using System.Collections;
using GeoAPI.Geometries;
namespace GisSharpBlog.NetTopologySuite.GeometriesGraph.Index{
/// <summary>
/// Finds all intersections in one or two sets of edges,
/// using the straightforward method of
/// comparing all segments.
/// This algorithm is too slow for production use, but is useful for testing purposes.
/// </summary>
public class SimpleEdgeSetIntersector : EdgeSetIntersector
{
/// <summary>
///
/// </summary>
public SimpleEdgeSetIntersector() { }
/// <summary>
///
/// </summary>
/// <param name="edges"></param>
/// <param name="si"></param>
/// <param name="testAllSegments"></param>
public override void ComputeIntersections(IList edges, SegmentIntersector si, bool testAllSegments)
{
for (IEnumerator i0 = edges.GetEnumerator(); i0.MoveNext(); )
{
Edge edge0 = (Edge) i0.Current;
for (IEnumerator i1 = edges.GetEnumerator(); i1.MoveNext(); )
{
Edge edge1 = (Edge) i1.Current;
if (testAllSegments || edge0 != edge1)
ComputeIntersects(edge0, edge1, si);
}
}
}
/// <summary>
///
/// </summary>
/// <param name="edges0"></param>
/// <param name="edges1"></param>
/// <param name="si"></param>
public override void ComputeIntersections(IList edges0, IList edges1, SegmentIntersector si)
{
for (IEnumerator i0 = edges0.GetEnumerator(); i0.MoveNext(); )
{
Edge edge0 = (Edge) i0.Current;
for (IEnumerator i1 = edges1.GetEnumerator(); i1.MoveNext(); )
{
Edge edge1 = (Edge) i1.Current;
ComputeIntersects(edge0, edge1, si);
}
}
}
/// <summary>
/// Performs a brute-force comparison of every segment in each Edge.
/// This has n^2 performance, and is about 100 times slower than using
/// monotone chains.
/// </summary>
/// <param name="e0"></param>
/// <param name="e1"></param>
/// <param name="si"></param>
private void ComputeIntersects(Edge e0, Edge e1, SegmentIntersector si)
{
ICoordinate[] pts0 = e0.Coordinates;
ICoordinate[] pts1 = e1.Coordinates;
for (int i0 = 0; i0 < pts0.Length - 1; i0++)
for (int i1 = 0; i1 < pts1.Length - 1; i1++)
si.AddIntersections(e0, i0, e1, i1);
}
}
}
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