// 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 Test_S2_ProjectError()
{
for (int iter = 0; iter < 1000; ++iter)
{
S2Testing.Random.Reset(iter + 1); // Easier to reproduce a specific case.
S2Point a = ChoosePoint();
S2Point b = ChoosePoint();
S2Point n = S2.RobustCrossProd(a, b).Normalize();
S2Point x = S2Testing.SamplePoint(new S2Cap(n, S1Angle.FromRadians(1e-15)));
S2Point p = S2.Project(x, a, b);
Assert.True(S2Pred.CompareEdgeDistance(
p, a, b, new S1ChordAngle(S2.kProjectPerpendicularErrorS1Angle)) < 0);
}
}