/// <summary>
/// Returns the centroid.
/// </summary>
public C2DPoint GetCentroid()
{
// Find the centroid and area of the straight line polygon.
C2DPoint Centroid = new C2DPoint(0, 0);
// C2DPoint pti = new C2DPoint();
// C2DPoint ptii;
double dArea = 0;
for (int i = 0; i < Lines.Count; i++)
{
C2DPoint pti = Lines[i].GetPointFrom();
C2DPoint ptii = Lines[i].GetPointTo();
Centroid.x += (pti.x + ptii.x) * (pti.x * ptii.y - ptii.x * pti.y);
Centroid.y += (pti.y + ptii.y) * (pti.x * ptii.y - ptii.x * pti.y);
dArea += pti.x * ptii.y - ptii.x * pti.y;
}
dArea = dArea / 2.0;
Centroid.x = Centroid.x / (6.0 * dArea);
Centroid.y = Centroid.y / (6.0 * dArea);
List <double> dSegAreas = new List <double>();
double dTotalArea = dArea;
List <C2DPoint> SegCentroids = new List <C2DPoint>();
for (int i = 0; i < Lines.Count; i++)
{
if (Lines[i] is C2DArc)
{
C2DSegment Seg = new C2DSegment(Lines[i] as C2DArc);
double dSegArea = Seg.GetAreaSigned();
dTotalArea += dSegArea;
dSegAreas.Add(dSegArea);
SegCentroids.Add(Seg.GetCentroid());
}
}
Centroid.Multiply(dArea);
for (int i = 0; i < dSegAreas.Count; i++)
{
Centroid.x += SegCentroids[i].x * dSegAreas[i];
Centroid.y += SegCentroids[i].y * dSegAreas[i];
}
Centroid.Multiply(1 / dTotalArea);
return(Centroid);
}
/// <summary>
/// Returns the centroid.
/// </summary>
public C2DPoint GetCentroid()
{
// Find the area first. Do it explicitly as we may need bits of the calc later.
var dSegAng = Arc.GetSegmentAngle();
var bBig = Arc.ArcOnRight == Arc.CentreOnRight;
var dRadius = Arc.Radius;
var dRadiusSquare = dRadius * dRadius;
var dCircleArea = dRadiusSquare * Constants.conPI;
var dArea = dRadiusSquare * ((dSegAng - Math.Sin(dSegAng)) / 2);
// Find the maximum length of the small segment along the direction of the line.
var dLength = Arc.Line.GetLength();
// Now find the average height of the segment over that line
var dHeight = dArea / dLength;
// Find the centre point on the line and the centre of the circle
var ptLineCen = new C2DPoint(Arc.Line.GetMidPoint());
var ptCircleCen = new C2DPoint(Arc.GetCircleCentre());
// Set up a line from the mid point on the line to the circle centre
// then set the length of it to the average height divided by 2. The end
// point of the line is then the centroid. If we are using the small bit,
// The line needs to be reversed.
var Line = new C2DLine(ptLineCen, ptCircleCen);
Line.vector.Reverse();
Line.vector.SetLength(dHeight / 2);
if (bBig)
{
var ptSmallCen = new C2DPoint(Line.GetPointTo());
// Return the weighted average of the 2 centroids.
ptCircleCen.Multiply(dCircleArea);
ptSmallCen.Multiply(dArea);
var pRes = ptCircleCen - ptSmallCen;
pRes.Multiply(1.0 / (dCircleArea - dArea));
return(pRes);
// return ( new C2DPoint(ptCircleCen * dCircleArea - ptSmallCen * dArea) ) / ( dCircleArea - dArea);
}
else
{
return(Line.GetPointTo());
}
}
/// <summary>
/// Calculates the centroid of the polygon by moving it according to each holes
/// weighted centroid.
/// </summary>
public C2DPoint GetCentroid()
{
C2DPoint HoleCen = new C2DPoint(0, 0);
if (_Holes.Count == 0)
{
return(Rim.GetCentroid());
}
C2DPoint PolyCen = Rim.GetCentroid();
double dPolyArea = Rim.GetArea();
double dHoleArea = 0;
for (int i = 0; i < _Holes.Count; i++)
{
dHoleArea += GetHole(i).GetArea();
}
if (dHoleArea == 0 || dHoleArea == dPolyArea)
{
return(Rim.GetCentroid());
}
else
{
for (int i = 0; i < _Holes.Count; i++)
{
C2DPoint pt = GetHole(i).GetCentroid();
pt.Multiply(GetHole(i).GetArea() / dHoleArea);
HoleCen += pt;
}
}
C2DVector Vec = new C2DVector(HoleCen, PolyCen);
Vec.Multiply(dHoleArea / (dPolyArea - dHoleArea));
PolyCen.Move(Vec);
return(PolyCen);
}
/// <summary>
/// Returns the centroid.
/// </summary>
public C2DPoint GetCentroid()
{
// Find the centroid and area of the straight line polygon.
C2DPoint Centroid = new C2DPoint(0, 0);
// C2DPoint pti = new C2DPoint();
// C2DPoint ptii;
double dArea = 0;
for (int i = 0; i < Lines.Count; i++)
{
C2DPoint pti = Lines[i].GetPointFrom();
C2DPoint ptii = Lines[i].GetPointTo();
Centroid.x += (pti.x + ptii.x) * (pti.x * ptii.y - ptii.x * pti.y);
Centroid.y += (pti.y + ptii.y) * (pti.x * ptii.y - ptii.x * pti.y);
dArea += pti.x * ptii.y - ptii.x * pti.y;
}
dArea = dArea / 2.0;
Centroid.x = Centroid.x / (6.0 * dArea);
Centroid.y = Centroid.y / (6.0 * dArea);
List<double> dSegAreas = new List<double>();
double dTotalArea = dArea;
List<C2DPoint> SegCentroids = new List<C2DPoint>();
for (int i = 0; i < Lines.Count; i++)
{
if (Lines[i] is C2DArc)
{
C2DSegment Seg = new C2DSegment( Lines[i] as C2DArc );
double dSegArea = Seg.GetAreaSigned();
dTotalArea += dSegArea;
dSegAreas.Add( dSegArea );
SegCentroids.Add( Seg.GetCentroid() );
}
}
Centroid.Multiply( dArea);
for (int i = 0; i < dSegAreas.Count; i++)
{
Centroid.x += SegCentroids[i].x * dSegAreas[i];
Centroid.y += SegCentroids[i].y * dSegAreas[i];
}
Centroid.Multiply( 1/ dTotalArea);
return Centroid;
}
/// <summary>
/// Returns the centroid.
/// </summary>
public C2DPoint GetCentroid()
{
// Find the area first. Do it explicitly as we may need bits of the calc later.
double dSegAng = Arc.GetSegmentAngle();
bool bBig = Arc.ArcOnRight == Arc.CentreOnRight;
double dRadius = Arc.Radius;
double dRadiusSquare = dRadius * dRadius;
double dCircleArea = dRadiusSquare * Constants.conPI;
double dArea = dRadiusSquare * ( (dSegAng - Math.Sin(dSegAng)) / 2);
// Find the maximum length of the small segment along the direction of the line.
double dLength = Arc.Line.GetLength();
// Now find the average height of the segment over that line
double dHeight = dArea / dLength;
// Find the centre point on the line and the centre of the circle
C2DPoint ptLineCen = new C2DPoint(Arc.Line.GetMidPoint());
C2DPoint ptCircleCen = new C2DPoint(Arc.GetCircleCentre());
// Set up a line from the mid point on the line to the circle centre
// then set the length of it to the average height divided by 2. The end
// point of the line is then the centroid. If we are using the small bit,
// The line needs to be reversed.
C2DLine Line = new C2DLine( ptLineCen, ptCircleCen);
Line.vector.Reverse();
Line.vector.SetLength( dHeight / 2 );
if (bBig)
{
C2DPoint ptSmallCen = new C2DPoint(Line.GetPointTo());
// Return the weighted average of the 2 centroids.
ptCircleCen.Multiply(dCircleArea);
ptSmallCen.Multiply(dArea);
C2DPoint pRes = ptCircleCen - ptSmallCen;
pRes.Multiply(1.0 / (dCircleArea - dArea));
return pRes;
// return ( new C2DPoint(ptCircleCen * dCircleArea - ptSmallCen * dArea) ) / ( dCircleArea - dArea);
}
else
return Line.GetPointTo();
}
