/// <summary>
/// Tests whether the envelopes of two chain sections overlap (intersect).
/// </summary>
/// <returns><c>true</c> if the section envelopes overlap</returns>
private bool Overlaps(
int start0, int end0,
MonotoneChainEdge mce,
int start1, int end1)
{
return(Envelope.Intersects(pts[start0], pts[end0], mce.pts[start1], mce.pts[end1]));
}
/// <summary>
///
/// </summary>
/// <param name="mce"></param>
/// <param name="si"></param>
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);
}
}
}
/// <summary>
///
/// </summary>
/// <param name="edge"></param>
/// <param name="edgeSet"></param>
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));
}
}
/// <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)
{
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.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="mce"></param>
/// <param name="si"></param>
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);
}
/// <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)
{
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.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="chainIndex0"></param>
/// <param name="mce"></param>
/// <param name="chainIndex1"></param>
/// <param name="si"></param>
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);
}
/// <summary>
///
/// </summary>
/// <param name="chainIndex0"></param>
/// <param name="mce"></param>
/// <param name="chainIndex1"></param>
/// <param name="si"></param>
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);
}