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);
}
}
