/// <summary>
/// Creates a new instance of PolylineSegmentCollection from an Ellipse.
/// </summary>
/// <param name="ellipse">An Ellipse instance.</param>
public PolylineSegmentCollection(Ellipse ellipse)
{
// PolylineSegmentCollection figuring the closed ellipse
double pi = Math.PI;
Plane plane = new Plane(Point3d.Origin, ellipse.Normal);
Point3d cen3d = ellipse.Center;
Point3d pt3d0 = cen3d + ellipse.MajorAxis;
Point3d pt3d4 = cen3d + ellipse.MinorAxis;
Point3d pt3d2 = ellipse.GetPointAtParameter(pi / 4.0);
Point2d cen = cen3d.Convert2d(plane);
Point2d pt0 = pt3d0.Convert2d(plane);
Point2d pt2 = pt3d2.Convert2d(plane);
Point2d pt4 = pt3d4.Convert2d(plane);
Line2d line01 = new Line2d(pt0, (pt4 - cen).GetNormal() + (pt2 - pt0).GetNormal());
Line2d line21 = new Line2d(pt2, (pt0 - pt4).GetNormal() + (pt0 - pt2).GetNormal());
Line2d line23 = new Line2d(pt2, (pt4 - pt0).GetNormal() + (pt4 - pt2).GetNormal());
Line2d line43 = new Line2d(pt4, (pt0 - cen).GetNormal() + (pt2 - pt4).GetNormal());
Line2d majAx = new Line2d(cen, pt0);
Line2d minAx = new Line2d(cen, pt4);
Point2d pt1 = line01.IntersectWith(line21)[0];
Point2d pt3 = line23.IntersectWith(line43)[0];
Point2d pt5 = pt3.TransformBy(Matrix2d.Mirroring(minAx));
Point2d pt6 = pt2.TransformBy(Matrix2d.Mirroring(minAx));
Point2d pt7 = pt1.TransformBy(Matrix2d.Mirroring(minAx));
Point2d pt8 = pt0.TransformBy(Matrix2d.Mirroring(minAx));
Point2d pt9 = pt7.TransformBy(Matrix2d.Mirroring(majAx));
Point2d pt10 = pt6.TransformBy(Matrix2d.Mirroring(majAx));
Point2d pt11 = pt5.TransformBy(Matrix2d.Mirroring(majAx));
Point2d pt12 = pt4.TransformBy(Matrix2d.Mirroring(majAx));
Point2d pt13 = pt3.TransformBy(Matrix2d.Mirroring(majAx));
Point2d pt14 = pt2.TransformBy(Matrix2d.Mirroring(majAx));
Point2d pt15 = pt1.TransformBy(Matrix2d.Mirroring(majAx));
double bulge1 = Math.Tan((pt4 - cen).GetAngleTo(pt1 - pt0) / 2.0);
double bulge2 = Math.Tan((pt1 - pt2).GetAngleTo(pt0 - pt4) / 2.0);
double bulge3 = Math.Tan((pt4 - pt0).GetAngleTo(pt3 - pt2) / 2.0);
double bulge4 = Math.Tan((pt3 - pt4).GetAngleTo(pt0 - cen) / 2.0);
_contents.Add(new PolylineSegment(pt0, pt1, bulge1));
_contents.Add(new PolylineSegment(pt1, pt2, bulge2));
_contents.Add(new PolylineSegment(pt2, pt3, bulge3));
_contents.Add(new PolylineSegment(pt3, pt4, bulge4));
_contents.Add(new PolylineSegment(pt4, pt5, bulge4));
_contents.Add(new PolylineSegment(pt5, pt6, bulge3));
_contents.Add(new PolylineSegment(pt6, pt7, bulge2));
_contents.Add(new PolylineSegment(pt7, pt8, bulge1));
_contents.Add(new PolylineSegment(pt8, pt9, bulge1));
_contents.Add(new PolylineSegment(pt9, pt10, bulge2));
_contents.Add(new PolylineSegment(pt10, pt11, bulge3));
_contents.Add(new PolylineSegment(pt11, pt12, bulge4));
_contents.Add(new PolylineSegment(pt12, pt13, bulge4));
_contents.Add(new PolylineSegment(pt13, pt14, bulge3));
_contents.Add(new PolylineSegment(pt14, pt15, bulge2));
_contents.Add(new PolylineSegment(pt15, pt0, bulge1));
// if the ellipse is an elliptical arc:
if (!ellipse.Closed)
{
double startParam, endParam;
Point2d startPoint = ellipse.StartPoint.Convert2d(plane);
Point2d endPoint = ellipse.EndPoint.Convert2d(plane);
// index of the PolylineSegment closest to the ellipse start point
int startIndex = GetClosestSegmentIndexTo(startPoint);
// start point on the PolylineSegment
Point2d pt = _contents[startIndex].ToCurve2d().GetClosestPointTo(startPoint).Point;
// if the point is equal to the PolylineSegment end point, jump the next segment in collection
if (pt.IsEqualTo(_contents[startIndex].EndPoint))
{
if (startIndex == 15)
{
startIndex = 0;
}
else
{
startIndex++;
}
startParam = 0.0;
}
// else get the 'parameter' at point on the PolylineSegment
else
{
startParam = _contents[startIndex].GetParameterOf(pt);
}
// index of the PolylineSegment closest to the ellipse end point
int endIndex = GetClosestSegmentIndexTo(endPoint);
// end point on the PolylineSegment
pt = _contents[endIndex].ToCurve2d().GetClosestPointTo(endPoint).Point;
// if the point is equals to the PolylineSegment startPoint, jump to the previous segment
if (pt.IsEqualTo(_contents[endIndex].StartPoint))
{
if (endIndex == 0)
{
endIndex = 15;
}
else
{
endIndex--;
}
endParam = 1.0;
}
// else get the 'parameter' at point on the PolylineSegment
else
{
endParam = _contents[endIndex].GetParameterOf(pt);
}
// if the parameter at start point is not equal to 0.0, calculate the bulge
if (startParam != 0.0)
{
_contents[startIndex].StartPoint = startPoint;
_contents[startIndex].Bulge = _contents[startIndex].Bulge * (1.0 - startParam);
}
// if the parameter at end point is not equal to 1.0, calculate the bulge
if (endParam != 1.0) //(endParam != 0.0)
{
_contents[endIndex].EndPoint = endPoint;
_contents[endIndex].Bulge = _contents[endIndex].Bulge * (endParam);
}
// if both points are on the same segment
if (startIndex == endIndex)
{
PolylineSegment segment = _contents[startIndex];
_contents.Clear();
_contents.Add(segment);
}
else if (startIndex < endIndex)
{
_contents.RemoveRange(endIndex + 1, 15 - endIndex);
_contents.RemoveRange(0, startIndex);
}
else
{
_contents.AddRange(_contents.GetRange(0, endIndex + 1));
_contents.RemoveRange(0, startIndex);
}
}
}