/// <summary>
/// Gets the Voronoi cell around a site specified
/// by the origin of a QuadEdge.
/// </summary>
/// <remarks>
/// The userData of the polygon is set to be the <see cref="Coordinate" />
/// of the site. This allows attaching external
/// data associated with the site to this cell polygon.
/// </remarks>
/// <param name="qe">a quadedge originating at the cell site</param>
/// <param name="geomFact">a factory for building the polygon</param>
/// <returns>a polygon indicating the cell extent</returns>
public Polygon GetVoronoiCellPolygon(QuadEdge qe, GeometryFactory geomFact)
{
var cellPts = new List <Coordinate>();
var startQE = qe;
do
{
// Coordinate cc = circumcentre(qe);
// use previously computed circumcentre
var cc = qe.Rot.Orig.Coordinate;
cellPts.Add(cc);
// move to next triangle CW around vertex
qe = qe.OPrev;
} while (qe != startQE);
var coordList = new CoordinateList();
coordList.AddAll(cellPts, false);
coordList.CloseRing();
if (coordList.Count < 4)
{
Debug.WriteLine(coordList);
coordList.Add(coordList[coordList.Count - 1], true);
}
var pts = coordList.ToCoordinateArray();
var cellPoly = geomFact.CreatePolygon(geomFact.CreateLinearRing(pts));
var v = startQE.Orig;
cellPoly.UserData = v.Coordinate;
return(cellPoly);
}
/// <summary>
///
/// </summary>
/// <param name="inputPts"></param>
/// <returns></returns>
private static Coordinate[] ComputeOctRing(Coordinate[] inputPts)
{
var octPts = ComputeOctPts(inputPts);
var coordList = new CoordinateList();
coordList.Add(octPts, false);
// points must all lie in a line
if (coordList.Count < 3)
return null;
coordList.CloseRing();
return coordList.ToCoordinateArray();
}
/// <summary>
///
/// </summary>
/// <param name="inputPts"></param>
/// <returns></returns>
private ICoordinate[] ComputeOctRing(ICoordinate[] inputPts)
{
ICoordinate[] octPts = ComputeOctPts(inputPts);
CoordinateList coordList = new CoordinateList();
coordList.Add(octPts, false);
// points must all lie in a line
if (coordList.Count < 3)
{
return(null);
}
coordList.CloseRing();
return(coordList.ToCoordinateArray());
}
/// <summary>
///
/// </summary>
/// <param name="inputPts"></param>
/// <returns></returns>
private static Coordinate[] ComputeOctRing(Coordinate[] inputPts)
{
Coordinate[] octPts = ComputeOctPts(inputPts);
CoordinateList coordList = new CoordinateList {
{ octPts, false }
};
// points must all lie in a line
if (coordList.Count < 3)
{
return(null);
}
coordList.CloseRing();
return(coordList.ToCoordinateArray());
}
public static Geometry LineToPolygon(Geometry g)
{
if (g is IPolygonal)
{
return(g);
}
// TODO: ensure ring is valid
var ringList = new CoordinateList();
var pts = g.Coordinates;
foreach (var pt in pts)
{
ringList.Add(pt, true);
}
ringList.CloseRing();
var ring = g.Factory.CreateLinearRing(ringList.ToCoordinateArray());
return(g.Factory.CreatePolygon(ring, null));
}
private Coordinate[] GetBoundary(int level, Coordinate origin, double width)
{
double y = origin.Y;
// for all levels beyond 0 need to vertically shift shape by height of one "arm" to centre it
if (level > 0)
{
y += ThirdHeight * width;
}
var p0 = new Coordinate(origin.X, y);
var p1 = new Coordinate(origin.X + width / 2, y + width * HeightFactor);
var p2 = new Coordinate(origin.X + width, y);
AddSide(level, p0, p1);
AddSide(level, p1, p2);
AddSide(level, p2, p0);
_coordList.CloseRing();
return(_coordList.ToCoordinateArray());
}
public void Visit(QuadEdge[] triEdges)
{
_coordList.Clear();
for (int i = 0; i < 3; i++)
{
var v = triEdges[i].Orig;
_coordList.Add(v.Coordinate);
}
if (_coordList.Count > 0)
{
_coordList.CloseRing();
var pts = _coordList.ToCoordinateArray();
if (pts.Length != 4)
{
//CheckTriangleSize(pts);
return;
}
_triCoords.Add(pts);
}
}
/*
* private bool IsInsideEdge(Envelope env, int edgeIndex)
* {
* switch (edgeIndex)
* {
* case ENV_BOTTOM:
* return env.MinY > _clipEnvMinY;
* case ENV_RIGHT:
* return env.MaxX < _clipEnvMaxX;
* case ENV_TOP:
* return env.MaxY < _clipEnvMaxY;
* case ENV_LEFT:
* default:
* return env.MinX > _clipEnvMinX;
* }
* }
*
* private bool IsOutsideEdge(Envelope env, int edgeIndex)
* {
* switch (edgeIndex)
* {
* case ENV_BOTTOM:
* return env.MaxY < _clipEnvMinY;
* case ENV_RIGHT:
* return env.MinX > _clipEnvMaxX;
* case ENV_TOP:
* return env.MinY > _clipEnvMaxY;
* case ENV_LEFT:
* default:
* return env.MaxX < _clipEnvMinX;
* }
* }
*
* Envelope currentCoordsEnv;
*/
/// <summary>
/// Clips ring to a axis-parallel line defined by a single box edge.
/// </summary>
/// <param name="coords">An array of coordinates</param>
/// <param name="edgeIndex">An edge index</param>
/// <returns>The clipped points, or <c>null</c> if all were clipped</returns>
private Coordinate[] ClipRingToBoxEdge(Coordinate[] coords, int edgeIndex)
{
var clipCoords = new CoordinateList();
var p0 = coords[coords.Length - 1];
for (int i = 0; i < coords.Length; i++)
{
var p1 = coords[i];
if (IsInsideEdge(p1, edgeIndex))
{
if (!IsInsideEdge(p0, edgeIndex))
{
var intPt = IntersectionPrecise(p0, p1, edgeIndex);
clipCoords.Add(intPt, false);
//currentCoordsEnv.expandToInclude(intPt);
}
// TODO: avoid copying so much?
var p1Precise = MakePrecise(p1.Copy());
clipCoords.Add(p1Precise, false);
//currentCoordsEnv.expandToInclude(p1Precise);
}
else if (IsInsideEdge(p0, edgeIndex))
{
var intPt = IntersectionPrecise(p0, p1, edgeIndex);
clipCoords.Add(intPt, false);
//currentCoordsEnv.expandToInclude(intPt);
}
// move to next segment
p0 = p1;
}
// check if all points clipped off
if (clipCoords.Count <= 0)
{
return(null);
}
clipCoords.CloseRing();
return(clipCoords.ToCoordinateArray());
}
/// <summary>
/// Gets the Voronoi cell around a site specified
/// by the origin of a QuadEdge.
/// </summary>
/// <remarks>
/// The userData of the polygon is set to be the <see cref="Coordinate" />
/// of the site. This allows attaching external
/// data associated with the site to this cell polygon.
/// </remarks>
/// <param name="qe">a quadedge originating at the cell site</param>
/// <param name="geomFact">a factory for building the polygon</param>
/// <returns>a polygon indicating the cell extent</returns>
public IPolygon GetVoronoiCellPolygon(QuadEdge qe, IGeometryFactory geomFact)
{
var cellPts = new List<Coordinate>();
QuadEdge startQE = qe;
do
{
// Coordinate cc = circumcentre(qe);
// use previously computed circumcentre
Coordinate cc = qe.Rot.Orig.Coordinate;
cellPts.Add(cc);
// move to next triangle CW around vertex
qe = qe.OPrev;
} while (qe != startQE);
var coordList = new CoordinateList();
coordList.AddAll(cellPts, false);
coordList.CloseRing();
if (coordList.Count < 4)
{
#if !PCL
Debug.WriteLine(coordList);
#endif
coordList.Add(coordList[coordList.Count - 1], true);
}
Coordinate[] pts = coordList.ToCoordinateArray();
IPolygon cellPoly = geomFact.CreatePolygon(geomFact.CreateLinearRing(pts), null);
Vertex v = startQE.Orig;
cellPoly.UserData = v.Coordinate;
return cellPoly;
}
