/// <summary>
/// Finds the points of intersection between a ray and an arc. The resulting lambdas along the ray are sorted in
/// ascending order, so the "first" intersection is always in lambda1 (if any). Lambda may be NaN if there is no
/// intersection (or no "second" intersection).</summary>
public static void RayWithArc(ref EdgeD ray, ref ArcD arc,
out double lambda1, out double lambda2)
{
RayWithCircle(ref ray, ref arc.Circle, out lambda1, out lambda2);
var sweepdir = Math.Sign(arc.AngleSweep);
if (!double.IsNaN(lambda1))
{
var dir = ((ray.Start + lambda1 * (ray.End - ray.Start)) - arc.Circle.Center).Theta();
if (!(GeomUt.AngleDifference(arc.AngleStart, dir) * sweepdir > 0 && GeomUt.AngleDifference(arc.AngleStart + arc.AngleSweep, dir) * sweepdir < 0))
{
lambda1 = double.NaN;
}
}
if (!double.IsNaN(lambda2))
{
var dir = ((ray.Start + lambda2 * (ray.End - ray.Start)) - arc.Circle.Center).Theta();
if (!(GeomUt.AngleDifference(arc.AngleStart, dir) * sweepdir > 0 && GeomUt.AngleDifference(arc.AngleStart + arc.AngleSweep, dir) * sweepdir < 0))
{
lambda2 = double.NaN;
}
}
if (double.IsNaN(lambda1) && !double.IsNaN(lambda2))
{
lambda1 = lambda2;
lambda2 = double.NaN;
}
}
private void assertNormalizedAngle(double input, double expected)
{
double pi = Math.PI;
double epsilon = 1e-10;
Assert.AreEqual(expected, GeomUt.NormalizedAngle(input), epsilon);
Assert.AreEqual(expected, GeomUt.NormalizedAngle(input + 2 * pi), epsilon);
Assert.AreEqual(expected, GeomUt.NormalizedAngle(input - 2 * pi), epsilon);
Assert.AreEqual(expected, GeomUt.NormalizedAngle(input + 4 * pi), epsilon);
Assert.AreEqual(expected, GeomUt.NormalizedAngle(input - 4 * pi), epsilon);
Assert.AreEqual(expected, GeomUt.NormalizedAngle(input + 6 * pi), epsilon);
Assert.AreEqual(expected, GeomUt.NormalizedAngle(input - 6 * pi), epsilon);
}
