public void Test_GetReferencePoint_PartiallyDegenerateLoops()
{
for (var iter = 0; iter < 100; ++iter)
{
// First we construct a long convoluted edge chain that follows the
// S2CellId Hilbert curve. At some random point along the curve, we
// insert a small triangular loop.
List <List <S2Point> > loops = new(1) { new() };
var loop = loops[0];
int num_vertices = 100;
var start = S2Testing.GetRandomCellId(S2.kMaxCellLevel - 1);
var end = start.AdvanceWrap(num_vertices);
var loop_cellid = start.AdvanceWrap(
S2Testing.Random.Uniform(num_vertices - 2) + 1);
var triangle = new List <S2Point>();
for (var cellid = start; cellid != end; cellid = cellid.NextWrap())
{
if (cellid == loop_cellid)
{
// Insert a small triangular loop. We save the loop so that we can
// test whether it contains the origin later.
triangle.Add(cellid.Child(0).ToPoint());
triangle.Add(cellid.Child(1).ToPoint());
triangle.Add(cellid.Child(2).ToPoint());
loop.AddRange(triangle);
loop.Add(cellid.Child(0).ToPoint());
}
else
{
loop.Add(cellid.ToPoint());
}
}
// Now we retrace our steps, except that we skip the three edges that form
// the triangular loop above.
for (S2CellId cellid = end; cellid != start; cellid = cellid.PrevWrap())
{
if (cellid == loop_cellid)
{
loop.Add(cellid.Child(0).ToPoint());
}
else
{
loop.Add(cellid.ToPoint());
}
}
S2LaxPolygonShape shape = new(loops);
S2Loop triangle_loop = new(triangle);
var rp = shape.GetReferencePoint();
Assert.Equal(triangle_loop.Contains(rp.Point), rp.Contained);
}
}
}