/// <summary>
///
/// </summary>
/// <param name="length"></param>
/// <returns></returns>
private LinearLocation GetLocationForward(double length)
{
if (length <= 0.0)
{
return(new LinearLocation());
}
double totalLength = 0.0;
var it = new LinearIterator(_linearGeom);
while (it.HasNext())
{
/**
* Special handling is required for the situation when the
* length references exactly to a component endpoint.
* In this case, the endpoint location of the current component
* is returned,
* rather than the startpoint location of the next component.
* This produces consistent behaviour with the project method.
*/
if (it.IsEndOfLine)
{
if (totalLength == length)
{
int compIndex = it.ComponentIndex;
int segIndex = it.VertexIndex;
return(new LinearLocation(compIndex, segIndex, 0.0));
}
}
else
{
var p0 = it.SegmentStart;
var p1 = it.SegmentEnd;
double segLen = p1.Distance(p0);
// length falls in this segment
if (totalLength + segLen > length)
{
double frac = (length - totalLength) / segLen;
int compIndex = it.ComponentIndex;
int segIndex = it.VertexIndex;
return(new LinearLocation(compIndex, segIndex, frac));
}
totalLength += segLen;
}
it.Next();
}
// length is longer than line - return end location
return(LinearLocation.GetEndLocation(_linearGeom));
}
/// <summary>
/// Find the nearest <see cref="LinearLocation" /> along the linear <see cref="Geometry" />
/// to a given <see cref="Geometry" /> after the specified minimum <see cref="LinearLocation" />.
/// If possible the location returned will be strictly greater than the <paramref name="minIndex" />.
/// If this is not possible, the value returned will equal <paramref name="minIndex" />.
/// (An example where this is not possible is when <paramref name="minIndex" /> = [end of line] ).
/// </summary>
/// <param name="inputPt">The coordinate to locate.</param>
/// <param name="minIndex">The minimum location for the point location.</param>
/// <returns>The location of the nearest point.</returns>
public LinearLocation IndexOfAfter(Coordinate inputPt, LinearLocation minIndex)
{
if (minIndex == null)
{
return(IndexOf(inputPt));
}
// sanity check for minLocation at or past end of line
var endLoc = LinearLocation.GetEndLocation(_linearGeom);
if (endLoc.CompareTo(minIndex) <= 0)
{
return(endLoc);
}
var closestAfter = IndexOfFromStart(inputPt, minIndex);
/*
* Return the minDistanceLocation found.
* This will not be null, since it was initialized to minLocation
*/
Assert.IsTrue(closestAfter.CompareTo(minIndex) >= 0, "computed location is before specified minimum location");
return(closestAfter);
}
