private static bool flipTriangle(List <Point> points, List <Triad> triads, int testInd, out int flipInd)
{
int opp = 0, e1, e2, e3 = 0, e4 = 0;
flipInd = 0;
Triad t = triads[testInd];
if (t.bc >= 0)
{
flipInd = t.bc;
Triad t2 = triads[flipInd];
t2.findAdj(t.b, testInd, out opp, out e3, out e4);
if (t.insideCircumcircle(points[opp]))
{
e1 = t.ab;
e2 = t.ac;
if (e1 != e3 && e2 != e4)
{
int ta = t.a, tb = t.b, tc = t.c;
t.init(ta, tb, opp, e1, e3, flipInd, points);
t2.init(ta, tc, opp, e2, e4, testInd, points);
if (e3 >= 0)
{
triads[e3].changeAdjInd(flipInd, testInd);
}
if (e2 >= 0)
{
triads[e2].changeAdjInd(testInd, flipInd);
}
return(true);
}
}
}
if (t.ab >= 0)
{
flipInd = t.ab;
Triad t2 = triads[flipInd];
t2.findAdj(t.a, testInd, out opp, out e3, out e4);
if (t.insideCircumcircle(points[opp]))
{
e1 = t.ac;
e2 = t.bc;
if (e1 != e3 && e2 != e4)
{
int ta = t.a, tb = t.b, tc = t.c;
t.init(tc, ta, opp, e1, e3, flipInd, points);
t2.init(tc, tb, opp, e2, e4, testInd, points);
if (e3 >= 0)
{
triads[e3].changeAdjInd(flipInd, testInd);
}
if (e2 >= 0)
{
triads[e2].changeAdjInd(testInd, flipInd);
}
return(true);
}
}
}
if (t.ac >= 0)
{
flipInd = t.ac;
Triad t2 = triads[flipInd];
t2.findAdj(t.a, testInd, out opp, out e3, out e4);
if (t.insideCircumcircle(points[opp]))
{
e1 = t.ab;
e2 = t.bc;
if (e1 != e3 && e2 != e4)
{
int ta = t.a, tb = t.b, tc = t.c;
t.init(tb, ta, opp, e1, e3, flipInd, points);
t2.init(tb, tc, opp, e2, e4, testInd, points);
if (e3 >= 0)
{
triads[e3].changeAdjInd(flipInd, testInd);
}
if (e2 >= 0)
{
triads[e2].changeAdjInd(testInd, flipInd);
}
return(true);
}
}
}
return(false);
}