private Arc AlignmentArcToSpeckle(CivilDB.AlignmentSubEntityArc arc)
{
// calculate midpoint of chord as between start and end point
Point2d chordMid = new Point2d((arc.StartPoint.X + arc.EndPoint.X) / 2, (arc.StartPoint.Y + arc.EndPoint.Y) / 2);
// calculate sagitta as radius minus distance between arc center and chord midpoint
var sagitta = arc.Radius - arc.CenterPoint.GetDistanceTo(chordMid);
// get unit vector from arc center to chord mid
var midVector = arc.CenterPoint.GetVectorTo(chordMid);
var unitMidVector = midVector.DivideBy(midVector.Length);
// get midpoint of arc by moving chord mid point the length of the sagitta along mid vector
var midPoint = chordMid.Add(unitMidVector.MultiplyBy(sagitta));
// find arc plane (normal is in clockwise dir)
var center3 = new Point3d(arc.CenterPoint.X, arc.CenterPoint.Y, 0);
Acad.Plane plane = (arc.Clockwise) ? new Acad.Plane(center3, Vector3d.ZAxis.MultiplyBy(-1)) : new Acad.Plane(center3, Vector3d.ZAxis);
// calculate start and end angles
var startVector = new Vector3d(arc.StartPoint.X - center3.X, arc.StartPoint.Y - center3.Y, 0);
var endVector = new Vector3d(arc.EndPoint.X - center3.X, arc.EndPoint.Y - center3.Y, 0);
var startAngle = startVector.AngleOnPlane(plane);
var endAngle = endVector.AngleOnPlane(plane);
// calculate total angle.
// TODO: This needs to be improved with more research into autocad .AngleOnPlane() return values (negative angles, etc).
var totalAngle = (arc.Clockwise) ? System.Math.Abs(endAngle - startAngle) : System.Math.Abs(endAngle - startAngle);
// create arc
var _arc = new Arc(PlaneToSpeckle(plane), arc.Radius, startAngle, endAngle, totalAngle, ModelUnits);
_arc.startPoint = PointToSpeckle(arc.StartPoint);
_arc.endPoint = PointToSpeckle(arc.EndPoint);
_arc.midPoint = PointToSpeckle(midPoint);
_arc.domain = IntervalToSpeckle(new Acad.Interval(0, 1, tolerance));
_arc.length = arc.Length;
return(_arc);
}
internal AlignmentArc(C3dDb.AlignmentSubEntityArc subEntityArc) : base(subEntityArc)
{
_pIPoint = PointData.FromPointObject
(ReflectionSupport.GetProperty(subEntityArc, "PIPoint", null));
}