/// <summary>Static method to construct the convex hull from an array of points.</summary>
/// <remarks>
/// Static method to construct the convex hull from an array of points. The
/// out_convex_hull array will be populated with the subset of index
/// positions which contribute to the convex hull.
/// Returns the number of points in the convex hull.
/// \param points The points used to create the convex hull.
/// \param count The number of points in the input Point2D array.
/// \param out_convex_hull An index array allocated by the user at least as big as the size of the input points array.
/// </remarks>
internal static int Construct(com.epl.geometry.Point2D[] points, int count, int[] out_convex_hull)
{
com.epl.geometry.ConvexHull convex_hull = new com.epl.geometry.ConvexHull(points, count);
int t0 = 0;
int tm = 1;
com.epl.geometry.Point2D pt_0 = points[t0];
while (tm < count && points[tm].IsEqual(pt_0, com.epl.geometry.NumberUtils.DoubleEps()))
{
tm++;
}
// We don't want to close the gap between t0 and tm.
convex_hull.m_tree_hull.AddElement(t0, -1);
if (tm < count)
{
convex_hull.m_tree_hull.AddBiggestElement(tm, -1);
for (int tp = tm + 1; tp < count; tp++)
{
// Dynamically insert into the current convex hull.
com.epl.geometry.Point2D pt_p = points[tp];
int p = convex_hull.TreeHull_(pt_p);
if (p != -1)
{
convex_hull.m_tree_hull.SetElement(p, tp);
}
}
}
// reset the place holder to the point index.
// Extracts the convex hull from the tree. Reading the tree in order from first to last is the resulting convex hull.
int out_count = 0;
for (int i = convex_hull.m_tree_hull.GetFirst(-1); i != -1; i = convex_hull.m_tree_hull.GetNext(i))
{
out_convex_hull[out_count++] = convex_hull.m_tree_hull.GetElement(i);
}
return(out_count);
}
/// <summary>Static method to construct the convex hull of a Multi_vertex_geometry.</summary>
/// <remarks>
/// Static method to construct the convex hull of a Multi_vertex_geometry.
/// Returns a Geometry.
/// \param mvg The geometry used to create the convex hull.
/// </remarks>
internal static com.epl.geometry.Geometry Construct(com.epl.geometry.MultiVertexGeometry mvg)
{
if (mvg.IsEmpty())
{
return(new com.epl.geometry.Polygon(mvg.GetDescription()));
}
com.epl.geometry.MultiVertexGeometryImpl mvg_impl = (com.epl.geometry.MultiVertexGeometryImpl)mvg._getImpl();
int N = mvg_impl.GetPointCount();
if (N <= 2)
{
if (N == 1 || mvg_impl.GetXY(0).Equals(mvg_impl.GetXY(1)))
{
com.epl.geometry.Point point = new com.epl.geometry.Point(mvg_impl.GetDescription());
mvg_impl.GetPointByVal(0, point);
return(point);
}
else
{
com.epl.geometry.Point pt = new com.epl.geometry.Point();
com.epl.geometry.Polyline polyline = new com.epl.geometry.Polyline(mvg_impl.GetDescription());
mvg_impl.GetPointByVal(0, pt);
polyline.StartPath(pt);
mvg_impl.GetPointByVal(1, pt);
polyline.LineTo(pt);
return(polyline);
}
}
com.epl.geometry.AttributeStreamOfDbl stream = (com.epl.geometry.AttributeStreamOfDbl)mvg_impl.GetAttributeStreamRef(com.epl.geometry.VertexDescription.Semantics.POSITION);
com.epl.geometry.ConvexHull convex_hull = new com.epl.geometry.ConvexHull(stream, N);
int t0 = 0;
int tm = 1;
com.epl.geometry.Point2D pt_0 = new com.epl.geometry.Point2D();
com.epl.geometry.Point2D pt_m = new com.epl.geometry.Point2D();
com.epl.geometry.Point2D pt_p = new com.epl.geometry.Point2D();
stream.Read(t0 << 1, pt_0);
while (true)
{
if (tm >= N)
{
break;
}
stream.Read(tm << 1, pt_m);
if (!pt_m.IsEqual(pt_0, com.epl.geometry.NumberUtils.DoubleEps()))
{
break;
}
tm++;
}
// We don't want to close the gap between t0 and tm.
convex_hull.m_tree_hull.AddElement(t0, -1);
if (tm < N)
{
convex_hull.m_tree_hull.AddBiggestElement(tm, -1);
for (int tp = tm + 1; tp < mvg_impl.GetPointCount(); tp++)
{
// Dynamically insert into the current convex hull
stream.Read(tp << 1, pt_p);
int p = convex_hull.TreeHull_(pt_p);
if (p != -1)
{
convex_hull.m_tree_hull.SetElement(p, tp);
}
}
}
// reset the place holder to the point index.
// Extracts the convex hull from the tree. Reading the tree in order from first to last is the resulting convex hull.
com.epl.geometry.VertexDescription description = mvg_impl.GetDescription();
bool b_has_attributes = (description.GetAttributeCount() > 1);
int point_count = convex_hull.m_tree_hull.Size(-1);
com.epl.geometry.Geometry hull;
if (point_count >= 2)
{
if (point_count >= 3)
{
hull = new com.epl.geometry.Polygon(description);
}
else
{
hull = new com.epl.geometry.Polyline(description);
}
com.epl.geometry.MultiPathImpl hull_impl = (com.epl.geometry.MultiPathImpl)hull._getImpl();
hull_impl.AddPath((com.epl.geometry.Point2D[])null, 0, true);
com.epl.geometry.Point point = null;
if (b_has_attributes)
{
point = new com.epl.geometry.Point();
}
for (int i = convex_hull.m_tree_hull.GetFirst(-1); i != -1; i = convex_hull.m_tree_hull.GetNext(i))
{
if (b_has_attributes)
{
mvg_impl.GetPointByVal(convex_hull.m_tree_hull.GetElement(i), point);
hull_impl.InsertPoint(0, -1, point);
}
else
{
stream.Read(convex_hull.m_tree_hull.GetElement(i) << 1, pt_p);
hull_impl.InsertPoint(0, -1, pt_p);
}
}
}
else
{
System.Diagnostics.Debug.Assert((point_count == 1));
if (b_has_attributes)
{
com.epl.geometry.Point point = new com.epl.geometry.Point(description);
mvg_impl.GetPointByVal(convex_hull.m_tree_hull.GetElement(convex_hull.m_tree_hull.GetFirst(-1)), point);
hull = point;
}
else
{
stream.Read(convex_hull.m_tree_hull.GetElement(convex_hull.m_tree_hull.GetFirst(-1)) << 1, pt_p);
hull = new com.epl.geometry.Point(pt_p);
}
}
return(hull);
}