public static Point GetInsidePoint(IReadOnlyList<Point> points, Box boundingBox)
{
var y = (boundingBox.MinY + boundingBox.MaxY) / 2;
var xIntersections = new List<double>();
var point1 = points.Last();
foreach (var point2 in points)
{
if ((y > point1.Y) != (y > point2.Y))
{
xIntersections.Add((y - point2.Y) * (point1.X - point2.X) / (point1.Y - point2.Y) + point2.X);
}
point1 = point2;
}
xIntersections.Sort();
Debugger.BreakWhen(xIntersections.Count == 0 || xIntersections.Count % 2 != 0);
var x = (boundingBox.MinX + boundingBox.MaxX) / 2;
var maxDelta = double.NegativeInfinity;
for (var i = 0; i < xIntersections.Count - 1; i += 2)
{
var delta = Math.Abs(xIntersections[i] - xIntersections[i + 1]);
if (delta > maxDelta)
{
x = (xIntersections[i] + xIntersections[i + 1]) / 2;
maxDelta = delta;
}
}
var point = new Point(x, y);
#if DEBUG
Debugger.BreakWhen(!PointInPolygonTest.Contains(points, point));
#endif
return point;
}
public bool IntersectsWith(Box box)
{
return
box.MinX <= MaxX &&
box.MaxX >= MinX &&
box.MinY <= MaxY &&
box.MaxY >= MinY;
}
public Polyline([NotNull] IEnumerable<Point> points)
{
Points = points.ToReadOnlyList();
BoundingBox = new Box(
Points.Select(x => x.X).Min(),
Points.Select(x => x.X).Max(),
Points.Select(x => x.Y).Min(),
Points.Select(x => x.Y).Max());
}
private static void CalculateIntersections(SegmentBase segment1, SegmentBase segment2, bool skipInner, bool skipOuter)
{
var boundingBox1 = segment1.PolylineApproximation.BoundingBox;
var boundingBox2 = segment2.PolylineApproximation.BoundingBox;
if (!boundingBox1.IntersectsWith(boundingBox2))
{
return;
}
var points1 = segment1.PolylineApproximation.Points;
var points2 = segment2.PolylineApproximation.Points;
for (var i = 1; i < points1.Count; i++)
{
var p11 = points1[i - 1];
var p12 = points1[i];
var box1 = new Box(p11, p12);
if (!box1.IntersectsWith(boundingBox2))
{
continue;
}
for (var j = 1; j < points2.Count; j++)
{
var p21 = points2[j - 1];
var p22 = points2[j];
var box2 = new Box(p21, p22);
if (!box1.IntersectsWith(box2))
{
continue;
}
if ((skipInner && i == points1.Count - 1 && j == 1) ||
(skipOuter && i == 1 && j == points2.Count - 1))
{
continue;
}
var intersection = CalculateIntersection(p11, p12, p21, p22);
if (intersection.HasValue)
{
segment1.Intersections.Add(intersection.Value);
segment2.Intersections.Add(intersection.Value);
}
}
}
}
private static void CalculateSelfIntersections(SegmentBase segment)
{
if (!(segment is CubicBezierSegment))
{
// only cubic bezier segment can self-intersect
return;
}
var points = segment.PolylineApproximation.Points;
for (var i = 1; i < points.Count - 2; i++)
{
var p11 = points[i - 1];
var p12 = points[i];
var box1 = new Box(p11, p12);
for (var j = i + 2; j < points.Count; j++)
{
var p21 = points[j - 1];
var p22 = points[j];
var box2 = new Box(p21, p22);
if (!box1.IntersectsWith(box2))
{
continue;
}
var intersection = CalculateIntersection(p11, p12, p21, p22);
if (intersection.HasValue)
{
segment.Intersections.Add(intersection.Value);
}
}
}
}
