public void testNeighbors()
{
Trace.WriteLine("TestNeighbors");
// Check the edge neighbors of face 1.
int[] outFaces = { 5, 3, 2, 0 };
var faceNbrs = S2CellId.FromFacePosLevel(1, 0, 0).GetEdgeNeighbors();
for (var i = 0; i < 4; ++i)
{
Assert.True(faceNbrs[i].IsFace);
JavaAssert.Equal(faceNbrs[i].Face, outFaces[i]);
}
// Check the vertex neighbors of the center of face 2 at level 5.
var nbrs = new List <S2CellId>();
S2CellId.FromPoint(new S2Point(0, 0, 1)).GetVertexNeighbors(5, nbrs);
nbrs.Sort();
for (var i = 0; i < 4; ++i)
{
JavaAssert.Equal(nbrs[i], S2CellId.FromFaceIj(
2, (1 << 29) - (i < 2 ? 1 : 0), (1 << 29) - ((i == 0 || i == 3) ? 1 : 0)).ParentForLevel(5));
}
nbrs.Clear();
// Check the vertex neighbors of the corner of faces 0, 4, and 5.
var id = S2CellId.FromFacePosLevel(0, 0, S2CellId.MaxLevel);
id.GetVertexNeighbors(0, nbrs);
nbrs.Sort();
JavaAssert.Equal(nbrs.Count, 3);
JavaAssert.Equal(nbrs[0], S2CellId.FromFacePosLevel(0, 0, 0));
JavaAssert.Equal(nbrs[1], S2CellId.FromFacePosLevel(4, 0, 0));
JavaAssert.Equal(nbrs[2], S2CellId.FromFacePosLevel(5, 0, 0));
// Check that GetAllNeighbors produces results that are consistent
// with GetVertexNeighbors for a bunch of random cells.
for (var i = 0; i < 1000; ++i)
{
var id1 = getRandomCellId();
var toTest = id1;
if (id1.IsLeaf)
{
toTest = id1.Parent;
}
// TestAllNeighbors computes approximately 2**(2*(diff+1)) cell id1s,
// so it's not reasonable to use large values of "diff".
var maxDiff = Math.Min(6, S2CellId.MaxLevel - toTest.Level - 1);
var level = toTest.Level + random(maxDiff);
testAllNeighbors(toTest, level);
}
}