private static bool IsEffectivelyRightOfSplitter(BspSegment splitter, BspSegment segment)
{
Rotation startSide = splitter.ToSide(segment.Start);
if (startSide == Rotation.On)
{
Rotation endSide = splitter.ToSide(segment.End);
Debug.Assert(endSide != Rotation.On, "Splitter and segment are too close to determine sides");
return(endSide == Rotation.Right);
}
return(startSide == Rotation.Right);
}
protected void HandleEndpointIntersectionSplit(BspSegment splitter, BspSegment segmentToSplit, Endpoint endpoint)
{
// We know that the endpoint argument is the vertex that was
// intersected by the splitter. This means the other endpoint is
// on the left or the right side of the splitter, so we'll use
// that 'opposite' endpoint to check the side we should place the
// segment on.
BspVertex oppositeVertex = segmentToSplit.Opposite(endpoint);
Rotation side = splitter.ToSide(oppositeVertex);
Debug.Assert(side != Rotation.On, "Ambiguous split, segment too small to determine splitter side");
if (side == Rotation.Right)
{
States.RightSegments.Add(segmentToSplit);
}
else
{
States.LeftSegments.Add(segmentToSplit);
}
BspVertex vertex = segmentToSplit.VertexFrom(endpoint);
States.CollinearVertices.Add(vertex);
}
protected void HandleNonEndpointIntersectionSplit(BspSegment splitter, BspSegment segmentToSplit, double segmentTime)
{
// Note for the future: If we ever change to using pointers or some
// kind of reference that invalidates on a list resizing (like a
// std::vector in C++), this will lead to undefined behavior since
// it will add new segments and cause them to become dangling.
(BspSegment segA, BspSegment segB) = SegmentAllocator.Split(segmentToSplit, segmentTime);
// Since we split the segment such that the line is:
//
// Seg A | Seg B
// [A]=======o=========[B]
// |
// | <-- Splitter
// X
//
// We can find which side of the splitter the segments are on by
// looking at where [A] or [B] ended up. Since the split causes us
// to know that the middle index is at the first segment's endpoint
// (and the second segment start point), either or of these would
// tell us which side the segment is on... and when we know which
// one is on which side of the splitter, we automatically know the
// other segment from the split is on the other.
Rotation side = splitter.ToSide(segA.Start);
// It may be possible that a split occurs so close to the endpoint
// (by some unfortunate map geometry) which screws up detecting
// which side we are on for the splitting. In such a case, we'll
// try checking both endpoints to see if this is the case and make
// our decision accordingly.
if (side == Rotation.On)
{
Log.Warn("Very tight endpoint split perform with segment {0}", segmentToSplit);
Rotation otherSide = splitter.ToSide(segmentToSplit.End);
Debug.Assert(otherSide != Rotation.On, "Segment being split is too small to detect which side of the splitter it's on");
side = (otherSide == Rotation.Left ? Rotation.Right : Rotation.Left);
}
if (side == Rotation.Right)
{
States.RightSegments.Add(segA);
States.LeftSegments.Add(segB);
}
else
{
States.LeftSegments.Add(segA);
States.RightSegments.Add(segB);
}
// The reason we know it's the end index of segA is because the
// splitter always has the first seg splitting based on the start.
// A corollary is that this would be equal to segB.getStartIndex()
// since they are equal.
States.CollinearVertices.Add(segA.EndVertex);
if (segmentToSplit.OneSided)
{
JunctionClassifier.AddSplitJunction(segA, segB);
}
}