public void Test_LoopTestBase_GetAreaConsistentWithOrientation()
{
// Test that GetArea() returns an area near 0 for degenerate loops that
// contain almost no points, and an area near 4*Pi for degenerate loops that
// contain almost all points.
const int kMaxVertices = 6;
for (int i = 0; i < 50; ++i)
{
int num_vertices = 3 + S2Testing.Random.Uniform(kMaxVertices - 3 + 1);
// Repeatedly choose N vertices that are exactly on the equator until we
// find some that form a valid loop.
S2PointLoopSpan loop = new();
do
{
for (int i2 = 0; i2 < num_vertices; ++i2)
{
// We limit longitude to the range [0, 90] to ensure that the loop is
// degenerate (as opposed to following the entire equator).
loop.Add(
S2LatLng.FromRadians(0, S2Testing.Random.RandDouble() * S2.M_PI_2).ToPoint());
}
} while (!new S2Loop(loop, S2Debug.DISABLE).IsValid());
bool ccw = S2.IsNormalized(loop);
// The error bound is sufficient for current tests but not guaranteed.
_ = i + ": " + loop.ToDebugString();
Assert2.Near(ccw ? 0 : S2.M_4_PI, S2.GetArea(loop), 1e-14);
Assert.Equal(!ccw, new S2Loop(loop).Contains(new S2Point(0, 0, 1)));
}
}
