internal RBNode <BasicObstacleSide> Find(BasicObstacleSide side)
{
// Sides that start after the current position cannot be in the scanline.
if (-1 == scanDirection.ComparePerpCoord(this.linePositionAtLastInsertOrRemove, side.Start))
{
return(null);
}
return(SideTree.Find(side));
}
/// <summary>
/// For ordering events in the event list.
/// Assuming vertical sweep (sweeping up from bottom, scanning horizontally) then order events
/// first by lowest Y coord, then by lowest X coord (thus assuming we use Cartesian coordinates
/// (negative is downward == bottom).
/// </summary>
/// <param name="lhs"></param>
/// <param name="rhs"></param>
/// <returns></returns>
public int Compare(SweepEvent lhs, SweepEvent rhs)
{
if (lhs == rhs)
{
return(0);
}
if (lhs == null)
{
return(-1);
}
if (rhs == null)
{
return(1);
}
// First see if it's at the same scanline level (perpendicular coordinate).
int cmp = scanDirection.ComparePerpCoord(lhs.Site, rhs.Site);
if (0 == cmp)
{
// Event sites are at the same scanline level. Make sure that any reflection events are lowest (come before
// any side events, which could remove the side the reflection event was queued for). We may have two
// reflection events at same coordinate, because we enqueue in two situations: when a side is opened,
// and when a side that is within that side's scanline-parallel span is closed.
bool lhsIsNotReflection = !(lhs is BasicReflectionEvent);
bool rhsIsNotReflection = !(rhs is BasicReflectionEvent);
cmp = lhsIsNotReflection.CompareTo(rhsIsNotReflection);
// If the scanline-parallel coordinate is the same these events are at the same point.
if (0 == cmp)
{
cmp = scanDirection.CompareScanCoord(lhs.Site, rhs.Site);
}
}
return(cmp);
}
