private void ComputeIntersectsForChain(int start0, int end0,
MonotoneChainEdge mce, int start1, int end1, SegmentIntersector ei)
{
Coordinate p00 = pts[start0];
Coordinate p01 = pts[end0];
Coordinate p10 = mce.pts[start1];
Coordinate 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.Initialize(p00, p01);
env2.Initialize(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;
// Assert: mid != start or end (since we checked above for end - start <= 1)
// 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);
}
}
}
public void ComputeIntersectsForChain(int chainIndex0,
MonotoneChainEdge mce, int chainIndex1, SegmentIntersector si)
{
ComputeIntersectsForChain(startIndex[chainIndex0],
startIndex[chainIndex0 + 1], mce, mce.startIndex[chainIndex1],
mce.startIndex[chainIndex1 + 1], si);
}
public void ComputeIntersections(MonotoneChain mc,
SegmentIntersector si)
{
this.mce.ComputeIntersectsForChain(chainIndex,
mc.mce, mc.chainIndex, si);
}
/// <summary>
/// Computes all mutual intersections between two sets of edges.
/// </summary>
/// <param name="edges0">A list of edges to test for intersections.</param>
/// <param name="edges1">A list of edges to test for intersections.</param>
/// <param name="si">The SegmentIntersector to use.</param>
public abstract void ComputeIntersections(EdgeCollection edges0,
EdgeCollection edges1, SegmentIntersector si);
/// <summary> Computes all self-intersections between edges in a set of edges,
/// allowing client to choose whether self-intersections are computed.
/// </summary>
/// <param name="edges">A list of edges to test for intersections.</param>
/// <param name="si">The SegmentIntersector to use.</param>
/// <param name="testAllSegments">true if self-intersections are to be tested as well
/// </param>
public abstract void ComputeIntersections(EdgeCollection edges,
SegmentIntersector si, bool testAllSegments);
public void ComputeIntersections(SweepLineSegment ss,
SegmentIntersector si)
{
si.AddIntersections(edge, ptIndex, ss.edge, ss.ptIndex);
}
