/// <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);
}
/// <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);
}
}
}
/// <summary>
///
/// </summary>
/// <param name="start0"></param>
/// <param name="end0"></param>
/// <param name="mce"></param>
/// <param name="start1"></param>
/// <param name="end1"></param>
/// <param name="ei"></param>
private void ComputeIntersectsForChain(int start0, int end0, MonotoneChainEdge mce, int start1, int end1, SegmentIntersector ei)
{
ICoordinate p00 = pts[start0];
ICoordinate p01 = pts[end0];
ICoordinate p10 = mce.pts[start1];
ICoordinate p11 = mce.pts[end1];
// terminating condition for the recursion
if (end0 - start0 == 1 && end1 - start1 == 1)
{
ei.AddIntersections(e, start0, mce.e, start1);
return;
}
// nothing to do if the envelopes of these chains don't overlap
env1.Init(p00, p01);
env2.Init(p10, p11);
if (!env1.Intersects(env2))
{
return;
}
// the chains overlap, so split each in half and iterate (binary search)
int mid0 = (start0 + end0) / 2;
int mid1 = (start1 + end1) / 2;
// check terminating conditions before recursing
if (start0 < mid0)
{
if (start1 < mid1)
{
ComputeIntersectsForChain(start0, mid0, mce, start1, mid1, ei);
}
if (mid1 < end1)
{
ComputeIntersectsForChain(start0, mid0, mce, mid1, end1, ei);
}
}
if (mid0 < end0)
{
if (start1 < mid1)
{
ComputeIntersectsForChain(mid0, end0, mce, start1, mid1, ei);
}
if (mid1 < end1)
{
ComputeIntersectsForChain(mid0, end0, mce, mid1, end1, ei);
}
}
}
/// <summary>
///
/// </summary>
/// <param name="ss"></param>
/// <param name="si"></param>
public void ComputeIntersections(SweepLineSegment ss, SegmentIntersector si)
{
si.AddIntersections(edge, ptIndex, ss.edge, ss.ptIndex);
}
/// <summary>
///
/// </summary>
/// <param name="ss"></param>
/// <param name="si"></param>
public void ComputeIntersections(SweepLineSegment ss, SegmentIntersector si)
{
si.AddIntersections(edge, ptIndex, ss.edge, ss.ptIndex);
}
/// <summary>
///
/// </summary>
/// <param name="start0"></param>
/// <param name="end0"></param>
/// <param name="mce"></param>
/// <param name="start1"></param>
/// <param name="end1"></param>
/// <param name="ei"></param>
private void ComputeIntersectsForChain( int start0, int end0, MonotoneChainEdge mce, int start1, int end1, SegmentIntersector ei)
{
ICoordinate p00 = pts[start0];
ICoordinate p01 = pts[end0];
ICoordinate p10 = mce.pts[start1];
ICoordinate p11 = mce.pts[end1];
// terminating condition for the recursion
if (end0 - start0 == 1 && end1 - start1 == 1)
{
ei.AddIntersections(e, start0, mce.e, start1);
return;
}
// nothing to do if the envelopes of these chains don't overlap
env1.Init(p00, p01);
env2.Init(p10, p11);
if (!env1.Intersects(env2))
return;
// the chains overlap, so split each in half and iterate (binary search)
int mid0 = (start0 + end0) / 2;
int mid1 = (start1 + end1) / 2;
// check terminating conditions before recursing
if (start0 < mid0)
{
if (start1 < mid1)
ComputeIntersectsForChain(start0, mid0, mce, start1, mid1, ei);
if (mid1 < end1)
ComputeIntersectsForChain(start0, mid0, mce, mid1, end1, ei);
}
if (mid0 < end0)
{
if (start1 < mid1)
ComputeIntersectsForChain(mid0, end0, mce, start1, mid1, ei);
if (mid1 < end1)
ComputeIntersectsForChain(mid0, end0, mce, mid1, end1, ei);
}
}
