private static void Render(IEnumerable<LineSegment2> allLineSegments, Intersection[] intersections)
{
var allPoints = allLineSegments.SelectMany(l => new[] { l.End1, l.End2 }).Concat(intersections.Select(i => i.Point)).ToList();
var width = (int)Math.Ceiling(allPoints.Max(p => p.X));
var height = (int)Math.Ceiling(allPoints.Max(p => p.Y));
var linePen = new Pen(Color.White, 5);
var selectedLinePen = new Pen(Color.Yellow, 8);
var quadrilateralPen = new Pen(Color.Red, 5);
var form = new Form { ClientSize = new Size(width, height) };
var bitmap = new Bitmap(width, height);
using (var g = Graphics.FromImage(bitmap))
{
g.Clear(Color.Black);
foreach (var line in _sampleLineSegments)
g.DrawLine(linePen, (float)line.End1.X, (float)line.End1.Y, (float)line.End2.X, (float)line.End2.Y);
foreach (var line in intersections.SelectMany(i => new[] { i.Line1, i.Line2 }).Distinct())
g.DrawLine(selectedLinePen, (float)line.End1.X, (float)line.End1.Y, (float)line.End2.X, (float)line.End2.Y);
g.DrawPolygon(quadrilateralPen, intersections.Select(i => new PointF((float)i.Point.X, (float)i.Point.Y)).ToArray());
}
form.Controls.Add(new PictureBox { Image = bitmap, Width = width, Height = height });
form.ShowDialog();
}
private static double CalculateError(Intersection[] intersections)
{
var distanceError = intersections.Sum(
intersection =>
{
Func<double, double> calcDistancePenalty = d =>
{
if (d > 0 && d < 1)
{
// Itersection within the line segment is a bad sign, so penalise for it, proportionally
return -Math.Log(d > 0.5 ? 1 - d : d);
}
return 0;
};
return calcDistancePenalty(intersection.Distance1) + calcDistancePenalty(intersection.Distance2);
}
);
var angles = new[]
{
GetAcuteAngleBetweenPoints(intersections[0].Point, intersections[1].Point, intersections[2].Point),
GetAcuteAngleBetweenPoints(intersections[1].Point, intersections[2].Point, intersections[3].Point),
GetAcuteAngleBetweenPoints(intersections[2].Point, intersections[3].Point, intersections[0].Point),
GetAcuteAngleBetweenPoints(intersections[3].Point, intersections[0].Point, intersections[1].Point)
};
// Sum of squared errors
const double piOnTwo = Math.PI/2;
var angleError = angles.Sum(angle => Math.Pow(piOnTwo - Math.Abs(angle), 2));
return angleError + distanceError;
}