Create Polyline from Figure using .BaseCurve method

[stacy.dunn]

Partha,

in reference to your post http://adndevblog.typepad.com/infrastructure/2012/10/getting-civil-3d-land-featureline-vertices.html

You said that there is no need to flatten, but each method I have tried does not produce a polyline with curves.

I tried:

survfig.BaseCurve

survfig.BaseCurve.GetProjectedCurve

survig.BaseCurve.GetOrthoprojectedCurve

If if manually flatten the figure using a dummy suface with the AeccFeatureElevsFromSurf command, the polyline derived from survfig.BaseCurve will then have actual arc segments.

Is there another method or a way to flatten the figure programatically first?

Thank you,

Stacy

[Partha.Sarkar]

Hi Stacy,

Is it possible for you to upload a small data set to investigate the issue ?

Thanks,

Partha

[stacy.dunn]

Partha,

The attached drawing contains regular figures and one that I have manually flattened to a surface plane at zero elevation.  The regular figures will end up with line segments that represent the arcs, while the flattened figure will have actual arcs.

Thank you,

Stacy

[Jeff_M · Accepted solution]

Stacy, rather than flattening the figure or featureline I created some extension methods to recreate the polyline based on the actual segments from those objects. I offer them here for anyone to use. Yes, they are written in c# but should be easily portable to VB.NET.

/// 
/// Created by Jeff Mishler
/// Copyright © 2007-2012 Quux Software LLC
/// http://www.quuxsoft.com
/// All rights reserved.
/// 

using System.Collections.Generic;
using Autodesk.AutoCAD.DatabaseServices;
using Autodesk.AutoCAD.Geometry;
using Autodesk.Civil.ApplicationServices;
using Autodesk.Civil.DatabaseServices;

namespace Quux.C3DUtilities.Extensions
{
    /// <summary>
    /// These are mainly for use in C3D2012+, as the Featureline & Surface objects were not exposed to .NET until then.
    /// </summary>
    public static class FeaturelineExtensions
    {
        /// <summary>
        /// Method to get the 2D Polyline represented by the featureline
        /// </summary>
        /// <param name="fl"></param>
        /// <returns></returns>
        public static Polyline BaseCurve2d(this FeatureLine fl)
        {
            Polyline poly = fl.BaseCurve as Polyline;
            if (poly != null)
                return poly;
            object line = fl.AcadObject;
            poly = new Polyline();
            object[] args = new object[1];
            args[0] = 1;
            double[] vertices = (double[])line.GetType().InvokeMember("GetPoints", System.Reflection.BindingFlags.InvokeMethod, null, line, args);

            for (int i = 0, j = 0; i < vertices.Length; i = i + 3, j++)
            {
                Point2d pt = new Point2d(vertices[i], vertices[i + 1]);
                Point3d pt3d = new Point3d(vertices[i], vertices[i + 1], vertices[i + 2]);
                args[0] = pt3d.ToArray();
                double bulge = (double)line.GetType().InvokeMember("GetBulgeAtPoint", System.Reflection.BindingFlags.InvokeMethod, null, line, args);
                poly.AddVertexAt(j, pt, bulge, 0, 0);
            }

            return poly;
        }
    }
}

/// 
/// Created by Jeff Mishler
/// Copyright © 2012 Quux Software LLC
/// http://www.quuxsoft.com
/// 

using Autodesk.AutoCAD.DatabaseServices;
using Autodesk.Civil.DatabaseServices;

namespace Quux.C3DUtilities.Extensions
{
    public static class SurveyFigureExtensions
    {
        /// <summary>
        /// Method to get the 2D Polyline represented by the SurveyFigure
        /// </summary>
        /// <returns></returns>
        public static Polyline BaseCurve2d(this SurveyFigure fig)
        {
            Polyline poly = fig.BaseCurve as Polyline;
            if (poly != null)
                return poly;
            // A surveyfigure derives from a featureline so use it's extension method for the BaseCurve2d
            FeatureLine fl = fig as FeatureLine;
            poly = fl.BaseCurve2d();
            return poly;
        }
    }
}

[Partha.Sarkar]

Hi Stacy,

I tested my code snippet ( from the same blog post ) on your sample DWG file and I see they are perfectly converted to a polyline, of course, in this case they are converted to a 3D polyline as there are valid elevations attached to Survey Figure objects.

I have attached the screenshot from my investigation on your DWG file.

Cheers,

Partha

[Partha.Sarkar]

And if you want to remove the elevations from the 3dpolyline just run this command -

FLATTEN
Select objects to convert to 2d...

Cheers,

Partha

[stacy.dunn]

As always, thank you Jeff!

[stacy.dunn]

Partha,

My issue is not really with generating the polyline, it is with generating the polyline with true arc segments instead of short lines that represent an arc.

Thank you,

Stacy

[joantopo]

"Is there another method or a way to flatten the figure programatically first?"

You can previously select entities in drawing and then use a command method "RaiseLowerFeatures\nE " and value=0 to flatten.