// 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);
}
private static S1Angle BruteForceDistance(S2LatLngRect a, S2LatLngRect b)
{
if (a.Intersects(b))
{
return(S1Angle.FromRadians(0));
}
// Compare every point in 'a' against every latitude edge and longitude edge
// in 'b', and vice-versa, for a total of 16 point-vs-latitude-edge tests and
// 16 point-vs-longitude-edge tests.
var pnt_a = new S2LatLng[4];
var pnt_b = new S2LatLng[4];
pnt_a[0] = new S2LatLng(a.LatLo(), a.LngLo());
pnt_a[1] = new S2LatLng(a.LatLo(), a.LngHi());
pnt_a[2] = new S2LatLng(a.LatHi(), a.LngHi());
pnt_a[3] = new S2LatLng(a.LatHi(), a.LngLo());
pnt_b[0] = new S2LatLng(b.LatLo(), b.LngLo());
pnt_b[1] = new S2LatLng(b.LatLo(), b.LngHi());
pnt_b[2] = new S2LatLng(b.LatHi(), b.LngHi());
pnt_b[3] = new S2LatLng(b.LatHi(), b.LngLo());
// Make arrays containing the lo/hi latitudes and the lo/hi longitude edges.
var lat_a = new S1Angle[2] {
a.LatLo(), a.LatHi()
};
var lat_b = new S1Angle[2] {
b.LatLo(), b.LatHi()
};
var lng_edge_a = new S2Point[][] { new S2Point[] { pnt_a[0].ToPoint(), pnt_a[3].ToPoint() },
new S2Point[] { pnt_a[1].ToPoint(), pnt_a[2].ToPoint() } };
var lng_edge_b = new S2Point[][] { new S2Point[] { pnt_b[0].ToPoint(), pnt_b[3].ToPoint() },
new S2Point[] { pnt_b[1].ToPoint(), pnt_b[2].ToPoint() } };
S1Angle min_distance = S1Angle.FromDegrees(180.0);
for (int i = 0; i < 4; ++i)
{
// For each point in a and b.
var current_a = pnt_a[i];
var current_b = pnt_b[i];
for (int j = 0; j < 2; ++j)
{
// Get distances to latitude and longitude edges.
S1Angle a_to_lat = GetDistance(current_a, lat_b[j], b.Lng);
S1Angle b_to_lat = GetDistance(current_b, lat_a[j], a.Lng);
S1Angle a_to_lng = S2.GetDistance(current_a.ToPoint(), lng_edge_b[j][0], lng_edge_b[j][1]);
S1Angle b_to_lng = S2.GetDistance(current_b.ToPoint(), lng_edge_a[j][0], lng_edge_a[j][1]);
min_distance = new[] { min_distance, a_to_lat, b_to_lat, a_to_lng, b_to_lng }.Min();
}
}
return(min_distance);
}
private static S1Angle BruteForceRectPointDistance(S2LatLngRect a, S2LatLng b)
{
if (a.Contains(b))
{
return(S1Angle.FromRadians(0));
}
S1Angle b_to_lo_lat = GetDistance(b, a.LatLo(), a.Lng);
S1Angle b_to_hi_lat = GetDistance(b, a.LatHi(), a.Lng);
S1Angle b_to_lo_lng = S2.GetDistance(b.ToPoint(), new S2LatLng(a.LatLo(), a.LngLo()).ToPoint(), new S2LatLng(a.LatHi(), a.LngLo()).ToPoint());
S1Angle b_to_hi_lng = S2.GetDistance(b.ToPoint(), new S2LatLng(a.LatLo(), a.LngHi()).ToPoint(), new S2LatLng(a.LatHi(), a.LngHi()).ToPoint());
return(new[] { b_to_lo_lat, b_to_hi_lat, b_to_lo_lng, b_to_hi_lng }.Min());
}