topic Re: find nearest lines(or pline) from selected point in .NET Forum

find nearest lines(or pline) from selected point

iPranavKulkarni — Mon, 12 Jun 2023 05:52:04 GMT

Hi, I tried to trace boundary from selected point (close boundary with polyline) but I need to find/get nearest lines.
can some one help me with this.

I tried:

Entity pl = tr.GetObject(per.ObjectId, OpenMode.ForRead) as Entity; //entity is polyline Extents3d extents = pl.GeometricExtents; Point3d center = extents.MinPoint + (extents.MaxPoint - extents.MinPoint) / 2.0;

Need to find lines from point in all direction

Re: find nearest lines(or pline) from selected point

_gile — Mon, 12 Jun 2023 10:59:49 GMT

Hi,

Here's a way to get the closest curve to a point.

public static Curve GetClosestCurve(IEnumerable<Curve> curves, Point3d pt) { var closest = curves.First(); var minDist = pt.DistanceTo(closest.GetClosestPointTo(pt, false)); foreach (var curve in curves.Skip(1)) { double dist = pt.DistanceTo(curve.GetClosestPointTo(pt, false)); if (dist < minDist) { minDist = dist; closest = curve; } } return closest; }

The same thing with F#:

let getClosestCurve (pt: Point3d) = Seq.minBy (fun (c: Curve) -> pt.DistanceTo(c.GetClosestPointTo(pt, false)))

Re: find nearest lines(or pline) from selected point

_gile — Mon, 12 Jun 2023 11:41:00 GMT

.NET 7 has a MinBy (and MaxBy) extension method but as we're limited to .NET Framework with AutoCAD, we need to build it (the following extension methods are taken from Gile.AutoCAD.Extension library).

public static class LinqExtension { /// <summary> /// Gets the smallest item of the sequence using the default comparer with the 'selector' function returned values. /// </summary> /// <typeparam name="TSource">Type the items.</typeparam> /// <typeparam name="TKey">Type of the returned value of 'selector' function.</typeparam> /// <param name="source">Sequence to which the method applies.</param> /// <param name="selector">Mapping function from 'TSource' to 'TKey'.</param> /// <returns>The smallest item in the sequence.</returns> /// <exception cref="System.ArgumentNullException">Thrown if 'source' is null.</exception> /// <exception cref="System.ArgumentNullException">Thrown if 'selector' is null.</exception> public static TSource MinBy<TSource, TKey>( this IEnumerable<TSource> source, Func<TSource, TKey> selector) { return source.MinBy(selector, Comparer<TKey>.Default); } /// <summary> /// Gets the smallest item of the sequence using the 'comparer' with the 'selector' function returned values. /// </summary> /// <typeparam name="TSource">Type the items.</typeparam> /// <typeparam name="TKey">Type of the returned value of 'selector' function.</typeparam> /// <param name="source">Sequence to which the method applies.</param> /// <param name="selector">Mapping function from 'TSource' to 'TKey'.</param> /// <param name="comparer">Comparer used for the type 'TKey'.</param> /// <returns>The smallest item in the sequence.</returns> /// <exception cref="System.ArgumentNullException">Thrown if 'source' is null.</exception> /// <exception cref="System.ArgumentNullException">Thrown if 'selector' is null.</exception> /// <exception cref="System.ArgumentNullException">Thrown if 'comparer' is null.</exception> public static TSource MinBy<TSource, TKey>( this IEnumerable<TSource> source, Func<TSource, TKey> selector, IComparer<TKey> comparer) { if (source == null) throw new ArgumentNullException(nameof(source)); if (selector == null) throw new ArgumentNullException(nameof(selector)); if (comparer == null) throw new ArgumentNullException(nameof(comparer)); using (var iterator = source.GetEnumerator()) { if (!iterator.MoveNext()) throw new InvalidOperationException("Empty sequence"); var min = iterator.Current; var minKey = selector(min); while (iterator.MoveNext()) { var current = iterator.Current; var currentKey = selector(current); if (comparer.Compare(currentKey, minKey) < 0) { min = current; minKey = currentKey; } } return min; } } }

Now the GetClosestCurve can be simply written:

public static Curve GetClosestCurve(IEnumerable<Curve> curves, Point3d pt) => curves.MinBy(c => pt.DistanceTo(c.GetClosestPointTo(pt, false)));

Re: find nearest lines(or pline) from selected point

iPranavKulkarni — Wed, 21 Jun 2023 11:22:54 GMT

Thanks!
Is this possible with the direction(axis)?

I need to get closest line in X-dir, Y-dir.(left right up and down)

Re: find nearest lines(or pline) from selected point

_gile — Wed, 21 Jun 2023 14:48:15 GMT

This should work (returns null if none curve found on the axis):

public static Curve GetClosestCurve(IEnumerable<Curve> curves, Point3d point, Vector3d axis) { using (var xline = new Xline { BasePoint = point, UnitDir = axis }) { var curvesOnAxis = new Dictionary<Curve, Point3d>(); Curve closestCurve = null; double minDist = double.MaxValue; foreach (var curve in curves) { var points = new Point3dCollection(); curve.IntersectWith(xline, Intersect.OnBothOperands, points, IntPtr.Zero, IntPtr.Zero); if (0 < points.Count) { double dist = points.Cast<Point3d>().Select(p => p.DistanceTo(point)).Min(); if (dist < minDist) { closestCurve = curve; minDist = dist; } } } return closestCurve; } }

Re: find nearest lines(or pline) from selected point

iPranavKulkarni — Thu, 22 Jun 2023 06:16:28 GMT

thanks for your support. It worked for me with small changes.

Re: find nearest lines(or pline) from selected point

iPranavKulkarni — Thu, 22 Jun 2023 06:39:56 GMT

thanks with your support I can get all the lines and closest line from that.
now I am finding some of lines in all direction.

need to get boundary (trace boundary)