// Check that the curvature is *identical* when the vertex order is
// rotated, and that the sign is inverted when the vertices are reversed.
private static void CheckCurvatureInvariants(S2PointLoopSpan loop_in)
{
S2.LoopOrder order_in = S2.GetCanonicalLoopOrder(loop_in);
var loop = loop_in.ToList();
double expected = S2.GetCurvature(loop);
for (int i = 0; i < loop.Count; ++i)
{
loop.Reverse();
Assert.Equal((expected == S2.M_2_PI) ? expected : -expected,
S2.GetCurvature(loop));
ExpectSameOrder(loop_in, order_in, loop, S2.GetCanonicalLoopOrder(loop));
loop.Reverse();
loop.RotateInPlace(1);
Assert.Equal(expected, S2.GetCurvature(loop));
ExpectSameOrder(loop_in, order_in, loop, S2.GetCanonicalLoopOrder(loop));
}
}
// Given a loop whose vertices are represented as characters (such as "abcd" or
// "abccb"), verify that S2.GetCanonicalLoopOrder returns the given result.
private void TestCanonicalLoopOrder(string input_str, S2.LoopOrder expected_order)
{
Assert.Equal(expected_order, S2.GetCanonicalLoopOrder(MakeTestLoop(input_str)));
}