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);
}
}
}
}