/**
* Like AssembleLoops, but normalizes all the loops so that they enclose less
* than half the sphere, and then assembles the loops into a polygon.
*
* For this method to succeed, there should be no duplicate edges in the
* input. If this is not known to be true, then the "xor_edges" option should
* be set (which is true by default).
*
* Note that S2Polygons cannot represent arbitrary regions on the sphere,
* because of the limitation that no loop encloses more than half of the
* sphere. For example, an S2Polygon cannot represent a 100km wide band around
* the equator. In such cases, this method will return the *complement* of the
* expected region. So for example if all the world's coastlines were
* assembled, the output S2Polygon would represent the land area (irrespective
* of the input edge or loop orientations).
*/
public bool AssemblePolygon(S2Polygon polygon, System.Collections.Generic.IList <S2Edge> unusedEdges)
{
var loops = new List <S2Loop>();
var success = AssembleLoops(loops, unusedEdges);
// If edges are undirected, then all loops are already CCW. Otherwise we
// need to make sure the loops are normalized.
if (!_options.UndirectedEdges)
{
for (var i = 0; i < loops.Count; ++i)
{
loops[i].Normalize();
}
}
if (_options.Validate && !S2Polygon.IsValidPolygon(loops))
{
if (unusedEdges != null)
{
foreach (var loop in loops)
{
RejectLoop(loop, loop.NumVertices, unusedEdges);
}
}
return(false);
}
polygon.Init(loops);
return(success);
}
