public void Test_S2PaddedCell_GetEntryExitVertices()
{
int kIters = 1000;
for (int iter = 0; iter < kIters; ++iter)
{
S2CellId id = S2Testing.GetRandomCellId();
// Check that entry/exit vertices do not depend on padding.
Assert.Equal(new S2PaddedCell(id, 0).GetEntryVertex(),
new S2PaddedCell(id, 0.5).GetEntryVertex());
Assert.Equal(new S2PaddedCell(id, 0).GetExitVertex(),
new S2PaddedCell(id, 0.5).GetExitVertex());
// Check that the exit vertex of one cell is the same as the entry vertex
// of the immediately following cell. (This also tests wrapping from the
// end to the start of the S2CellId curve with high probability.)
Assert.Equal(new S2PaddedCell(id, 0).GetExitVertex(),
new S2PaddedCell(id.NextWrap(), 0).GetEntryVertex());
// Check that the entry vertex of a cell is the same as the entry vertex
// of its first child, and similarly for the exit vertex.
if (!id.IsLeaf())
{
Assert.Equal(new S2PaddedCell(id, 0).GetEntryVertex(),
new S2PaddedCell(id.Child(0), 0).GetEntryVertex());
Assert.Equal(new S2PaddedCell(id, 0).GetExitVertex(),
new S2PaddedCell(id.Child(3), 0).GetExitVertex());
}
}
}
public void Test_S2CellId_Continuity()
{
// Make sure that sequentially increasing cell ids form a continuous
// path over the surface of the sphere, i.e. there are no
// discontinuous jumps from one region to another.
double max_dist = S2.kMaxEdge.GetValue(kMaxWalkLevel);
S2CellId end = S2CellId.End(kMaxWalkLevel);
S2CellId id = S2CellId.Begin(kMaxWalkLevel);
for (; id != end; id = id.Next())
{
Assert.True(id.ToPointRaw().Angle(id.NextWrap().ToPointRaw()) <= max_dist);
Assert.Equal(id.NextWrap(), id.AdvanceWrap(1));
Assert.Equal(id, id.NextWrap().AdvanceWrap(-1));
// Check that the ToPointRaw() returns the center of each cell
// in (s,t) coordinates.
S2.XYZtoFaceUV(id.ToPointRaw(), out var u, out var v);
Assert2.Near(Math.IEEERemainder(S2.UVtoST(u), 0.5 * kCellSize), 0.0, S2.DoubleError);
Assert2.Near(Math.IEEERemainder(S2.UVtoST(v), 0.5 * kCellSize), 0.0, S2.DoubleError);
}
}