// Called by LowReflectionEvent or HighReflectionEvent ctors, which are called out of
// AddReflectionEvent, which in turn is called by LoadLookaheadIntersections.
// In this case we know the eventObstacle and initialObstacle are the same obstacle (the
// one that the reflected ray bounced off of, to generate the Left/HighReflectionEvent).
internal BasicReflectionEvent(BasicReflectionEvent previousSite, Obstacle reflectingObstacle, Point site)
{
this.InitialObstacle = previousSite.ReflectingObstacle;
this.ReflectingObstacle = reflectingObstacle;
this.site = site;
this.PreviousSite = previousSite;
}
protected override bool InsertParallelReflectionSegment(Point start, Point end, Obstacle eventObstacle,
BasicObstacleSide lowNborSide, BasicObstacleSide highNborSide, BasicReflectionEvent action) {
// See notes in InsertPerpendicularReflectionSegment for comments about an existing segment.
// Here, we call AddSegment which adds the segment and continues the reflection staircase.
if (null != ParallelScanSegments.Find(start, end)) {
return false;
}
return AddSegment(start, end, eventObstacle, lowNborSide, highNborSide, action, ScanSegment.ReflectionWeight);
}
void AddReflectionEvent(BasicReflectionEvent previousSite, BasicObstacleSide side, Point site) {
Debug.Assert(null != scanLine.Find(side), "AddReflectionEvent could not find 'side' in the scanline");
// Add an event that will be drained when a side spanning the scanline-parallel is loaded
// as the sweep moves "up".
var lowSide = side as LowObstacleSide;
if (lowSide != null) {
eventQueue.Enqueue(new LowReflectionEvent(previousSite, lowSide, site));
} else {
eventQueue.Enqueue(new HighReflectionEvent(previousSite, (HighObstacleSide)side, site));
}
}
protected abstract bool InsertParallelReflectionSegment(Point start, Point end, Obstacle eventObstacle,
BasicObstacleSide lowNborSide, BasicObstacleSide highNborSide, BasicReflectionEvent action);
private bool AddParallelReflectionSegment(Obstacle eventObstacle, BasicObstacleSide lowNborSide
, BasicObstacleSide highNborSide, BasicReflectionEvent action) {
// If this is reflecting to a low neighbor, then that intersect is 'start' in the low-to-high
// sequence, and the event site is the end; otherwise we start at the event site and end at
// the high neighbor.
Point intersect = ScanLineIntersectSide(action.Site, lowNborSide ?? highNborSide);
Point start = (null != lowNborSide) ? intersect : action.Site;
Point end = (null != lowNborSide) ? action.Site : intersect;
// Now get the opposite neighbors so AddSegment can continue the reflection chain.
if (null == lowNborSide) {
lowNborSide = scanLine.NextLow(highNborSide).Item;
}
else {
highNborSide = scanLine.NextHigh(lowNborSide).Item;
}
return InsertParallelReflectionSegment(start, end, eventObstacle, lowNborSide, highNborSide, action);
}
// Determine whether the event is valid and do some common processing.
bool AddPerpendicularReflectionSegment(BasicReflectionEvent currentEvent, BasicObstacleSide eventSide, BasicObstacleSide nborSide) {
// If eventSide is null it means we had the wrong side type as a scanline neighbor.
// If another obstacle opened up, then that obstacle (or another intervening one) should have
// drained this reflection event.
Debug.Assert(null != eventSide, "eventSide should not be null");
// Between the time currentEvent was queued and the time we're now processing it, another
// obstacle may have opened between the previousSite and the eventSite, in which case it
// removed currentEvent from the queue already. So currentEvent may be stale. The new
// obstacle may have stored *another* lookahead site with the same scanline-parallel
// coordinate (but higher up perpendicularly). So remove the exact site of currentEvent;
// otherwise the currentEvent could be a stale event with the lower scanline-parallel
// coordinate, and would remove the site from the lookahead list before the "live" event
// looks for it. See RectilinearTests.ReflectionsRemoveInterceptedSite.
if (lookaheadScan.RemoveExact(currentEvent.PreviousSite)) {
Debug.Assert(currentEvent.InitialObstacle == currentEvent.PreviousSite.ReflectingObstacle
, "Inconsistency: currentEvent.InitialObstacle != currentEvent.PreviousSite.ReflectingObstacle");
// ReSharper disable HeuristicUnreachableCode
// ReSharper disable ConditionIsAlwaysTrueOrFalse
if (null == eventSide) {
// We've removed the event so there's nothing else to do.
return false;
}
// ReSharper restore ConditionIsAlwaysTrueOrFalse
// ReSharper restore HeuristicUnreachableCode
// If the two sides intersect ahead of the scanline, we don't want the reflection.
// If the reflecting side is flat, no reflection is done - that's handled by OpenVertexEvent.
Debug.Assert(!IsFlat(eventSide), "Flat sides should not be encountered in reflections");
if (currentEvent.PreviousSite.IsStaircaseStep(currentEvent.ReflectingObstacle)) {
// We need to draw the perpendicular lines here because we may be on the second
// sweep so there won't be a subsequent sweep to draw them. And if we're on the
// second sweep, we may have already loaded this segment as part of a continuation
// of an overlapped segment. Either way, we only want this if we are not on an extreme
// edge of the target obstacle (reflectingObstacle for the perpendicular segment,
// nborSide.Obstacle for the parallel segment). Extreme vertices will generate segments.
// See TestRectilinear.Reflection_Staircase_Stops_At_BoundingBox_Side*.
if (!StaticGraphUtility.PointIsInRectangleInterior(currentEvent.Site, currentEvent.ReflectingObstacle.VisibilityBoundingBox))
{
return false;
}
DevTraceInfoVgGen(1, "Perpendicular Reflection - Adding Segment [{0} -> {1}]", currentEvent.PreviousSite.Site, currentEvent.Site);
DevTraceInfoVgGen(2, " -> side {0}", eventSide); // same indent as AddSegment; eventSide is highNbor
if (!InsertPerpendicularReflectionSegment(currentEvent.PreviousSite.Site, currentEvent.Site)) {
return false;
}
// If the neighbor continues the staircase and the parallel segment would hit a non-extreme point
// on the neighbor, return true and the Low/HighReflectionEvent handler will add the parallel segment.
if ((null != nborSide) && currentEvent.IsStaircaseStep(nborSide.Obstacle)) {
return this.ScanLineCrossesObstacle(currentEvent.Site, nborSide.Obstacle);
}
DevTraceInfoVgGen(1, "Reflection Lookahead site {0} is not an outgoing staircase step; discontinuing", currentEvent.PreviousSite);
}
else {
DevTraceInfoVgGen(1, "Reflection Lookahead site {0} is not an incoming staircase step; discontinuing", currentEvent.PreviousSite);
}
}
else {
DevTraceInfoVgGen(1, "Reflection Lookahead site {0} is no longer in the lookahead table; skipping", currentEvent.PreviousSite);
}
return false;
}
internal HighReflectionEvent(BasicReflectionEvent previousSite, HighObstacleSide targetSide, Point site)
: base (previousSite, targetSide.Obstacle, site) {
this.Side = targetSide;
}
internal LowReflectionEvent(BasicReflectionEvent previousSite, LowObstacleSide targetSide, Point site)
: base(previousSite, targetSide.Obstacle, site)
{
this.Side = targetSide;
}
protected override bool InsertParallelReflectionSegment(Point start, Point end, Obstacle eventObstacle,
BasicObstacleSide lowNborSide, BasicObstacleSide highNborSide, BasicReflectionEvent action)
{
Debug.Assert(false, "base.wantReflections is false in Sparse mode so this should never be called");
// ReSharper disable HeuristicUnreachableCode
return(false);
// ReSharper restore HeuristicUnreachableCode
}
protected override bool InsertParallelReflectionSegment(Point start, Point end, Obstacle eventObstacle,
BasicObstacleSide lowNborSide, BasicObstacleSide highNborSide, BasicReflectionEvent action)
{
// See notes in InsertPerpendicularReflectionSegment for comments about an existing segment.
// Here, we call AddSegment which adds the segment and continues the reflection staircase.
if (null != ParallelScanSegments.Find(start, end))
{
return(false);
}
return(AddSegment(start, end, eventObstacle, lowNborSide, highNborSide, action, ScanSegment.ReflectionWeight));
}
// Called by LowReflectionEvent or HighReflectionEvent ctors, which are called out of
// AddReflectionEvent, which in turn is called by LoadLookaheadIntersections.
// In this case we know the eventObstacle and initialObstacle are the same obstacle (the
// one that the reflected ray bounced off of, to generate the Left/HighReflectionEvent).
internal BasicReflectionEvent(BasicReflectionEvent previousSite, Obstacle reflectingObstacle, Point site) {
this.InitialObstacle = previousSite.ReflectingObstacle;
this.ReflectingObstacle = reflectingObstacle;
this.site = site;
this.PreviousSite = previousSite;
}