Draw triangle in segment of polyline in segment direction

[pva75]

I want to draw triangle in segment of polyline in segment direction.

I have target segment and center point of it:

  Polyline line = ...
  LineSegment3d centerSegment = line.GetLineSegmentAt(centerSegmentIndex);
  Point3d centerPosition = centerSegment.MidPoint;

I can find direction of this segment:

  Vector3d zaDirection = line.GetLineSegmentAt(centerSegmentIndex).Direction;

Next, I create list of points:

  List<Point3d> points = new List<Point3d>();
  points.Add(centerPosition);
  points.Add(centerPosition.Add(new Vector3d(ZASize, +ZASize, 0)));
  points.Add(centerPosition.Add(new Vector3d(ZASize, -ZASize, 0)));

And draw it:

  wd.Geometry.Polygon(new Point3dCollection(points.ToArray()));

Ok, I have triangle but... it's not in segment direction, it's X-direction.

I try to rotate it:

  points.Add(centerPosition.Add(new Vector3d(ZASize, +ZASize, 0)).RotateBy(0, zaDirection, centerPosition));

But it's not the same as I want.

How I can draw triangle by serment direction?

Pavel.

[Hallex]

Pavel,

Upload a screenshot or image to see

what is your goal

~'J'~

[pva75]

Thanks,

Pavel.

[Hallex]

Well, I just finished to write an example, but it's not you exactly need

Try to rewrite you code using this example:

       public static Point3d PolarPoint(Point3d basepoint, double angle, double distance)
        {
            // credits to Tony Tanzillo
            return new Point3d(
            basepoint.X + (distance * Math.Cos(angle)),
            basepoint.Y + (distance * Math.Sin(angle)),
            basepoint.Z);
        }
        // by gile (Gilles Chanteau)
        // Clockwise method, returns 1 if p1, p2, p3 are clockwise,
        // 0 if they're aligned, -1 if they're counterclockwise

        public static int Clockwise(Point3d p1, Point3d p2, Point3d
        p3, Vector3d normal)
        {
            const double pi = 3.141592653589793;
            Vector3d v1 = p1.GetVectorTo(p2);
            Vector3d v2 = p1.GetVectorTo(p3);
            double angle = v1.GetAngleTo(v2, normal);
            if (angle == 0.0 || angle == pi)
                return 0;
            else
            {
                if (v1.GetAngleTo(v2, normal) < pi)
                    return -1;
                else
                    return 1;
            }
        }
        [CommandMethod("trio")]
        public static void DrawTriangles()
        {
            Document doc = Autodesk.AutoCAD.ApplicationServices.Application.DocumentManager.MdiActiveDocument;

            Database db = doc.Database;

            Editor ed = doc.Editor;

            bool success = false;
            double ZASize = 10.0;
            try
            {
                using (Transaction tr = db.TransactionManager.StartTransaction())
                {
                    ObjectId id = ed.GetEntity("\nSelect Polyline: ").ObjectId;
                    Entity ent = (Entity)tr.GetObject(id, OpenMode.ForRead);
                    Autodesk.AutoCAD.DatabaseServices.Polyline pline = ent as Autodesk.AutoCAD.DatabaseServices.Polyline;
                    Plane plan = new Plane(Point3d.Origin, pline.Normal);
                    BlockTableRecord btr = (BlockTableRecord)tr.GetObject(db.CurrentSpaceId, OpenMode.ForWrite);
                    
                    Point3d p1 = new Point3d(); Point3d p2 = new Point3d(); Point3d p3 = new Point3d(); int dir = 0;
                    if (pline.NumberOfVertices>2)
                    {
                         p1 = pline.GetPoint3dAt(0);
                         p2 = pline.GetPoint3dAt(1);
                         p3 = pline.GetPoint3dAt(2);
                    }

                    dir= Clockwise(p1,p2,p3,pline.Normal);
                   
                    for (int i = 0; i < pline.NumberOfVertices; i++)
                    {
                        Point3d ep=new Point3d();
                        if ((!pline.Closed) && ((i + 1) < pline.NumberOfVertices))
                        {
                            ep = pline.GetPoint3dAt(i + 1);
                            
                        }
                        else if (pline.Closed)
                        {
                            try
                            {
                                ep = pline.GetPoint3dAt(i + 1);
                            }
                            catch
                            {
                                ep = pline.GetPoint3dAt(0);
                            }
                        }
                        else
                        {
                            break;
                        }
                        Point3d sp = pline.GetPoint3dAt(i);
                        Point3d centerPosition = new Point3d((sp.X + ep.X) / 2, (sp.Y + ep.Y) / 2, (sp.Z + ep.Z) / 2);
                        //I can find direction of this segment:
                        double perp;
                        if (dir > 0)
                        {
                             perp = (ep - sp).GetPerpendicularVector().AngleOnPlane(plan);
                        }
                        else
                        {
                             perp = (sp - ep).GetPerpendicularVector().AngleOnPlane(plan);
                        }
                        Point3d ap = PolarPoint(centerPosition, perp, ZASize);

                        //Next, I create list of points:

                        List<Point3d> points = new List<Point3d>();
                        points.Add(sp);
                        
                        points.Add(ap);
                        points.Add(ep);
                        Autodesk.AutoCAD.DatabaseServices.Polyline tri = new Autodesk.AutoCAD.DatabaseServices.Polyline();
                        for (int n = 0; n < points.Count; n++)
                        {
                            tri.AddVertexAt(n, new Point2d(points[n].X, points[n].Y), 0, 0, 0);
                        }
                        // commented overruling code block, I did't test this part of code
                       // wd.Geometry.Polygon(new Point3dCollection(points.ToArray()));
                        btr.AppendEntity(tri); tr.AddNewlyCreatedDBObject(tri, true);
                    }
                    success = true;
                    tr.Commit();
                }

            }

            catch (Autodesk.AutoCAD.Runtime.Exception ex)
            {
                Application.DocumentManager.MdiActiveDocument.Editor.WriteMessage(ex.Message + "\n" + ex.StackTrace);
                success = false;
            }
            finally
            {
                if (success==false)
                Application.ShowAlertDialog(new ErrorStatus().ToString());
            }
        }

~'J'~

[pva75]

Thanks for idea with Plan class. I did it!

It's my code:

Plane plan = newPlane(Point3d.Origin, line.Normal);

double angle = zaDirection.AngleOnPlane(plan);

List<Point3d> points = newList<Point3d>();

points.Add(centerPosition.RotateBy(angle, line.Normal, centerPosition));

points.Add(centerPosition.Add(newVector3d(ZASize, +ZASize, 0)).RotateBy(angle, line.Normal, centerPosition));

points.Add(centerPosition.Add(newVector3d(ZASize, -ZASize, 0)).RotateBy(angle, line.Normal, centerPosition));

wd.Geometry.Polygon(new Point3dCollection(points.ToArray()));

Thanks,

Pavel.

[Hallex]

Glad you solved it

Cheers

~'J'~