topic Re: Is there a way to return Points in a circle? in Civil 3D Customization Forum

Is there a way to return Points in a circle?

rampseeker — Mon, 23 Dec 2024 08:37:55 GMT

I want to select only the points within a certain circle among the points on a certain layer.

What I initially thought was to store all the x,y coordinates of the points and then loop through and inspect all the point data when a circle is selected.
However, this method seems to become more inefficient as there are more points.
If there is any other way, I would appreciate it if you could let me know.

Re: Is there a way to return Points in a circle?

Domzinator — Tue, 24 Dec 2024 16:29:34 GMT

Here is Some code that i use in one of my plugins. In this example i just highlight the points you can change it to suite your needs:

public static void SelectPointsInCircle() { Document doc = Application.DocumentManager.MdiActiveDocument; Editor ed = doc.Editor; Database db = doc.Database; try { // Prompt the user to select a circle PromptEntityOptions peo = new PromptEntityOptions("\nSelect a circle: "); peo.SetRejectMessage("\nThe selected object is not a circle."); peo.AddAllowedClass(typeof(Circle), false); PromptEntityResult per = ed.GetEntity(peo); if (per.Status != PromptStatus.OK) return; // Open the selected circle using (Transaction tr = db.TransactionManager.StartTransaction()) { Circle circle = tr.GetObject(per.ObjectId, OpenMode.ForRead) as Circle; if (circle == null) return; Point3d center = circle.Center; double radius = circle.Radius; // Create a selection filter for Civil 3D points TypedValue[] filterList = new TypedValue[] { new TypedValue((int)DxfCode.Start, "AECC_COGO_POINT") }; SelectionFilter filter = new SelectionFilter(filterList); // Select all points in the drawing PromptSelectionResult psr = ed.SelectAll(filter); if (psr.Status != PromptStatus.OK) { ed.WriteMessage("\nNo points found in the drawing."); return; } SelectionSet selSet = psr.Value; ObjectIdCollection selectedPoints = new ObjectIdCollection(); foreach (SelectedObject selObj in selSet) { if (selObj != null) { CogoPoint point = tr.GetObject(selObj.ObjectId, OpenMode.ForRead) as CogoPoint; if (point != null) { // Check if the point is within the circle if (center.DistanceTo(point.Location) <= radius) { selectedPoints.Add(point.ObjectId); } } } } // Highlight the selected points if (selectedPoints.Count > 0) { foreach (ObjectId id in selectedPoints) { Entity entity = tr.GetObject(id, OpenMode.ForWrite) as Entity; if (entity != null) { entity.Highlight(); } } ed.WriteMessage($"\n{selectedPoints.Count} points were selected within the circle."); } else { ed.WriteMessage("\nNo points were found in the circle."); } tr.Commit(); } } catch (System.Exception ex) { ed.WriteMessage($"\nError: {ex.Message}"); } }

Re: Is there a way to return Points in a circle?

essam-salah — Tue, 24 Dec 2024 18:04:21 GMT

hi @rampseeker

you can basically filter all points that lies inside a rectangle of P1/P2 by checking (or selecting) points with x,y > P1 and < P2 with simple math, then filter by the d <= r, where:
C = circle.CenterPoint
r = circle.Radius
P1.X = C.X - r
P1.Y = C.Y - r
P2.X = C.X + r
P2.Y = C.Y + r

d = distanceBetweeen(C, p)

note that the first filtering can be done by fence selection by 4 points of the rectangle of P1/P2

Re: Is there a way to return Points in a circle?

rampseeker — Wed, 25 Dec 2024 23:19:40 GMT

Thank you so much for your reply! I initially thought it would be simple to select entities that touch or are contained within the circle, but after several days of searching, I realized there isn't a function for that. I also came to understand that the method you suggested seems to be the best approach. I really appreciate your help.

Re: Is there a way to return Points in a circle?

rampseeker — Wed, 25 Dec 2024 23:24:59 GMT

Initially, I tried to filter the data using the method you suggested, but the issue was that all the points had to be loaded for the function to work. I was hoping there might be a way to simply check if any points existed among the entities within the circle. However, after searching for a few days, I realized that wasn't possible. Thank you so much for your reply.