public static IEnumerable <TrackEvent> FollowTrack(RailTrack track, double startSpan, double distance)
{
const int MAX_ITERATIONS = 100;
double distanceFromStart = 0f;
for (int i = 0; i < MAX_ITERATIONS; i++)
{
yield return(new TrackChangeEvent(distanceFromStart, track.logicTrack.ID));
bool travelDirection = distance > 0;
var trackEvents = TrackIndexer
.GetTrackEvents(track, travelDirection, startSpan)
.Offset(distanceFromStart);
foreach (var trackEvent in trackEvents)
{
yield return(trackEvent);
}
double newSpan = startSpan + distance;
Junction nextJunction;
Junction.Branch nextBranch;
if (newSpan < 0)
{
nextBranch = track.GetInBranch();
if (nextBranch == null)
{
yield break;
}
distance += startSpan;
distanceFromStart += startSpan;
if (nextBranch.first)
{
distance *= -1;
}
nextJunction = track.inJunction;
}
else
{
double trackSpan = track.GetPointSet().span;
if (newSpan >= trackSpan)
{
nextBranch = track.GetOutBranch();
if (nextBranch == null)
{
yield break;
}
distance -= trackSpan - startSpan;
distanceFromStart += trackSpan - startSpan;
if (!nextBranch.first)
{
distance *= -1;
}
nextJunction = track.outJunction;
}
else
{
yield break;
}
}
if (nextBranch == null)
{
yield break;
}
if (nextJunction != null && nextJunction.inBranch.track == track)
{
yield return(new JunctionEvent(distanceFromStart, true, nextJunction));
}
track = nextBranch.track;
startSpan = nextBranch.first ? 0.0 : nextBranch.track.GetPointSet().span;
}
}