0] == 0)) return true;
if (i2 <= i3) {
if (i4 <= i5)
flag = Numerics.segIntersect(triRef, i2, i3, i4, i5, -1);
else
flag = Numerics.segIntersect(triRef, i2, i3, i5, i4, -1);
}
else {
if (i4 <= i5)
flag = Numerics.segIntersect(triRef, i3, i2, i4, i5, -1);
else
flag = Numerics.segIntersect(triRef, i3, i2, i5, i4, -1);
}
if (flag)
return true;
}
ind5 = triRef.fetchNextData(ind4);
i5 = triRef.fetchData(ind5);
// assert(ind4 != ind5);
// assert(InPointsList(i5));
if ((i5 != i2) && (i5 != i3)) {
flag = Numerics.vtxInTriangle(triRef, i1, i2, i3, i5, type);
if (flag && (type[0] == 0)) return true;
if (i2 <= i3) {
if (i4 <= i5) flag = Numerics.segIntersect(triRef, i2, i3, i4, i5, -1);
else flag = Numerics.segIntersect(triRef, i2, i3, i5, i4, -1);
}
else {
if (i4 <= i5) flag = Numerics.segIntersect(triRef, i3, i2, i4, i5, -1);
else flag = Numerics.segIntersect(triRef, i3, i2, i5, i4, -1);
}
if (flag) return true;
}
i0 = i1;
ind0 = ind1;
ind1 = triRef.fetchNextData(ind1);
i1 = triRef.fetchData(ind1);
while (ind1 != ind4) {
ind2 = triRef.fetchNextData(ind1);
i2 = triRef.fetchData(ind2);
area = Numerics.stableDet2D(triRef, i0, i1, i2);
area1 += area;
ind1 = ind2;
i1 = i2;
}
ind1 = triRef.fetchPrevData(ind0);
i1 = triRef.fetchData(ind1);
while (ind1 != ind4) {
ind2 = triRef.fetchPrevData(ind1);
i2 = triRef.fetchData(ind2);
area = Numerics.stableDet2D(triRef, i0, i1, i2);
area2 += area;
ind1 = ind2;
i1 = i2;
}
if (Numerics.le(area1, triRef.ZERO) && Numerics.le(area2, triRef.ZERO))
return false;
else if (Numerics.ge(area1, triRef.ZERO) && Numerics.ge(area2, triRef.ZERO))
return false;
else
return true;
}
}