public Pnt3D GetNonIntersectingTargetPoint(
[NotNull] Linestring targetRing,
double distanceFromIntersectionAsRatio)
{
if (Type == IntersectionPointType.LinearIntersectionIntermediate ||
Type == IntersectionPointType.Unknown)
{
throw new InvalidOperationException(
$"Cannot get the non-intersecting target point for an intersection point type {Type}");
}
bool?deviationIsBackward = null;
if (Type == IntersectionPointType.LinearIntersectionStart ||
Type == IntersectionPointType.LinearIntersectionEnd)
{
// the direction matters:
deviationIsBackward =
Type == IntersectionPointType.LinearIntersectionStart;
if (SegmentIntersection.LinearIntersectionInOppositeDirection)
{
deviationIsBackward = !deviationIsBackward;
}
}
double targetFactor;
int targetSegmentIdx =
GetLocalTargetIntersectionSegmentIdx(targetRing, out targetFactor);
double adjustedTargetFactor;
if (deviationIsBackward == true)
{
adjustedTargetFactor = targetFactor - distanceFromIntersectionAsRatio;
}
else
{
// forward or null (i.e. does not matter)
adjustedTargetFactor = targetFactor + distanceFromIntersectionAsRatio;
if (adjustedTargetFactor > 1)
{
int?nextIdx = targetRing.NextSegmentIndex(targetSegmentIdx);
if (nextIdx != null)
{
targetSegmentIdx = nextIdx.Value;
adjustedTargetFactor -= 1;
}
else if (deviationIsBackward == null)
{
// cannot go forward, try backward:
adjustedTargetFactor =
targetFactor - distanceFromIntersectionAsRatio;
}
}
}
if (adjustedTargetFactor < 0)
{
int?previousIdx = targetRing.PreviousSegmentIndex(targetSegmentIdx);
if (previousIdx == null)
{
return(null);
}
targetSegmentIdx = previousIdx.Value;
adjustedTargetFactor += 1;
}
return(targetRing[targetSegmentIdx].GetPointAlong(adjustedTargetFactor, true));
}
/// <summary>
/// Gets the line that enters the intersection point when moving along as specified
/// with the direction parameters alongSource and forward.
/// </summary>
/// <param name="intoIntersection"></param>
/// <param name="target"></param>
/// <param name="alongSource"></param>
/// <param name="forward"></param>
/// <param name="source"></param>
/// <returns></returns>
protected static Line3D GetEntryLine([NotNull] IntersectionPoint3D intoIntersection,
[NotNull] Linestring source,
[NotNull] Linestring target,
bool alongSource, bool forward)
{
Line3D entryLine;
if (alongSource)
{
double distanceAlongSource;
int sourceSegmentIdx =
intoIntersection.GetLocalSourceIntersectionSegmentIdx(
source, out distanceAlongSource);
entryLine = distanceAlongSource > 0
? source[sourceSegmentIdx]
: source.PreviousSegmentInRing(sourceSegmentIdx);
}
else
{
double distanceAlongTarget;
int targetSegmentIdx = intoIntersection.GetLocalTargetIntersectionSegmentIdx(
target, out distanceAlongTarget);
if (forward)
{
if (distanceAlongTarget > 0)
{
entryLine = target[targetSegmentIdx];
}
else
{
// There must be a previous segment if we have come along the target
int previousTargetIdx =
Assert.NotNull(target.PreviousSegmentIndex(targetSegmentIdx)).Value;
entryLine = target[previousTargetIdx];
}
}
else
{
if (distanceAlongTarget < 1)
{
entryLine = target[targetSegmentIdx];
}
else
{
// There must be a next segment if we have come backwards along the target
int nextTargetIdx =
Assert.NotNull(target.NextSegmentIndex(targetSegmentIdx)).Value;
entryLine = target[nextTargetIdx];
}
entryLine = entryLine.Clone();
entryLine.ReverseOrientation();
}
}
return(entryLine);
}