/// <summary>
/// Convert into an array of polygons
/// </summary>
/// <remarks>
/// The polytree will nest deeply if solids are inside of holes. But Polygon2D would treat the solids inside of holes as their own
/// independent isntances
///
/// http://www.angusj.com/delphi/clipper/documentation/Docs/Units/ClipperLib/Classes/PolyTree/_Body.htm
/// </remarks>
private static Polygon2D[] ConvertOutput(PolyTree solution, double scaleInverse)
{
List<Polygon2D> retVal = new List<Polygon2D>();
// Walk the tree, and get all parents (need to look at contour count so that the root gets skipped)
foreach (PolyNode parent in ((PolyNode)solution).Descendants(o => o.Childs).Where(o => !o.IsHole && o.Contour.Count > 0))
{
// Convert the parent polygon
Point[] points = parent.Contour.Select(o => new Point(o.X * scaleInverse, o.Y * scaleInverse)).ToArray();
if (parent.Childs.Count == 0)
{
// No holes
retVal.Add(new Polygon2D(points));
}
else
{
List<Point[]> holes = new List<Point[]>();
foreach (PolyNode child in parent.Childs)
{
if (!child.IsHole)
{
throw new ApplicationException("Expected the child of a non hole to be a hole");
}
// Convert the hole polygon
holes.Add(child.Contour.Select(o => new Point(o.X * scaleInverse, o.Y * scaleInverse)).ToArray());
}
// Store with holes
retVal.Add(new Polygon2D(points, holes.ToArray()));
}
}
// Exit Function
return retVal.ToArray();
}
public static Polygon2D[] GetPolyUnion(Point[][] polygons)
{
if (polygons == null || polygons.Length == 0)
{
return new Polygon2D[0];
}
double scale = GetScale(polygons);
var convertedPolys = ConvertInput(polygons, scale);
Clipper clipper = new Clipper();
clipper.AddPolygons(convertedPolys, PolyType.ptSubject); // when doing union, I don't think it matters what is subject and what is union
//clipper.ForceSimple = true;
// Here is a page describing PolyFillType (nonzero is what you intuitively think of for a union)
// http://www.angusj.com/delphi/clipper/documentation/Docs/Units/ClipperLib/Types/PolyFillType.htm
PolyTree solution = new PolyTree();
if (!clipper.Execute(ClipType.ctUnion, solution, PolyFillType.pftNonZero, PolyFillType.pftNonZero))
{
return new Polygon2D[0];
}
return ConvertOutput(solution, 1d / scale);
}
//------------------------------------------------------------------------------
public static void PolyTreeToPolygons(PolyTree polytree, PolygonsClp polygons)
{
polygons.Clear();
polygons.Capacity = polytree.Total;
AddPolyNodeToPolygons(polytree, polygons);
}
//------------------------------------------------------------------------------
private void BuildResult2(PolyTree polytree)
{
polytree.Clear();
//add each output polygon/contour to polytree ...
polytree.m_AllPolys.Capacity = m_PolyOuts.Count;
for (int i = 0; i < m_PolyOuts.Count; i++)
{
OutRec outRec = m_PolyOuts[i];
int cnt = PointCount(outRec.pts);
if (cnt < 3) continue;
FixHoleLinkage(outRec);
PolyNode pn = new PolyNode();
polytree.m_AllPolys.Add(pn);
outRec.polyNode = pn;
pn.m_polygon.Capacity = cnt;
OutPt op = outRec.pts;
for (int j = 0; j < cnt; j++)
{
pn.m_polygon.Add(op.pt);
op = op.prev;
}
}
//fixup PolyNode links etc ...
polytree.m_Childs.Capacity = m_PolyOuts.Count;
for (int i = 0; i < m_PolyOuts.Count; i++)
{
OutRec outRec = m_PolyOuts[i];
if (outRec.polyNode == null) continue;
if (outRec.FirstLeft == null)
polytree.AddChild(outRec.polyNode);
else
outRec.FirstLeft.polyNode.AddChild(outRec.polyNode);
}
}
//------------------------------------------------------------------------------
public bool Execute(ClipType clipType, PolyTree polytree)
{
return Execute(clipType, polytree,
PolyFillType.pftEvenOdd, PolyFillType.pftEvenOdd);
}
//------------------------------------------------------------------------------
public bool Execute(ClipType clipType, PolyTree polytree,
PolyFillType subjFillType, PolyFillType clipFillType)
{
if (m_ExecuteLocked) return false;
m_ExecuteLocked = true;
m_SubjFillType = subjFillType;
m_ClipFillType = clipFillType;
m_ClipType = clipType;
m_UsingPolyTree = true;
bool succeeded = ExecuteInternal();
//build the return polygons ...
if (succeeded) BuildResult2(polytree);
m_ExecuteLocked = false;
return succeeded;
}