// sideWithRange is either the same as sideToQueue, if that side is being loaded by an
// OpenVertexEvent, or is a different side that is just closing.
protected void LoadReflectionEvents(BasicObstacleSide sideToQueue, BasicObstacleSide sideWithRange) {
// If this line reflects upward then it cannot receive rays from below (they would pass
// through its obstacle), and of course a perpendicular lookahead line will never
// intersect a perpendicular side.
if ((null == sideToQueue) || SideReflectsUpward(sideToQueue) || IsPerpendicular(sideToQueue)) {
return;
}
// If there is no overlap in the rectangles along the current axis, there is nothing
// to do. This reduces (but doesn't prevent) duplicate events being loaded.
var bbox1 = new Rectangle(sideToQueue.Start, sideToQueue.End);
var bbox2 = new Rectangle(sideWithRange.Start, sideWithRange.End);
if ((ScanDirection.IsHorizontal) ? !bbox1.IntersectsOnX(bbox2) : !bbox1.IntersectsOnY(bbox2)) {
return;
}
// Make sure we order the endpoints from low to high along the scanline parallel, and get only
// the intersection. RectilinearFileTests.Nudger_Overlap* exercise reflection lookahead subranges.
Rectangle bboxIntersect = Rectangle.Intersect(bbox1, bbox2);
Point low = bboxIntersect.LeftBottom;
Point high = bboxIntersect.RightTop;
// This is inclusive of the endpoints of sideWithRange, to be sure that we remove the item
// from LookaheadScan; if it's on an extreme vertex in the perpendicular sweep then it will
// stop the chain; see TestRectilinear.Reflection_Staircase_Stops_At_BoundingBox_Side*.
RBNode<BasicReflectionEvent> lookaheadSiteNode = lookaheadScan.FindFirstInRange(low, high);
while (null != lookaheadSiteNode) {
// Calculate the lookahead intersection with this side in the perpendicular direction to
// the scanline. Note: due to rounding error, this may be different from the calculation
// in the parallel direction when the scanline gets up to the ScanDirection.PerpCoord(intersect);
// this will be adjusted in ScanSegmentTree.MergeSegments.
Point intersect = ScanLineIntersectSide(lookaheadSiteNode.Item.Site, sideToQueue
, ScanDirection.PerpendicularInstance);
DevTraceInfoVgGen(1, "Loading reflection from lookahead site {0} to intersect at {1}"
, lookaheadSiteNode.Item.Site, intersect);
DevTraceInfoVgGen(2, " side {0})", sideToQueue); // same indent as AddSegment
// In some cases where the ActiveLowSide and ActiveHighSide of an obstacle lean in the same
// direction such that LowSide is above HighSide, e.g. on the horizontal pass when they both
// lean to the right, the delayed-lookahead in CloseVertex (obstacle close) event may find the
// high side spanning the scanline-parallel coordinate range where its low side has enqueued
// lookahead events. In that case the intersection will be less than the enqueueing site so
// ignore it. See RectilinearTests.ReflectionsSitedByLowSideAreNotLoadedByHighSide.)
// Similarly, if this is at the same perpendicular coordinate as the current scanline
// position, ignore it; otherwise we could back up in the scanline's parallel coordinate.
// Since we retrieved events for the endpoint of any previous side, this won't be
// encountered on a bend vertex event; therefore we're on a near-flat bottom side
// so we're parallel to the extreme-vertex line and it's fine to just absorb the photon.
// This also handles the case of reflections into intersecting sides - at some point
// they converge such that the intersection is not ahead of the lookahead site.
if (ScanDirection.ComparePerpCoord(intersect, lookaheadSiteNode.Item.Site) > 0) {
// Add an event to continue the chain, "shifting" the site's reflecting
// obstacle back to the initialObstacle position. We must load this here
// and process it in ConfirmLookaheadEvent so it will be removed from
// the lookahead list; we can't remove it here if it doesn't satisfy the
// staircase requirements, because this may be called from loading a "higher"
// side (during the sweep) which could steal events from the lower side.
AddReflectionEvent(lookaheadSiteNode.Item, sideToQueue, intersect);
}
else {
if (lookaheadSiteNode.Item.ReflectingObstacle != sideToQueue.Obstacle) {
DevTraceInfoVgGen(1, " (discarding reflection at intersect {0} as it is not ahead of the previous site)", intersect);
// We need to remove the site. We're in the middle of Node enumeration so just
// mark the site and on function exit we'll remove any so marked.
lookaheadScan.MarkStaleSite(lookaheadSiteNode.Item);
}
else {
DevTraceInfoVgGen(1, " (skipping reflection at intersect {0} as it is the same obstacle)", intersect);
}
}
// Get the next item, leaving the current one in the lookahead scan until
// we actually process the event; this lets us know whether an intervening
// obstacle may be opened and intercepted the reflection. ConfirmLookaheadEvents
// will actually do the removal when the lowest side containing the lookahead
// site is loaded. See RectilinearTests.ReflectionsRemoveInterceptedSite.
lookaheadSiteNode = lookaheadScan.FindNextInRange(lookaheadSiteNode, high);
} // endwhile previousSiteNode
lookaheadScan.RemoveStaleSites();
}
public double GetDistance(Rectangle rect1, Rectangle rect2) {
if (!Rectangle.Intersect(rect1, rect2).IsEmpty) return 0;
Rectangle leftmost = rect1.Left <= rect2.Left ? rect1 : rect2;
Rectangle notLeftmost = rect1.Left <= rect2.Left ? rect2 : rect1;
Rectangle botommost = rect1.Bottom <= rect2.Bottom ? rect1 : rect2;
Rectangle notBotommost = rect1.Bottom <= rect2.Bottom ? rect2 : rect1;
double dx = notLeftmost.Left - leftmost.Right;
double dy = notBotommost.Bottom - botommost.Top;
if(rect1.IntersectsOnX(rect2)) return dy;
if (rect1.IntersectsOnY(rect2)) return dx;
return Math.Sqrt(dx * dx + dy * dy);
}