using Autodesk.AutoCAD.ApplicationServices; using Autodesk.AutoCAD.DatabaseServices; using Autodesk.AutoCAD.EditorInput; using Autodesk.AutoCAD.Runtime; using Autodesk.AutoCAD.Geometry; using System.Collections.Generic; namespace MinimumEnclosingCircle { public class Commands { [CommandMethod("MEC", CommandFlags.UsePickSet)] public void MinimumEnclosingCircle() { Document doc = Application.DocumentManager.MdiActiveDocument; Database db = doc.Database; Editor ed = doc.Editor; // Ask user to select entities PromptSelectionOptions pso = new PromptSelectionOptions(); pso.MessageForAdding = "\nSelect objects to enclose: "; pso.AllowDuplicates = false; pso.AllowSubSelections = true; pso.RejectObjectsFromNonCurrentSpace = true; pso.RejectObjectsOnLockedLayers = false; PromptSelectionResult psr = ed.GetSelection(pso); if (psr.Status != PromptStatus.OK) return; bool oneCircPerEnt = false; if (psr.Value.Count > 1) { PromptKeywordOptions pko = new PromptKeywordOptions( "\nMultiple objects selected: create " + "individual circles around each one?" ); pko.AllowNone = true; pko.Keywords.Add("Yes"); pko.Keywords.Add("No"); pko.Keywords.Default = "No"; PromptResult pkr = ed.GetKeywords(pko); if (pkr.Status != PromptStatus.OK) return; oneCircPerEnt = (pkr.StringResult == "Yes"); } // There may be a SysVar defining the buffer // to add to our radius double buffer = 0.0; try { object bufvar = Application.GetSystemVariable( "ENCLOSINGCIRCLEBUFFER" ); if (bufvar != null) { short bufval = (short)bufvar; buffer = bufval / 100.0; } } catch { object bufvar = Application.GetSystemVariable("USERI1"); if (bufvar != null) { short bufval = (short)bufvar; buffer = bufval / 100.0; } } // Get the current UCS CoordinateSystem3d ucs = ed.CurrentUserCoordinateSystem.CoordinateSystem3d; // Collect points on the component entities Point3dCollection pts = new Point3dCollection(); Transaction tr = db.TransactionManager.StartTransaction(); using (tr) { BlockTableRecord btr = (BlockTableRecord)tr.GetObject( db.CurrentSpaceId, OpenMode.ForWrite ); for (int i = 0; i < psr.Value.Count; i++) { Entity ent = (Entity)tr.GetObject( psr.Value[i].ObjectId, OpenMode.ForRead ); // Collect the points for each selected entity Point3dCollection entPts = CollectPoints(tr, ent); foreach (Point3d pt in entPts) { /* * Create a DBPoint, for testing purposes * DBPoint dbp = new DBPoint(pt); btr.AppendEntity(dbp); tr.AddNewlyCreatedDBObject(dbp, true); */ pts.Add(pt); } // Create a circle for each entity (if so chosen) or // just once after collecting all the points if (oneCircPerEnt || i == psr.Value.Count - 1) { try { Circle cir = CircleFromPoints(pts, ucs, buffer); btr.AppendEntity(cir); tr.AddNewlyCreatedDBObject(cir, true); } catch { ed.WriteMessage( "\nUnable to calculate enclosing circle." ); } pts.Clear(); } } tr.Commit(); } } private Point3dCollection CollectPoints( Transaction tr, Entity ent ) { // The collection of points to populate and return Point3dCollection pts = new Point3dCollection(); // We'll start by checking a block reference for // attributes, getting their bounds and adding // them to the point list. We'll still explode // the BlockReference later, to gather points // from other geometry, it's just that approach // doesn't work for attributes (we only get the // AttributeDefinitions, which don't have bounds) BlockReference br = ent as BlockReference; if (br != null) { foreach (ObjectId arId in br.AttributeCollection) { DBObject obj = tr.GetObject(arId, OpenMode.ForRead); if (obj is AttributeReference) { AttributeReference ar = (AttributeReference)obj; ExtractBounds(ar, pts); } } } // If we have a curve - other than a polyline, which // we will want to explode - we'll get points along // its length Curve cur = ent as Curve; if (cur != null && !(cur is Polyline || cur is Polyline2d || cur is Polyline3d)) { // Two points are enough for a line, we'll go with // a higher number for other curves int segs = (ent is Line ? 2 : 20); double param = cur.EndParam - cur.StartParam; for (int i = 0; i < segs; i++) { try { Point3d pt = cur.GetPointAtParameter( cur.StartParam + (i * param / (segs - 1)) ); pts.Add(pt); } catch { } } } else if (ent is DBPoint) { // Points are easy pts.Add(((DBPoint)ent).Position); } else if (ent is DBText) { // For DBText we use the same approach as // for AttributeReferences ExtractBounds((DBText)ent, pts); } else if (ent is MText) { // MText is also easy - you get all four corners // returned by a function. That said, the points // are of the MText's box, so may well be different // from the bounds of the actual contents MText txt = (MText)ent; Point3dCollection pts2 = txt.GetBoundingPoints(); foreach (Point3d pt in pts2) { pts.Add(pt); } } else if (ent is Face) { Face f = (Face)ent; try { for (short i = 0; i < 4; i++) { pts.Add(f.GetVertexAt(i)); } } catch { } } else if (ent is Solid) { Solid sol = (Solid)ent; try { for (short i = 0; i < 4; i++) { pts.Add(sol.GetPointAt(i)); } } catch { } } else { // Here's where we attempt to explode other types // of object DBObjectCollection oc = new DBObjectCollection(); try { ent.Explode(oc); if (oc.Count > 0) { foreach (DBObject obj in oc) { Entity ent2 = obj as Entity; if (ent2 != null && ent2.Visible) { foreach (Point3d pt in CollectPoints(tr, ent2)) { pts.Add(pt); } } obj.Dispose(); } } } catch { } } return pts; } private void ExtractBounds( DBText txt, Point3dCollection pts ) { // We have a special approach for DBText and // AttributeReference objects, as we want to get // all four corners of the bounding box, even // when the text or the containing block reference // is rotated if (txt.Bounds.HasValue && txt.Visible) { // Create a straight version of the text object // and copy across all the relevant properties // (stopped copying AlignmentPoint, as it would // sometimes cause an eNotApplicable error) // We'll create the text at the WCS origin // with no rotation, so it's easier to use its // extents DBText txt2 = new DBText(); txt2.Normal = Vector3d.ZAxis; txt2.Position = Point3d.Origin; // Other properties are copied from the original txt2.TextString = txt.TextString; txt2.TextStyleId = txt.TextStyleId; txt2.LineWeight = txt.LineWeight; txt2.Thickness = txt2.Thickness; txt2.HorizontalMode = txt.HorizontalMode; txt2.VerticalMode = txt.VerticalMode; txt2.WidthFactor = txt.WidthFactor; txt2.Height = txt.Height; txt2.IsMirroredInX = txt2.IsMirroredInX; txt2.IsMirroredInY = txt2.IsMirroredInY; txt2.Oblique = txt.Oblique; // Get its bounds if it has them defined // (which it should, as the original did) if (txt2.Bounds.HasValue) { Point3d maxPt = txt2.Bounds.Value.MaxPoint; // Place all four corners of the bounding box // in an array Point2d[] bounds = new Point2d[] { Point2d.Origin, new Point2d(0.0, maxPt.Y), new Point2d(maxPt.X, maxPt.Y), new Point2d(maxPt.X, 0.0) }; // We're going to get each point's WCS coordinates // using the plane the text is on Plane pl = new Plane(txt.Position, txt.Normal); // Rotate each point and add its WCS location to the // collection foreach (Point2d pt in bounds) { pts.Add( pl.EvaluatePoint( pt.RotateBy(txt.Rotation, Point2d.Origin) ) ); } } } } private Circle CircleFromPoints( Point3dCollection pts, CoordinateSystem3d ucs, double buffer ) { // Get the plane of the UCS Plane pl = new Plane(ucs.Origin, ucs.Zaxis); // We will project these (possibly 3D) points onto // the plane of the current UCS, as that's where // we will create our circle // Project the points onto it List<Point2d> pts2d = new List<Point2d>(pts.Count); for (int i = 0; i < pts.Count; i++) { pts2d.Add(pl.ParameterOf(pts[i])); } // Assuming we have some points in our list... if (pts.Count > 0) { // We need the center and radius of our circle Point2d center; double radius = 0; // Use our fast approximation algorithm to // calculate the center and radius of our // circle to within 1% (calling the function // with 100 iterations gives 10%, calling it // with 10K gives 1%) BadoiuClarksonIteration( pts2d, 10000, out center, out radius ); // Get our center point in WCS (on the plane // of our UCS) Point3d cen3d = pl.EvaluatePoint(center); // Create the circle and add it to the drawing return new Circle( cen3d, ucs.Zaxis, radius * (1.0 + buffer) ); } return null; } // Algorithm courtesy (and copyright of) Frank Nielsen // http://blog.informationgeometry.org/article.php?id=164 public void BadoiuClarksonIteration( List<Point2d> set, int iter, out Point2d cen, out double rad ) { // Choose any point of the set as the initial // circumcenter cen = set[0]; rad = 0; for (int i = 0; i < iter; i++) { int winner = 0; double distmax = (cen - set[0]).Length; // Maximum distance point for (int j = 1; j < set.Count; j++) { double dist = (cen - set[j]).Length; if (dist > distmax) { winner = j; distmax = dist; } } rad = distmax; // Update cen = new Point2d( cen.X + (1.0 / (i + 1.0)) * (set[winner].X - cen.X), cen.Y + (1.0 / (i + 1.0)) * (set[winner].Y - cen.Y) ); } } } }