public void Test_S2ClosestEdgeQuery_TrueDistanceLessThanS1ChordAngleDistance()
{
// Tests that IsConservativeDistanceLessOrEqual returns points where the
// true distance is slightly less than the one computed by S1ChordAngle.
//
// The points below had the worst error from among 100,000 random pairs.
S2Point p0 = new(0.78516762584829192, -0.50200400690845970, -0.36263449417782678);
S2Point p1 = new(0.78563011732429433, -0.50187655940493503, -0.36180828883938054);
// The S1ChordAngle distance is ~4 ulps greater than the true distance.
Distance dist1 = new(p0, p1);
var limit = dist1.Predecessor().Predecessor().Predecessor().Predecessor();
Assert.True(S2Pred.CompareDistance(p0, p1, limit) < 0);
// Verify that IsConservativeDistanceLessOrEqual() still returns "p1".
S2Point[] index_points = new[] { p0 };
MutableS2ShapeIndex index = new();
index.Add(new S2PointVectorShape(index_points));
S2ClosestEdgeQuery query = new(index);
S2ClosestEdgeQuery.PointTarget target1 = new(p1);
Assert.False(query.IsDistanceLess(target1, limit));
Assert.False(query.IsDistanceLessOrEqual(target1, limit));
Assert.True(query.IsConservativeDistanceLessOrEqual(target1, limit));
}
public void Test_S1ChordAngle_GetS2PointConstructorMaxError()
{
// Check that the error bound returned by GetS2PointConstructorMaxError() is
// large enough.
for (var iter = 0; iter < 100000; ++iter)
{
S2Testing.Random.Reset(iter); // Easier to reproduce a specific case.
var x = S2Testing.RandomPoint();
var y = S2Testing.RandomPoint();
if (S2Testing.Random.OneIn(10))
{
// Occasionally test a point pair that is nearly identical or antipodal.
var r = S1Angle.FromRadians(S2.DoubleError * S2Testing.Random.RandDouble());
y = S2.GetPointOnLine(x, y, r);
if (S2Testing.Random.OneIn(2))
{
y = -y;
}
}
S1ChordAngle dist = new(x, y);
var error = dist.GetS2PointConstructorMaxError();
var er1 = S2Pred.CompareDistance(x, y, dist.PlusError(error));
if (er1 > 0)
{
}
Assert.True(er1 <= 0);
var er2 = S2Pred.CompareDistance(x, y, dist.PlusError(-error));
if (er2 < 0)
{
}
Assert.True(er2 >= 0);
}
}
public void Test_S2ClosestEdgeQuery_IsConservativeDistanceLessOrEqual()
{
// Test
int num_tested = 0;
int num_conservative_needed = 0;
for (int iter = 0; iter < 1000; ++iter)
{
S2Testing.Random.Reset(iter + 1); // Easier to reproduce a specific case.
S2Point x = S2Testing.RandomPoint();
S2Point dir = S2Testing.RandomPoint();
S1Angle r = S1Angle.FromRadians(Math.PI * Math.Pow(1e-30, S2Testing.Random.RandDouble()));
S2Point y = S2.InterpolateAtDistance(r, x, dir);
Distance limit = new(r);
if (S2Pred.CompareDistance(x, y, limit) <= 0)
{
MutableS2ShapeIndex index = new();
index.Add(new S2PointVectorShape(new S2Point[] { x }));
S2ClosestEdgeQuery query = new(index);
S2ClosestEdgeQuery.PointTarget target = new(y);
Assert.True(query.IsConservativeDistanceLessOrEqual(target, limit));
++num_tested;
if (!query.IsDistanceLess(target, limit))
{
++num_conservative_needed;
}
}
}
// Verify that in most test cases, the distance between the target points
// was close to the desired value. Also verify that at least in some test
// cases, the conservative distance test was actually necessary.
Assert.True(num_tested >= 300);
Assert.True(num_tested <= 700);
Assert.True(num_conservative_needed >= 25);
}