/// <summary>
/// Gets the centroid of the polyline 2d.
/// </summary>
/// <param name="pl">The instance to which the method applies.</param>
/// <returns>The centroid of the polyline 2d (WCS coordinates).</returns>
public static Point3d Centroid([NotNull] this Polyline2d pl)
{
var vertices = pl.GetVertices().ToArray();
var last = vertices.Length - 1;
var vertex = vertices[0];
var p0 = vertex.Position.Convert2d();
var cen = new Point2d(0.0, 0.0);
var area = 0.0;
var bulge = vertex.Bulge;
double tmpArea;
Point2d tmpPt;
var tri = new Triangle2d();
CircularArc2d arc;
if (Math.Abs(bulge) > 0.0001)
{
arc = pl.GetArcSegment2dAt(0);
tmpArea = arc.AlgebricArea();
tmpPt = arc.Centroid();
area += tmpArea;
cen += (new Point2d(tmpPt.X, tmpPt.Y) * tmpArea).GetAsVector();
}
for (var i = 1; i < last; i++)
{
var p1 = vertices[i].Position.Convert2d();
var p2 = vertices[i + 1].Position.Convert2d();
tri.Set(p0, p1, p2);
tmpArea = tri.AlgebricArea;
area += tmpArea;
cen += (tri.Centroid * tmpArea).GetAsVector();
bulge = vertices[i].Bulge;
if (Math.Abs(bulge) > 0.0001)
{
arc = pl.GetArcSegment2dAt(i);
tmpArea = arc.AlgebricArea();
tmpPt = arc.Centroid();
area += tmpArea;
cen += (new Point2d(tmpPt.X, tmpPt.Y) * tmpArea).GetAsVector();
}
}
bulge = vertices[last].Bulge;
if (Math.Abs(bulge) > 0.0001 && pl.Closed)
{
arc = pl.GetArcSegment2dAt(last);
tmpArea = arc.AlgebricArea();
tmpPt = arc.Centroid();
area += tmpArea;
cen += (new Point2d(tmpPt.X, tmpPt.Y) * tmpArea).GetAsVector();
}
cen = cen.DivideBy(area);
return(new Point3d(cen.X, cen.Y, pl.Elevation).TransformBy(Matrix3d.PlaneToWorld(pl.Normal)));
}
/// <summary>
/// Gets the centroid of the polyline 2d.
/// </summary>
/// <param name="pl">The instance to which the method applies.</param>
/// <returns>The centroid of the polyline 2d (WCS coordinates).</returns>
public static Point3d Centroid(this Polyline2d pl)
{
Vertex2d[] vertices = pl.GetVertices().ToArray();
int last = vertices.Length - 1;
Vertex2d vertex = vertices[0];
Point2d p0 = vertex.Position.Convert2d();
double elev = pl.Elevation;
Point2d cen = new Point2d(0.0, 0.0);
double area = 0.0;
double bulge = vertex.Bulge;
double tmpArea;
Point2d tmpPt;
Triangle2d tri = new Triangle2d();
CircularArc2d arc = new CircularArc2d();
if (bulge != 0.0)
{
arc = pl.GetArcSegment2dAt(0);
tmpArea = arc.SignedArea();
tmpPt = arc.Centroid();
area += tmpArea;
cen += ((new Point2d(tmpPt.X, tmpPt.Y)) * tmpArea).GetAsVector();
}
for (int i = 1; i < last; i++)
{
Point2d p1 = vertices[i].Position.Convert2d();
Point2d p2 = vertices[i + 1].Position.Convert2d();
tri.Set(p0, p1, p2);
tmpArea = tri.SignedArea;
area += tmpArea;
cen += (tri.Centroid * tmpArea).GetAsVector();
bulge = vertices[i].Bulge;
if (bulge != 0.0)
{
arc = pl.GetArcSegment2dAt(i);
tmpArea = arc.SignedArea();
tmpPt = arc.Centroid();
area += tmpArea;
cen += ((new Point2d(tmpPt.X, tmpPt.Y)) * tmpArea).GetAsVector();
}
}
bulge = vertices[last].Bulge;
if ((bulge != 0.0) && (pl.Closed == true))
{
arc = pl.GetArcSegment2dAt(last);
tmpArea = arc.SignedArea();
tmpPt = arc.Centroid();
area += tmpArea;
cen += ((new Point2d(tmpPt.X, tmpPt.Y)) * tmpArea).GetAsVector();
}
cen = cen.DivideBy(area);
return(new Point3d(cen.X, cen.Y, pl.Elevation).TransformBy(Matrix3d.PlaneToWorld(pl.Normal)));
}
