Spline.md

Spline Class

Overview

The Spline class represents a smooth curve defined by control points and fit points in AutoCAD.

Namespace

Autodesk.AutoCAD.DatabaseServices

Inheritance Hierarchy

System.Object
  └─ RXObject
      └─ DBObject
          └─ Entity
              └─ Curve
                  └─ Spline

Key Properties

Property	Type	Description
Degree	int	Gets the degree of the spline
Rational	bool	Gets whether the spline is rational (NURBS)
Closed	bool	Gets/sets whether the spline is closed
Periodic	bool	Gets whether the spline is periodic
NumControlPoints	int	Gets the number of control points
NumFitPoints	int	Gets the number of fit points

Key Methods

Method	Return Type	Description
SetControlPointAt(int, Point3d)	void	Sets a control point
GetControlPointAt(int)	Point3d	Gets a control point
SetFitPointAt(int, Point3d)	void	Sets a fit point
GetFitPointAt(int)	Point3d	Gets a fit point

Code Examples

Example 1: Creating a Spline from Fit Points

using (Transaction tr = db.TransactionManager.StartTransaction())
{
    BlockTableRecord btr = tr.GetObject(db.CurrentSpaceId, OpenMode.ForWrite) as BlockTableRecord;
    
    Point3dCollection fitPoints = new Point3dCollection();
    fitPoints.Add(new Point3d(0, 0, 0));
    fitPoints.Add(new Point3d(50, 50, 0));
    fitPoints.Add(new Point3d(100, 25, 0));
    fitPoints.Add(new Point3d(150, 75, 0));
    fitPoints.Add(new Point3d(200, 50, 0));
    
    Spline spline = new Spline(fitPoints, 3, 0.0); // Degree 3, tolerance 0
    
    btr.AppendEntity(spline);
    tr.AddNewlyCreatedDBObject(spline, true);
    
    tr.Commit();
}

Related Objects

• Polyline - Multi-segment line
• Curve - Base class

References

• Autodesk Official Documentation