public void Epsilon()
{
LineD[] lines = new LineD[] { new LineD(0, 2, 5, 2), new LineD(3, 2.1, 5, 4) };
var results = FindBoth(lines);
Assert.AreEqual(0, results.Length);
results = MultiLineIntersection.FindSimple(lines, 1.0);
Assert.AreEqual(1, results.Length);
var result = results[0];
Assert.IsTrue(PointD.Equals(new PointD(3, 2), result.Shared, 1.0));
Assert.AreEqual(2, result.Lines.Length);
Assert.AreEqual(0, result.Lines[0]);
Assert.AreEqual(LineLocation.Between, result.Locations[0]);
Assert.AreEqual(1, result.Lines[1]);
Assert.AreEqual(LineLocation.Start, result.Locations[1]);
lines = new LineD[] { new LineD(3, 1, 1, 1), new LineD(1, 1.1, 3, 3), new LineD(1, 0.9, 3, -2) };
results = FindBoth(lines);
Assert.AreEqual(0, results.Length);
results = MultiLineIntersection.FindSimple(lines, 1.0);
Assert.AreEqual(1, results.Length);
result = results[0];
Assert.IsTrue(PointD.Equals(new PointD(1, 1), result.Shared, 1.0));
Assert.AreEqual(3, result.Lines.Length);
Assert.AreEqual(0, result.Lines[0]);
Assert.AreEqual(LineLocation.End, result.Locations[0]);
Assert.AreEqual(1, result.Lines[1]);
Assert.AreEqual(LineLocation.Start, result.Locations[1]);
Assert.AreEqual(2, result.Lines[2]);
Assert.AreEqual(LineLocation.Start, result.Locations[1]);
}
private MultiLinePoint[] FindBoth(LineD[] lines)
{
var brute = MultiLineIntersection.FindSimple(lines);
var sweep = MultiLineIntersection.Find(lines);
CompareResults(brute, sweep);
return(brute);
}
private void DrawIntersections(LineD[] lines)
{
const double radius = 4.0;
// generate new random line set if desired
if (lines == null)
{
Size scale = new Size(OutputBox.Width - 4 * radius, OutputBox.Height - 4 * radius);
int count = MersenneTwister.Default.Next(3, 20);
lines = new LineD[count];
for (int i = 0; i < lines.Length; i++)
{
lines[i] = GeoAlgorithms.RandomLine(
2 * radius, 2 * radius, scale.Width, scale.Height);
}
}
_lines = lines;
double epsilon = (double)ToleranceUpDown.Value;
_crossings = (epsilon > 0.0 ?
MultiLineIntersection.FindSimple(lines, epsilon) :
MultiLineIntersection.FindSimple(lines));
LinesLabel.Content = String.Format("{0}/{1}", lines.Length, _crossings.Length);
OutputBox.Children.Clear();
// draw line set
foreach (LineD line in lines)
{
var shape = new Line()
{
X1 = line.Start.X, Y1 = line.Start.Y,
X2 = line.End.X, Y2 = line.End.Y,
Stroke = Brushes.Black
};
OutputBox.Children.Add(shape);
}
// draw intersections as hollow circles
foreach (var crossing in _crossings)
{
var circle = new Ellipse()
{
Width = 2 * radius, Height = 2 * radius,
Stroke = Brushes.Red
};
Canvas.SetLeft(circle, crossing.Shared.X - radius);
Canvas.SetTop(circle, crossing.Shared.Y - radius);
OutputBox.Children.Add(circle);
}
}
/// <summary>
/// Creates a random <see cref="Subdivision"/> with the specified number of full edges and
/// comparison epsilon.</summary>
/// <param name="size">
/// The number of full edges, i.e. half the number of <see cref="Subdivision.Edges"/>, in
/// the returned <see cref="Subdivision"/>.</param>
/// <param name="epsilon">
/// The maximum absolute difference at which two coordinates should be considered equal.
/// </param>
/// <returns>
/// A new random <see cref="Subdivision"/> with the specified <paramref name="size"/> and
/// <paramref name="epsilon"/>.</returns>
private static Subdivision CreateSubdivision(int size, double epsilon)
{
LineD[] lines = new LineD[size];
for (int i = 0; i < size; i++)
{
lines[i] = GeoAlgorithms.RandomLine(0, 0, 1000, 1000);
}
// split random set into non-intersecting line segments
var crossings = MultiLineIntersection.FindSimple(lines, epsilon);
var splitLines = MultiLineIntersection.Split(lines, crossings);
Array.Copy(splitLines, lines, size);
// re-randomize lines to eliminate split ordering
CollectionsUtility.Randomize(lines);
Subdivision division = Subdivision.FromLines(lines);
division.Validate();
return(division);
}