public bool MoveNext()
{
while (++edge_id_ >= num_edges_)
{
if (++shape_id_ >= index_.NumShapeIds())
{
break;
}
var shape = index_.Shape(shape_id_);
num_edges_ = (shape == null) ? 0 : shape.NumEdges();
edge_id_ = -1;
}
return(!Done());
}
// Returns the total area of all polygons in the index. Returns zero if no
// polygons are present. This method has good relative accuracy for both very
// large and very small regions. Note that the result may exceed 4*Pi if the
// index contains overlapping polygons.
//
// All edges are modeled as spherical geodesics. The result can be converted
// to an area on the Earth's surface (with a worst-case error of 0.900% near
// the poles) using the functions in s2earth.h.
public static double GetArea(S2ShapeIndex index)
{
double area = 0;
for (int i = 0; i < index.NumShapeIds(); ++i)
{
var shape = index.Shape(i);
if (shape != null)
{
area += S2.GetArea(shape);
}
}
return(area);
}
// Returns the total perimeter of all polygons in the index (including both
// "shells" and "holes"). Returns zero if no polygons are present.
//
// All edges are modeled as spherical geodesics. The result can be converted
// to a distance on the Earth's surface (with a worst-case error of 0.562%
// near the equator) using the functions in s2earth.h.
public static S1Angle GetPerimeter(S2ShapeIndex index)
{
var perimeter = S1Angle.Zero;
for (int i = 0; i < index.NumShapeIds(); ++i)
{
var shape = index.Shape(i);
if (shape != null)
{
perimeter += S2.GetPerimeter(shape);
}
}
return(perimeter);
}
// Returns the total length of all polylines in the index. Returns zero if no
// polylines are present.
//
// All edges are modeled as spherical geodesics. The result can be converted
// to a distance on the Earth's surface (with a worst-case error of 0.562%
// near the equator) using the functions in s2earth.h.
public static S1Angle GetLength(S2ShapeIndex index)
{
var length = S1Angle.Zero;
for (int i = 0; i < index.NumShapeIds(); ++i)
{
var shape = index.Shape(i);
if (shape != null)
{
length += S2.GetLength(shape);
}
}
return(length);
}
// Returns the number of points (objects of dimension zero) in the index.
// Note that polyline and polygon vertices are *not* included in this count.
public static int GetNumPoints(S2ShapeIndex index)
{
int count = 0;
for (int i = 0; i < index.NumShapeIds(); ++i)
{
var shape = index.Shape(i);
if (shape != null && shape.Dimension() == 0)
{
count += shape.NumEdges();
}
}
return(count);
}
// Returns the maximum dimension of any shape in the index. Returns -1 if the
// index does not contain any shapes.
//
// Note that the dimension does *not* depend on whether the shapes in the
// index contain any points; for example, the dimension of an empty point set
// is 0, and the dimension of an empty polygon is 2.
public static int GetDimension(S2ShapeIndex index)
{
int dim = -1;
for (int i = 0; i < index.NumShapeIds(); ++i)
{
var shape = index.Shape(i);
if (shape != null)
{
dim = Math.Max(dim, shape.Dimension());
}
}
return(dim);
}
public VisitIntersectingShapesTest(S2ShapeIndex index)
{
index_ = index;
iter_ = new(index);
region_ = new(index);
// Create an S2ShapeIndex for each shape in the original index, so that we
// can use MayIntersect() and Contains() to determine the status of
// individual shapes.
for (int s = 0; s < index_.NumShapeIds(); ++s)
{
var shape_index = new MutableS2ShapeIndex();
shape_index.Add(new S2WrappedShape(index_.Shape(s)));
shape_indexes_.Add(shape_index);
}
}
// Returns the centroid of all shapes whose dimension is maximal within the
// index, multiplied by the measure of those shapes. For example, if the
// index contains points and polylines, then the result is defined as the
// centroid of the polylines multiplied by the total length of those
// polylines. The points would be ignored when computing the centroid.
//
// The measure of a given shape is defined as follows:
//
// - For dimension 0 shapes, the measure is shape.num_edges().
// - For dimension 1 shapes, the measure is GetLength(shape).
// - For dimension 2 shapes, the measure is GetArea(shape).
//
// Note that the centroid is not unit length, so you may need to call
// Normalize() before passing it to other S2 functions. Note that this
// function returns (0, 0, 0) if the index contains no geometry.
//
// The centroid is scaled by the total measure of the shapes for two reasons:
// (1) it is cheaper to compute this way, and (2) this makes it easier to
// compute the centroid of a collection of shapes (since the individual
// centroids can simply be summed).
public static S2Point GetCentroid(S2ShapeIndex index)
{
int dim = GetDimension(index);
var centroid = S2Point.Empty;
for (int i = 0; i < index.NumShapeIds(); ++i)
{
var shape = index.Shape(i);
if (shape != null && shape.Dimension() == dim)
{
centroid += S2.GetCentroid(shape);
}
}
return(centroid);
}
/// <summary>
/// Verifies that two S2ShapeIndexes have identical contents (including all the
/// S2Shapes in both indexes).
/// </summary>
public static void ExpectEqual(S2ShapeIndex a, S2ShapeIndex b)
{
// Check that both indexes have identical shapes.
Assert.True(a.NumShapeIds() == b.NumShapeIds());
for (int shape_id = 0; shape_id < a.NumShapeIds(); ++shape_id)
{
var a_shape = a.Shape(shape_id);
var b_shape = b.Shape(shape_id);
if (a_shape == null || b_shape == null)
{
Assert.True(a_shape == b_shape);
}
else
{
Assert.True(a_shape.Id == b_shape.Id);
Assert.True(a_shape == b_shape);
}
}
// Check that both indexes have identical cell contents.
var a_it = a.GetNewEnumerator();
var b_it = b.GetNewEnumerator();
var aHasNext = a_it.MoveNext();
var bHasNext = b_it.MoveNext();
while (aHasNext && bHasNext)
{
Assert.True(a_it.Current.Item1 == b_it.Current.Item1);
var a_cell = a_it.Current.Item2;
var b_cell = b_it.Current.Item2;
Assert.True(a_cell.NumClipped() == b_cell.NumClipped());
for (var i = 0; i < a_cell.NumClipped(); ++i)
{
var a_clipped = a_cell.Clipped(i);
var b_clipped = b_cell.Clipped(i);
Assert.True(a_clipped.ShapeId == b_clipped.ShapeId);
Assert.True(a_clipped.ContainsCenter == b_clipped.ContainsCenter);
Assert.True(a_clipped.NumEdges == b_clipped.NumEdges);
for (int j = 0; j < a_clipped.NumEdges; ++j)
{
Assert.True(a_clipped.Edge(j) == b_clipped.Edge(j));
}
}
aHasNext = a_it.MoveNext();
bHasNext = b_it.MoveNext();
}
Assert.True(!bHasNext);
// Spot-check the other iterator methods. (We know that both indexes have
// the same contents, so any differences are due to implementation bugs.)
a_it.Reset();
b_it.Reset();
a_it.MoveNext();
b_it.MoveNext();
Assert.True(a_it.Current.Item1 == b_it.Current.Item1);
aHasNext = a_it.MoveNext();
bHasNext = b_it.MoveNext();
if (aHasNext)
{
Assert.True(a_it.Current.Item1 == b_it.Current.Item1);
Assert.True(aHasNext == bHasNext);
// Assert.True(a_it.MovePrevious());
// Assert.True(b_it.MovePrevious());
Assert.True(a_it.Current.Item1 == b_it.Current.Item1);
}
// Assert.False(a_it.MovePrevious());
// Assert.False(b_it.MovePrevious());
// a_it.Finish();
// b_it.Finish();
// Assert.True(a_it.id() == b_it.id());
// a_it.Seek(a_it.id().Next);
// b_it.Seek(b_it.id().Next);
// Assert.True(a_it.id() == b_it.id());
}
