///<summary>
/// Computes the <see cref="Coordinate"/> for the point on the line at the given index, offset by the given distance.
///</summary>
/// <remarks>
/// If the index is out of range the first or last point on the line will be returned.
/// The computed point is offset to the left of the line if the offset distance is
/// positive, to the right if negative.
/// The Z-ordinate of the computed point will be interpolated from the Z-ordinates of the line segment containing it, if they exist.
/// </remarks>
/// <param name="index">The index of the desired point</param>
/// <param name="offsetDistance">The distance the point is offset from the segment (positive is to the left, negative is to the right)</param>
/// <returns>The Coordinate at the given index</returns>
public Coordinate ExtractPoint(double index, double offsetDistance)
{
LinearLocation loc = LengthLocationMap.GetLocation(_linearGeom, index);
LinearLocation locLow = loc.ToLowest(_linearGeom);
return(locLow.GetSegment(_linearGeom).PointAlongOffset(locLow.SegmentFraction, offsetDistance));
}
/// <summary>
/// Computes the <see cref="Coordinate"/> for the point
/// on the line at the given index, offset by the given distance.
/// If the index is out of range the first or last point on the
/// line will be returned.<para/>
/// The computed point is offset to the left of the line if the offset distance is
/// positive, to the right if negative.<para/>
/// The Z-ordinate of the computed point will be interpolated from
/// the Z-ordinates of the line segment containing it, if they exist.
/// </summary>
/// <param name="index">The index of the desired point</param>
/// <param name="offsetDistance">The distance the point is offset from the segment
/// (positive is to the left, negative is to the right)</param>
/// <returns>The Coordinate at the given index</returns>
public Coordinate ExtractPoint(LinearLocation index, double offsetDistance)
{
var indexLow = index.ToLowest(_linearGeom);
return(indexLow.GetSegment(_linearGeom).PointAlongOffset(indexLow.SegmentFraction, offsetDistance));
}
