private Point CreateScanSegment(Point start, BasicObstacleSide side, double weight)
{
var end = ScanLineIntersectSide(start, side);
if (start != end)
{
this.parallelSegmentVector.CreateScanSegment(start, end, weight, CurrentGroupBoundaryCrossingMap.GetOrderedListBetween(start, end));
}
return(end);
}
// Return value is whether or not we added a new segment.
bool AddSegment(Point start, Point end, Obstacle eventObstacle
, BasicObstacleSide lowNborSide, BasicObstacleSide highNborSide
, SweepEvent action, double weight)
{
DevTraceInfoVgGen(1, "Adding Segment [{0} -> {1} {2}] weight {3}", start, end, weight);
DevTraceInfoVgGen(2, " side {0}", lowNborSide);
DevTraceInfoVgGen(2, " -> side {0}", highNborSide);
if (PointComparer.Equal(start, end))
{
return(false);
}
// See if the new segment subsumes or can be subsumed by the last one. gbcList may be null.
PointAndCrossingsList gbcList = CurrentGroupBoundaryCrossingMap.GetOrderedListBetween(start, end);
bool extendStart, extendEnd;
bool wasSubsumed = ScanSegment.Subsume(ref hintScanSegment, start, end, weight, gbcList, ScanDirection
, ParallelScanSegments, out extendStart, out extendEnd);
if (!wasSubsumed)
{
Debug.Assert((weight != ScanSegment.ReflectionWeight) || (ParallelScanSegments.Find(start, end) == null),
"Reflection segments already in the ScanSegmentTree should should have been detected before calling AddSegment");
hintScanSegment = ParallelScanSegments.InsertUnique(new ScanSegment(start, end, weight, gbcList)).Item;
}
else if (weight == ScanSegment.ReflectionWeight)
{
// Do not continue this; it is probably a situation where a side is at a tiny angle from the axis,
// resulting in an initial reflection segment that is parallel and very close to the extreme-vertex-derived
// segment, so as the staircase progresses they eventually converge due to floating-point rounding.
// See RectilinearFilesTest.ReflectionStaircasesConverge.
return(false);
}
// Do reflections only if the new segment is not overlapped.
if (ScanSegment.OverlappedWeight != weight)
{
// If these fire, it's probably an indication that isOverlapped is not correctly set
// and one of the neighbors is an OverlapSide from CreateScanSegments.
Debug.Assert(lowNborSide is HighObstacleSide, "lowNbor is not HighObstacleSide");
Debug.Assert(highNborSide is LowObstacleSide, "highNbor is not LowObstacleSide");
// If we are closing the obstacle then the initial Obstacles of the reflections (the ones it
// will bounce between) are the opposite neighbors. Otherwise, the OpenVertexEvent obstacle
// is the ReflectionEvent initial obstacle.
if (action is CloseVertexEvent)
{
// If both neighbor sides reflect upward, they can't intersect, so we don't need
// to store a lookahead site (if neither reflect upward, StoreLookaheadSite no-ops).
if (!SideReflectsUpward(lowNborSide) || !SideReflectsUpward(highNborSide))
{
// Try to store both; only one will "take" (for the upward-reflecting side).
// The initial Obstacle is the opposite neighbor.
if (extendStart)
{
this.StoreLookaheadSite(highNborSide.Obstacle, lowNborSide, start, wantExtreme: false);
}
if (extendEnd)
{
this.StoreLookaheadSite(lowNborSide.Obstacle, highNborSide, end, wantExtreme: false);
}
}
}
else
{
if (extendStart)
{
StoreLookaheadSite(eventObstacle, LowNeighborSides.GroupSideInterveningBeforeLowNeighbor, lowNborSide, start);
}
if (extendEnd)
{
StoreLookaheadSite(eventObstacle, HighNeighborSides.GroupSideInterveningBeforeHighNeighbor, highNborSide, end);
}
}
}
DevTraceInfoVgGen(2, "HintScanSegment {0}{1}", hintScanSegment, wasSubsumed ? " (subsumed)" : "");
DevTrace_DumpScanSegmentsDuringAdd(3);
return(true);
}