/// <summary>
/// Given a polygon defined by an outer ring with one or more inner rings (holes), return a single list of points representing
/// a polygon with a hole added to it. The added hole is removed from <paramref name="innerRings"/>.
/// </summary>
/// <param name="outerRing">A list of Cartographic points defining the outer polygon.</param>
/// <param name="innerRings">A list of lists of Cartographic points, each list defining a "hole" in the outer polygon.</param>
/// <returns>A single list of Cartographic points defining the polygon, including the eliminated inner ring.</returns>
public static List <Cartographic> EliminateHole(List <Cartographic> outerRing, List <List <Cartographic> > innerRings)
{
// Convert from LLA -> XYZ and project points onto a tangent plane to find the mutually visible vertex.
List <Cartesian> cartesianOuterRing = new List <Cartesian>();
foreach (Cartographic point in outerRing)
{
cartesianOuterRing.Add(Ellipsoid.Wgs84.ToCartesian(point));
}
var windingOrder = GetWindingOrder(cartesianOuterRing);
List <List <Cartesian> > cartesianInnerRings = new List <List <Cartesian> >();
for (int i = 0; i < innerRings.Count; ++i)
{
var ring = innerRings[i];
List <Cartesian> cartesianInnerRing = new List <Cartesian>();
foreach (Cartographic point in ring)
{
cartesianInnerRing.Add(Ellipsoid.Wgs84.ToCartesian(point));
}
var innerWindingOrder = GetWindingOrder(cartesianInnerRing);
if (innerWindingOrder == windingOrder)
{
ring.Reverse();
cartesianInnerRing.Reverse();
}
cartesianInnerRings.Add(cartesianInnerRing);
}
EllipsoidTangentPlane tangentPlane = new EllipsoidTangentPlane(Ellipsoid.Wgs84, cartesianOuterRing);
cartesianOuterRing = (List <Cartesian>)(tangentPlane.ComputePositionsOnPlane(cartesianOuterRing));
for (int i = 0; i < cartesianInnerRings.Count; i++)
{
cartesianInnerRings[i] = (List <Cartesian>)(tangentPlane.ComputePositionsOnPlane(cartesianInnerRings[i]));
}
int visibleVertexIndex = GetMutuallyVisibleVertexIndex(cartesianOuterRing, cartesianInnerRings);
int innerRingIndex = GetRightmostRingIndex(cartesianInnerRings);
int innerRingVertexIndex = GetRightmostVertexIndex(cartesianInnerRings[innerRingIndex]);
List <Cartographic> innerRing = innerRings[innerRingIndex];
List <Cartographic> newPolygonVertices = new List <Cartographic>();
for (int i = 0; i < outerRing.Count; i++)
{
newPolygonVertices.Add(outerRing[i]);
}
List <Cartographic> holeVerticesToAdd = new List <Cartographic>();
// If the rightmost inner vertex is not the starting and ending point of the ring,
// then some other point is duplicated in the inner ring and should be skipped once.
if (innerRingVertexIndex != 0)
{
for (int j = 0; j <= innerRing.Count; j++)
{
int index = (j + innerRingVertexIndex) % innerRing.Count;
if (index != 0)
{
holeVerticesToAdd.Add(innerRing[index]);
}
}
}
else
{
for (int j = 0; j < innerRing.Count; j++)
{
holeVerticesToAdd.Add(innerRing[(j + innerRingVertexIndex) % innerRing.Count]);
}
}
int lastVisibleVertexIndex = newPolygonVertices.FindLastIndex(delegate(Cartographic point)
{
return(point.Equals(outerRing[visibleVertexIndex]));
});
holeVerticesToAdd.Add(outerRing[lastVisibleVertexIndex]);
newPolygonVertices.InsertRange(lastVisibleVertexIndex + 1, holeVerticesToAdd);
innerRings.RemoveAt(innerRingIndex);
return(newPolygonVertices);
}
/// <summary>
/// Given a polygon defined by an outer ring with one or more inner rings (holes), return a single list of points representing
/// a polygon with a hole added to it. The added hole is removed from <paramref name="innerRings"/>.
/// </summary>
/// <param name="outerRing">A list of Cartographic points defining the outer polygon.</param>
/// <param name="innerRings">A list of lists of Cartographic points, each list defining a "hole" in the outer polygon.</param>
/// <returns>A single list of Cartographic points defining the polygon, including the eliminated inner ring.</returns>
public static List<Cartographic> EliminateHole(List<Cartographic> outerRing, List<List<Cartographic>> innerRings)
{
// Convert from LLA -> XYZ and project points onto a tangent plane to find the mutually visible vertex.
List<Cartesian> cartesianOuterRing = new List<Cartesian>();
foreach (Cartographic point in outerRing)
{
cartesianOuterRing.Add(Ellipsoid.Wgs84.ToCartesian(point));
}
var windingOrder = GetWindingOrder(cartesianOuterRing);
List<List<Cartesian>> cartesianInnerRings = new List<List<Cartesian>>();
for(int i = 0; i < innerRings.Count; ++i)
{
var ring = innerRings[i];
List<Cartesian> cartesianInnerRing = new List<Cartesian>();
foreach (Cartographic point in ring)
{
cartesianInnerRing.Add(Ellipsoid.Wgs84.ToCartesian(point));
}
var innerWindingOrder = GetWindingOrder(cartesianInnerRing);
if (innerWindingOrder == windingOrder)
{
ring.Reverse();
cartesianInnerRing.Reverse();
}
cartesianInnerRings.Add(cartesianInnerRing);
}
EllipsoidTangentPlane tangentPlane = new EllipsoidTangentPlane(Ellipsoid.Wgs84, cartesianOuterRing);
cartesianOuterRing = (List<Cartesian>)(tangentPlane.ComputePositionsOnPlane(cartesianOuterRing));
for (int i = 0; i < cartesianInnerRings.Count; i++)
{
cartesianInnerRings[i] = (List<Cartesian>)(tangentPlane.ComputePositionsOnPlane(cartesianInnerRings[i]));
}
int visibleVertexIndex = GetMutuallyVisibleVertexIndex(cartesianOuterRing, cartesianInnerRings);
int innerRingIndex = GetRightmostRingIndex(cartesianInnerRings);
int innerRingVertexIndex = GetRightmostVertexIndex(cartesianInnerRings[innerRingIndex]);
List<Cartographic> innerRing = innerRings[innerRingIndex];
List<Cartographic> newPolygonVertices = new List<Cartographic>();
for (int i = 0; i < outerRing.Count; i++)
{
newPolygonVertices.Add(outerRing[i]);
}
List<Cartographic> holeVerticesToAdd = new List<Cartographic>();
// If the rightmost inner vertex is not the starting and ending point of the ring,
// then some other point is duplicated in the inner ring and should be skipped once.
if (innerRingVertexIndex != 0)
{
for (int j = 0; j <= innerRing.Count; j++)
{
int index = (j + innerRingVertexIndex) % innerRing.Count;
if (index != 0)
{
holeVerticesToAdd.Add(innerRing[index]);
}
}
}
else
{
for (int j = 0; j < innerRing.Count; j++)
{
holeVerticesToAdd.Add(innerRing[(j + innerRingVertexIndex) % innerRing.Count]);
}
}
int lastVisibleVertexIndex = newPolygonVertices.FindLastIndex(delegate(Cartographic point)
{
return point.Equals(outerRing[visibleVertexIndex]);
});
holeVerticesToAdd.Add(outerRing[lastVisibleVertexIndex]);
newPolygonVertices.InsertRange(lastVisibleVertexIndex + 1, holeVerticesToAdd);
innerRings.RemoveAt(innerRingIndex);
return newPolygonVertices;
}