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);
}
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 ComputeIntersects(MonotoneChainEdge mce,
SegmentIntersector si)
{
for (int i = 0; i < startIndex.Length - 1; i++)
{
for (int j = 0; j < mce.startIndex.Length - 1; j++)
{
ComputeIntersectsForChain(i, mce, j, si);
}
}
}
private void Add(Edge edge, object edgeSet)
{
MonotoneChainEdge mce = edge.MonotoneChainEdge;
int[] startIndex = mce.StartIndexes;
for (int i = 0; i < startIndex.Length - 1; i++)
{
MonotoneChain mc = new MonotoneChain(mce, i);
SweepLineEvent insertEvent = new SweepLineEvent(edgeSet, mce.GetMinX(i), null, mc);
events.Add(insertEvent);
events.Add(new SweepLineEvent(edgeSet, mce.GetMaxX(i), insertEvent, mc));
}
}
public MonotoneChain(MonotoneChainEdge mce, int chainIndex)
{
this.mce = mce;
this.chainIndex = chainIndex;
}