private bool loopsEqual(S2Loop a, S2Loop b, double maxError)
{
// Return true if two loops have the same cyclic vertex sequence.
if (a.NumVertices != b.NumVertices)
{
return(false);
}
for (var offset = 0; offset < a.NumVertices; ++offset)
{
if (S2.ApproxEquals(a.Vertex(offset), b.Vertex(0), maxError))
{
var success = true;
for (var i = 0; i < a.NumVertices; ++i)
{
if (!S2.ApproxEquals(a.Vertex(i + offset), b.Vertex(i), maxError))
{
success = false;
break;
}
}
if (success)
{
return(true);
}
// Otherwise continue looping. There may be more than one candidate
// starting offset since vertices are only matched approximately.
}
}
return(false);
}
public void Test_GetCentroid_Polyline()
{
// Checks that points are ignored when computing the centroid.
Assert.True(S2.ApproxEquals(
new S2Point(1, 1, 0),
S2ShapeIndexMeasures.GetCentroid(MakeIndexOrDie("5:5 | 6:6 # 0:0, 0:90 #"))));
}
public void Test_GetCentroid_Polygon()
{
// Checks that points and polylines are ignored when computing the centroid.
Assert.True(S2.ApproxEquals(
new S2Point(S2.M_PI_4, S2.M_PI_4, S2.M_PI_4),
S2ShapeIndexMeasures.GetCentroid(MakeIndexOrDie("5:5 # 6:6, 7:7 # 0:0, 0:90, 90:0"))));
}
// Given a point X and an edge AB, check that the distance from X to AB is
// "distance_radians" and the closest point on AB is "expected_closest".
private static void CheckDistance(S2Point x, S2Point a, S2Point b, double distance_radians, S2Point expected_closest)
{
x = x.Normalize();
a = a.Normalize();
b = b.Normalize();
expected_closest = expected_closest.Normalize();
Assert2.Near(distance_radians, S2.GetDistance(x, a, b).Radians, S2.DoubleError);
S2Point closest = S2.Project(x, a, b);
Assert.True(S2Pred.CompareEdgeDistance(
closest, a, b, new S1ChordAngle(S2.kProjectPerpendicularErrorS1Angle)) < 0);
// If X is perpendicular to AB then there is nothing further we can expect.
if (distance_radians != S2.M_PI_2)
{
if (expected_closest == new S2Point())
{
// This special value says that the result should be A or B.
Assert.True(closest == a || closest == b);
}
else
{
Assert.True(S2.ApproxEquals(closest, expected_closest));
}
}
S1ChordAngle min_distance = S1ChordAngle.Zero;
Assert.False(S2.UpdateMinDistance(x, a, b, ref min_distance));
min_distance = S1ChordAngle.Infinity;
Assert.True(S2.UpdateMinDistance(x, a, b, ref min_distance));
Assert2.Near(distance_radians, min_distance.ToAngle().Radians, S2.DoubleError);
}
public void testConversion()
{
// Test special cases: poles, "date line"
assertDoubleNear(
new S2LatLng(S2LatLng.FromDegrees(90.0, 65.0).ToPoint()).Lat.Degrees, 90.0);
assertEquals(
new S2LatLng(S2LatLng.FromRadians(-S2.PiOver2, 1).ToPoint()).Lat.Radians, -S2.PiOver2);
assertDoubleNear(
Math.Abs(new S2LatLng(S2LatLng.FromDegrees(12.2, 180.0).ToPoint()).Lng.Degrees), 180.0);
assertEquals(
Math.Abs(new S2LatLng(S2LatLng.FromRadians(0.1, -S2.Pi).ToPoint()).Lng.Radians),
S2.Pi);
// Test a bunch of random points.
for (var i = 0; i < 100000; ++i)
{
var p = randomPoint();
assertTrue(S2.ApproxEquals(p, new S2LatLng(p).ToPoint()));
}
// Test generation from E5
var test = S2LatLng.FromE5(123456, 98765);
assertDoubleNear(test.Lat.Degrees, 1.23456);
assertDoubleNear(test.Lng.Degrees, 0.98765);
}
public void Test_GetCentroid_Polygon()
{
// GetCentroid returns the centroid multiplied by the area of the polygon.
Assert.True(S2.ApproxEquals(
new S2Point(S2.M_PI_4, S2.M_PI_4, S2.M_PI_4),
S2.GetCentroid(MakeLaxPolygonOrDie("0:0, 0:90, 90:0"))));
}
public void Test_GetCentroid_Polyline()
{
// GetCentroid returns the centroid multiplied by the length of the polyline.
Assert.True(S2.ApproxEquals(
new S2Point(1, 1, 0),
S2ShapeIndexMeasures.GetCentroid(MakeIndexOrDie("0:0, 0:90"))));
}
void TestProjectUnproject(Projection projection, R2Point px, S2Point x)
{
// The arguments are chosen such that projection is exact, but
// unprojection may not be.
Assert.Equal(px, projection.Project(x));
Assert.True(S2.ApproxEquals(x, projection.Unproject(px)));
}
public void Test_EdgeTrueCentroid_SemiEquator()
{
// Test the centroid of polyline ABC that follows the equator and consists
// of two 90 degree edges (i.e., C = -A). The centroid (multiplied by
// length) should point toward B and have a norm of 2.0. (The centroid
// itself has a norm of 2/Pi, and the total edge length is Pi.)
S2Point a = new(0, -1, 0), b = new(1, 0, 0), c = new(0, 1, 0);
S2Point centroid = S2Centroid.TrueCentroid(a, b) + S2Centroid.TrueCentroid(b, c);
Assert.True(S2.ApproxEquals(b, centroid.Normalize()));
Assert2.DoubleEqual(2.0, centroid.Norm());
}
public void Test_S2LatLng_TestConversion()
{
// Test special cases: poles, "date line"
Assert2.DoubleEqual(90.0, new S2LatLng(S2LatLng.FromDegrees(90.0, 65.0).ToPoint()).Lat().GetDegrees());
Assert.Equal(-S2.M_PI_2, new S2LatLng(S2LatLng.FromRadians(-S2.M_PI_2, 1).ToPoint()).LatRadians);
Assert2.DoubleEqual(180.0, Math.Abs(new S2LatLng(S2LatLng.FromDegrees(12.2, 180.0).ToPoint()).Lng().GetDegrees()));
Assert.Equal(Math.PI, Math.Abs(new S2LatLng(S2LatLng.FromRadians(0.1, -Math.PI).ToPoint()).LngRadians));
// Test a bunch of random points.
for (int i = 0; i < 100000; ++i)
{
S2Point p = S2Testing.RandomPoint();
Assert.True(S2.ApproxEquals(p, new S2LatLng(p).ToPoint()));
}
}
public void Test_S2_Frames()
{
var z = new S2Point(0.2, 0.5, -3.3).Normalize();
var m = S2.GetFrame(z);
Assert.True(S2.ApproxEquals(m.Col(2), z));
Assert.True(m.Col(0).IsUnitLength());
Assert.True(m.Col(1).IsUnitLength());
Assert2.DoubleEqual(m.Det(), 1);
Assert.True(S2.ApproxEquals(S2.ToFrame(m, m.Col(0)), new(1, 0, 0)));
Assert.True(S2.ApproxEquals(S2.ToFrame(m, m.Col(1)), new(0, 1, 0)));
Assert.True(S2.ApproxEquals(S2.ToFrame(m, m.Col(2)), new(0, 0, 1)));
Assert.True(S2.ApproxEquals(S2.FromFrame(m, new(1, 0, 0)), m.Col(0)));
Assert.True(S2.ApproxEquals(S2.FromFrame(m, new(0, 1, 0)), m.Col(1)));
Assert.True(S2.ApproxEquals(S2.FromFrame(m, new(0, 0, 1)), m.Col(2)));
}
public void testInterpolate()
{
var vertices = new List <S2Point>();
vertices.Add(new S2Point(1, 0, 0));
vertices.Add(new S2Point(0, 1, 0));
vertices.Add(S2Point.Normalize(new S2Point(0, 1, 1)));
vertices.Add(new S2Point(0, 0, 1));
var line = new S2Polyline(vertices);
assertEquals(line.Interpolate(-0.1), vertices[0]);
assertTrue(S2.ApproxEquals(
line.Interpolate(0.1), S2Point.Normalize(new S2Point(1, Math.Tan(0.2 * S2.Pi / 2), 0))));
assertTrue(S2.ApproxEquals(line.Interpolate(0.25), S2Point.Normalize(new S2Point(1, 1, 0))));
assertTrue(S2.ApproxEquals(line.Interpolate(0.5), vertices[1]));
assertTrue(S2.ApproxEquals(line.Interpolate(0.75), vertices[2]));
assertTrue(S2.ApproxEquals(line.Interpolate(1.1), vertices[3]));
}
public void testProject()
{
var latLngs = new List <S2Point>();
latLngs.Add(S2LatLng.FromDegrees(0, 0).ToPoint());
latLngs.Add(S2LatLng.FromDegrees(0, 1).ToPoint());
latLngs.Add(S2LatLng.FromDegrees(0, 2).ToPoint());
latLngs.Add(S2LatLng.FromDegrees(1, 2).ToPoint());
var line = new S2Polyline(latLngs);
var edgeIndex = -1;
S2Point testPoint = default(S2Point);
testPoint = S2LatLng.FromDegrees(0.5, -0.5).ToPoint();
edgeIndex = line.GetNearestEdgeIndex(testPoint);
assertTrue(S2.ApproxEquals(
line.ProjectToEdge(testPoint, edgeIndex), S2LatLng.FromDegrees(0, 0).ToPoint()));
assertEquals(0, edgeIndex);
testPoint = S2LatLng.FromDegrees(0.5, 0.5).ToPoint();
edgeIndex = line.GetNearestEdgeIndex(testPoint);
assertTrue(S2.ApproxEquals(
line.ProjectToEdge(testPoint, edgeIndex), S2LatLng.FromDegrees(0, 0.5).ToPoint()));
assertEquals(0, edgeIndex);
testPoint = S2LatLng.FromDegrees(0.5, 1).ToPoint();
edgeIndex = line.GetNearestEdgeIndex(testPoint);
assertTrue(S2.ApproxEquals(
line.ProjectToEdge(testPoint, edgeIndex), S2LatLng.FromDegrees(0, 1).ToPoint()));
assertEquals(0, edgeIndex);
testPoint = S2LatLng.FromDegrees(-0.5, 2.5).ToPoint();
edgeIndex = line.GetNearestEdgeIndex(testPoint);
assertTrue(S2.ApproxEquals(
line.ProjectToEdge(testPoint, edgeIndex), S2LatLng.FromDegrees(0, 2).ToPoint()));
assertEquals(1, edgeIndex);
testPoint = S2LatLng.FromDegrees(2, 2).ToPoint();
edgeIndex = line.GetNearestEdgeIndex(testPoint);
assertTrue(S2.ApproxEquals(
line.ProjectToEdge(testPoint, edgeIndex), S2LatLng.FromDegrees(1, 2).ToPoint()));
assertEquals(2, edgeIndex);
}
// Converts the planar edge AB in the given projection to a chain of
// spherical geodesic edges and appends the vertices to "vertices".
//
// This method can be called multiple times with the same output vector to
// convert an entire polyline or loop. All vertices of the first edge are
// appended, but the first vertex of each subsequent edge is omitted (and is
// required to match that last vertex of the previous edge).
//
// Note that to construct an S2Loop, you must call vertices.pop_back() at
// the very end to eliminate the duplicate first and last vertex. Note also
// that if the given projection involves coordinate "wrapping" (e.g. across
// the 180 degree meridian) then the first and last vertices may not be
// exactly the same.
public void AppendUnprojected(R2Point a, R2Point b, List <S2Point> vertices)
{
var pointA = proj_.Unproject(a);
var pointB = proj_.Unproject(b);
if (!vertices.Any())
{
vertices.Add(pointA);
}
else
{
// Note that coordinate wrapping can create a small amount of error. For
// example in the edge chain "0:-175, 0:179, 0:-177", the first edge is
// transformed into "0:-175, 0:-181" while the second is transformed into
// "0:179, 0:183". The two coordinate pairs for the middle vertex
// ("0:-181" and "0:179") may not yield exactly the same S2Point.
System.Diagnostics.Debug.Assert(S2.ApproxEquals(vertices.Last(), pointA)); // Appended edges must form a chain
}
AppendUnprojected(a, pointA, b, pointB, vertices);
}
// Given two edges a0a1 and b0b1, check that the minimum distance between them
// is "distance_radians", and that GetEdgePairClosestPoints() returns
// "expected_a" and "expected_b" as the points that achieve this distance.
// S2Point.Empty may be passed for "expected_a" or "expected_b" to indicate
// that both endpoints of the corresponding edge are equally distant, and
// therefore either one might be returned.
//
// Parameters are passed by value so that this function can normalize them.
private static void CheckEdgePairMinDistance(S2Point a0, S2Point a1, S2Point b0, S2Point b1, double distance_radians, S2Point expected_a, S2Point expected_b)
{
a0 = a0.Normalize();
a1 = a1.Normalize();
b0 = b0.Normalize();
b1 = b1.Normalize();
expected_a = expected_a.Normalize();
expected_b = expected_b.Normalize();
var closest = S2.GetEdgePairClosestPoints(a0, a1, b0, b1);
S2Point actual_a = closest.Item1;
S2Point actual_b = closest.Item2;
if (expected_a == S2Point.Empty)
{
// This special value says that the result should be a0 or a1.
Assert.True(actual_a == a0 || actual_a == a1);
}
else
{
Assert.True(S2.ApproxEquals(expected_a, actual_a));
}
if (expected_b == S2Point.Empty)
{
// This special value says that the result should be b0 or b1.
Assert.True(actual_b == b0 || actual_b == b1);
}
else
{
Assert.True(S2.ApproxEquals(expected_b, actual_b));
}
S1ChordAngle min_distance = S1ChordAngle.Zero;
Assert.False(S2.UpdateEdgePairMinDistance(a0, a1, b0, b1, ref min_distance));
min_distance = S1ChordAngle.Infinity;
Assert.True(S2.UpdateEdgePairMinDistance(a0, a1, b0, b1, ref min_distance));
Assert2.Near(distance_radians, min_distance.Radians(), S2.DoubleError);
}
// Given a point X and an edge AB, check that the distance from X to AB is
// "distanceRadians" and the closest point on AB is "expectedClosest".
private static void checkDistance(
S2Point x, S2Point a, S2Point b, double distanceRadians, S2Point expectedClosest)
{
var kEpsilon = 1e-10;
x = S2Point.Normalize(x);
a = S2Point.Normalize(a);
b = S2Point.Normalize(b);
expectedClosest = S2Point.Normalize(expectedClosest);
assertEquals(distanceRadians, S2EdgeUtil.GetDistance(x, a, b).Radians, kEpsilon);
var closest = S2EdgeUtil.GetClosestPoint(x, a, b);
if (expectedClosest.Equals(new S2Point(0, 0, 0)))
{
// This special value says that the result should be A or B.
assertTrue(closest == a || closest == b);
}
else
{
assertTrue(S2.ApproxEquals(closest, expectedClosest));
}
}
// Common back end for AddPoint() and AddLatLng(). b and b_latlng
// must refer to the same vertex.
private void AddInternal(S2Point b, S2LatLng b_latlng)
{
// Simple consistency check to verify that b and b_latlng are alternate
// representations of the same vertex.
System.Diagnostics.Debug.Assert(S2.ApproxEquals(b, b_latlng.ToPoint()));
if (bound_.IsEmpty())
{
bound_ = bound_.AddPoint(b_latlng);
}
else
{
// First compute the cross product N = A x B robustly. This is the normal
// to the great circle through A and B. We don't use S2.RobustCrossProd()
// since that method returns an arbitrary vector orthogonal to A if the two
// vectors are proportional, and we want the zero vector in that case.
var n = (a_ - b).CrossProd(a_ + b); // N = 2 * (A x B)
// The relative error in N gets large as its norm gets very small (i.e.,
// when the two points are nearly identical or antipodal). We handle this
// by choosing a maximum allowable error, and if the error is greater than
// this we fall back to a different technique. Since it turns out that
// the other sources of error in converting the normal to a maximum
// latitude add up to at most 1.16 * S2Constants.DoubleEpsilon (see below), and it is
// desirable to have the total error be a multiple of S2Constants.DoubleEpsilon, we have
// chosen to limit the maximum error in the normal to 3.84 * S2Constants.DoubleEpsilon.
// It is possible to show that the error is less than this when
//
// n.Norm >= 8 * Math.Sqrt(3) / (3.84 - 0.5 - Math.Sqrt(3)) * S2Constants.DoubleEpsilon
// = 1.91346e-15 (about 8.618 * S2Constants.DoubleEpsilon)
var n_norm = n.Norm();
if (n_norm < 1.91346e-15)
{
// A and B are either nearly identical or nearly antipodal (to within
// 4.309 * S2Constants.DoubleEpsilon, or about 6 nanometers on the earth's surface).
if (a_.DotProd(b) < 0)
{
// The two points are nearly antipodal. The easiest solution is to
// assume that the edge between A and B could go in any direction
// around the sphere.
bound_ = S2LatLngRect.Full;
}
else
{
// The two points are nearly identical (to within 4.309 * S2Constants.DoubleEpsilon).
// In this case we can just use the bounding rectangle of the points,
// since after the expansion done by GetBound() this rectangle is
// guaranteed to include the (lat,lng) values of all points along AB.
bound_ = bound_.Union(S2LatLngRect.FromPointPair(a_latlng_, b_latlng));
}
}
else
{
// Compute the longitude range spanned by AB.
var lng_ab = S1Interval.FromPointPair(a_latlng_.LngRadians, b_latlng.LngRadians);
if (lng_ab.GetLength() >= Math.PI - 2 * S2.DoubleEpsilon)
{
// The points lie on nearly opposite lines of longitude to within the
// maximum error of the calculation. (Note that this test relies on
// the fact that Math.PI is slightly less than the true value of Pi, and
// that representable values near Math.PI are 2 * S2Constants.DoubleEpsilon apart.)
// The easiest solution is to assume that AB could go on either side
// of the pole.
lng_ab = S1Interval.Full;
}
// Next we compute the latitude range spanned by the edge AB. We start
// with the range spanning the two endpoints of the edge:
var lat_ab = R1Interval.FromPointPair(a_latlng_.LatRadians, b_latlng.LatRadians);
// This is the desired range unless the edge AB crosses the plane
// through N and the Z-axis (which is where the great circle through A
// and B attains its minimum and maximum latitudes). To test whether AB
// crosses this plane, we compute a vector M perpendicular to this
// plane and then project A and B onto it.
var m = n.CrossProd(new S2Point(0, 0, 1));
var m_a = m.DotProd(a_);
var m_b = m.DotProd(b);
// We want to test the signs of "m_a" and "m_b", so we need to bound
// the error in these calculations. It is possible to show that the
// total error is bounded by
//
// (1 + Math.Sqrt(3)) * S2Constants.DoubleEpsilon * n_norm + 8 * Math.Sqrt(3) * (S2Constants.DoubleEpsilon**2)
// = 6.06638e-16 * n_norm + 6.83174e-31
double m_error = 6.06638e-16 * n_norm + 6.83174e-31;
if (m_a * m_b < 0 || Math.Abs(m_a) <= m_error || Math.Abs(m_b) <= m_error)
{
// Minimum/maximum latitude *may* occur in the edge interior.
//
// The maximum latitude is 90 degrees minus the latitude of N. We
// compute this directly using atan2 in order to get maximum accuracy
// near the poles.
//
// Our goal is compute a bound that contains the computed latitudes of
// all S2Points P that pass the point-in-polygon containment test.
// There are three sources of error we need to consider:
// - the directional error in N (at most 3.84 * S2Constants.DoubleEpsilon)
// - converting N to a maximum latitude
// - computing the latitude of the test point P
// The latter two sources of error are at most 0.955 * S2Constants.DoubleEpsilon
// individually, but it is possible to show by a more complex analysis
// that together they can add up to at most 1.16 * S2Constants.DoubleEpsilon, for a
// total error of 5 * S2Constants.DoubleEpsilon.
//
// We add 3 * S2Constants.DoubleEpsilon to the bound here, and GetBound() will pad
// the bound by another 2 * S2Constants.DoubleEpsilon.
var max_lat = Math.Min(
Math.Atan2(Math.Sqrt(n[0] * n[0] + n[1] * n[1]), Math.Abs(n[2])) + 3 * S2.DoubleEpsilon,
S2.M_PI_2);
// In order to get tight bounds when the two points are close together,
// we also bound the min/max latitude relative to the latitudes of the
// endpoints A and B. First we compute the distance between A and B,
// and then we compute the maximum change in latitude between any two
// points along the great circle that are separated by this distance.
// This gives us a latitude change "budget". Some of this budget must
// be spent getting from A to B; the remainder bounds the round-trip
// distance (in latitude) from A or B to the min or max latitude
// attained along the edge AB.
//
// There is a maximum relative error of 4.5 * DBL_EPSILON in computing
// the squared distance (a_ - b), which means a maximum error of (4.5
// / 2 + 0.5) == 2.75 * DBL_EPSILON in computing Norm(). The sin()
// and multiply each have a relative error of 0.5 * DBL_EPSILON which
// we round up to a total of 4 * DBL_EPSILON.
var lat_budget_z = 0.5 * (a_ - b).Norm() * Math.Sin(max_lat);
const double folded = (1 + 4 * S2.DoubleEpsilon);
var lat_budget = 2 * Math.Asin(Math.Min(folded * lat_budget_z, 1.0));
var max_delta = 0.5 * (lat_budget - lat_ab.GetLength()) + S2.DoubleEpsilon;
// Test whether AB passes through the point of maximum latitude or
// minimum latitude. If the dot product(s) are small enough then the
// result may be ambiguous.
if (m_a <= m_error && m_b >= -m_error)
{
lat_ab = new R1Interval(lat_ab.Lo, Math.Min(max_lat, lat_ab.Hi + max_delta));
}
if (m_b <= m_error && m_a >= -m_error)
{
lat_ab = new R1Interval(Math.Max(-max_lat, lat_ab.Lo - max_delta), lat_ab.Lo);
}
}
bound_ = bound_.Union(new S2LatLngRect(lat_ab, lng_ab));
}
}
a_ = b;
a_latlng_ = b_latlng;
}
static void TestSubdivide(S2Cell cell)
{
GatherStats(cell);
if (cell.IsLeaf())
{
return;
}
var children = new S2Cell[4];
Assert.True(cell.Subdivide(children));
S2CellId child_id = cell.Id.ChildBegin();
double exact_area = 0;
double approx_area = 0;
double average_area = 0;
for (int i = 0; i < 4; ++i, child_id = child_id.Next())
{
exact_area += children[i].ExactArea();
approx_area += children[i].ApproxArea();
average_area += children[i].AverageArea();
// Check that the child geometry is consistent with its cell ID.
Assert.Equal(child_id, children[i].Id);
Assert.True(S2.ApproxEquals(children[i].Center(), child_id.ToPoint()));
S2Cell direct = new(child_id);
Assert.Equal(direct.Face, children[i].Face);
Assert.Equal(direct.Level, children[i].Level);
Assert.Equal(direct.Orientation, children[i].Orientation);
Assert.Equal(direct.CenterRaw(), children[i].CenterRaw());
for (int k = 0; k < 4; ++k)
{
Assert.Equal(direct.VertexRaw(k), children[i].VertexRaw(k));
Assert.Equal(direct.EdgeRaw(k), children[i].EdgeRaw(k));
}
// Test Contains() and MayIntersect().
Assert.True(cell.Contains(children[i]));
Assert.True(cell.MayIntersect(children[i]));
Assert.False(children[i].Contains(cell));
Assert.True(cell.Contains(children[i].CenterRaw()));
for (int j = 0; j < 4; ++j)
{
Assert.True(cell.Contains(children[i].VertexRaw(j)));
if (j != i)
{
Assert.False(children[i].Contains(children[j].CenterRaw()));
Assert.False(children[i].MayIntersect(children[j]));
}
}
// Test GetCapBound and GetRectBound.
S2Cap parent_cap = cell.GetCapBound();
S2LatLngRect parent_rect = cell.GetRectBound();
if (cell.Contains(new S2Point(0, 0, 1)) || cell.Contains(new S2Point(0, 0, -1)))
{
Assert.True(parent_rect.Lng.IsFull());
}
S2Cap child_cap = children[i].GetCapBound();
S2LatLngRect child_rect = children[i].GetRectBound();
Assert.True(child_cap.Contains(children[i].Center()));
Assert.True(child_rect.Contains(children[i].CenterRaw()));
Assert.True(parent_cap.Contains(children[i].Center()));
Assert.True(parent_rect.Contains(children[i].CenterRaw()));
for (int j = 0; j < 4; ++j)
{
Assert.True(child_cap.Contains(children[i].Vertex(j)));
Assert.True(child_rect.Contains(children[i].Vertex(j)));
Assert.True(child_rect.Contains(children[i].VertexRaw(j)));
Assert.True(parent_cap.Contains(children[i].Vertex(j)));
Assert.True(parent_rect.Contains(children[i].Vertex(j)));
Assert.True(parent_rect.Contains(children[i].VertexRaw(j)));
if (j != i)
{
// The bounding caps and rectangles should be tight enough so that
// they exclude at least two vertices of each adjacent cell.
int cap_count = 0;
int rect_count = 0;
for (int k = 0; k < 4; ++k)
{
if (child_cap.Contains(children[j].Vertex(k)))
{
++cap_count;
}
if (child_rect.Contains(children[j].VertexRaw(k)))
{
++rect_count;
}
}
Assert.True(cap_count <= 2);
if (child_rect.LatLo().Radians > -S2.M_PI_2 &&
child_rect.LatHi().Radians < S2.M_PI_2)
{
// Bounding rectangles may be too large at the poles because the
// pole itself has an arbitrary fixed longitude.
Assert.True(rect_count <= 2);
}
}
}
// Check all children for the first few levels, and then sample randomly.
// We also always subdivide the cells containing a few chosen points so
// that we have a better chance of sampling the minimum and maximum metric
// values. kMaxSizeUV is the absolute value of the u- and v-coordinate
// where the cell size at a given level is maximal.
double kMaxSizeUV = 0.3964182625366691;
R2Point[] special_uv =
{
new R2Point(S2.DoubleEpsilon, S2.DoubleEpsilon), // Face center
new R2Point(S2.DoubleEpsilon, 1), // Edge midpoint
new R2Point(1, 1), // Face corner
new R2Point(kMaxSizeUV, kMaxSizeUV), // Largest cell area
new R2Point(S2.DoubleEpsilon, kMaxSizeUV), // Longest edge/diagonal
};
bool force_subdivide = false;
foreach (R2Point uv in special_uv)
{
if (children[i].BoundUV.Contains(uv))
{
force_subdivide = true;
}
}
var debugFlag =
#if s2debug
true;
#else
false;
#endif
if (force_subdivide ||
cell.Level < (debugFlag ? 5 : 6) ||
S2Testing.Random.OneIn(debugFlag ? 5 : 4))
{
TestSubdivide(children[i]);
}
}
// Check sum of child areas equals parent area.
//
// For ExactArea(), the best relative error we can expect is about 1e-6
// because the precision of the unit vector coordinates is only about 1e-15
// and the edge length of a leaf cell is about 1e-9.
//
// For ApproxArea(), the areas are accurate to within a few percent.
//
// For AverageArea(), the areas themselves are not very accurate, but
// the average area of a parent is exactly 4 times the area of a child.
Assert.True(Math.Abs(Math.Log(exact_area / cell.ExactArea())) <= Math.Abs(Math.Log((1 + 1e-6))));
Assert.True(Math.Abs(Math.Log((approx_area / cell.ApproxArea()))) <= Math.Abs(Math.Log((1.03))));
Assert.True(Math.Abs(Math.Log((average_area / cell.AverageArea()))) <= Math.Abs(Math.Log((1 + 1e-15))));
}
