private void WriteNurbsCurve(NurbsCurve nurbsCurve)
{
if (this.activeSection != StringCode.EntitiesSection && !this.isBlockEntities)
{
throw new InvalidDxfSectionException(this.activeSection, this.file);
}
//we will draw the nurbsCurve as a polyline, it is not supported in AutoCad12 dxf files
this.WriteCodePair(0, DxfObjectCode.Polyline);
this.WriteEntityCommonCodes(nurbsCurve);
//open polyline
this.WriteCodePair(70, 0);
//dummy point
this.WriteCodePair(10, 0.0);
this.WriteCodePair(20, 0.0);
this.WriteCodePair(30, nurbsCurve.Elevation);
this.WriteCodePair(39, nurbsCurve.Thickness);
this.WriteCodePair(210, nurbsCurve.Normal.X);
this.WriteCodePair(220, nurbsCurve.Normal.Y);
this.WriteCodePair(230, nurbsCurve.Normal.Z);
//Obsolete; formerly an “entities follow flag” (optional; ignore if present)
//but its needed to load the dxf file in AutoCAD
this.WriteCodePair(66, "1");
this.WriteXData(nurbsCurve.XData);
List<Vector2d> points = nurbsCurve.PolygonalVertexes(nurbsCurve.CurvePoints);
foreach (Vector2d v in points)
{
this.WriteCodePair(0, DxfObjectCode.Vertex);
this.WriteCodePair(8, nurbsCurve.Layer);
this.WriteCodePair(70, 0);
this.WriteCodePair(10, v.X);
this.WriteCodePair(20, v.Y);
}
this.WriteCodePair(0, StringCode.EndSequence);
}
private static void NurbsCurve()
{
DxfDocument dxf = new DxfDocument();
NurbsCurve nurbs = new NurbsCurve();
nurbs.ControlPoints .Add(new NurbsVertex( 0, 0));
nurbs.ControlPoints.Add(new NurbsVertex(10, 10));
nurbs.ControlPoints.Add(new NurbsVertex(20, 0));
nurbs.ControlPoints.Add(new NurbsVertex(30, 10));
nurbs.ControlPoints.Add(new NurbsVertex(40, 0));
nurbs.ControlPoints.Add(new NurbsVertex(50, 10));
nurbs.ControlPoints.Add(new NurbsVertex(60, 0));
nurbs.ControlPoints.Add(new NurbsVertex(70, 10));
nurbs.Order = 3;
dxf.AddEntity(nurbs);
NurbsCurve nurbs2 = new NurbsCurve();
nurbs2.ControlPoints.Add(new NurbsVertex(5, 0));
nurbs2.ControlPoints.Add(new NurbsVertex(10, 0));
nurbs2.ControlPoints.Add(new NurbsVertex(10, 5));
nurbs2.ControlPoints.Add(new NurbsVertex(10, 10));
nurbs2.ControlPoints.Add(new NurbsVertex(5, 10));
nurbs2.ControlPoints.Add(new NurbsVertex(0, 10));
nurbs2.ControlPoints.Add(new NurbsVertex(0, 5));
nurbs2.ControlPoints.Add(new NurbsVertex(0, 0));
nurbs2.ControlPoints.Add(new NurbsVertex(5, 0));
nurbs2.Order = 3;
nurbs2.SetUniformWeights((float)Math.Cos(MathHelper.HalfPI));
dxf.AddEntity(nurbs2);
dxf.Save("nurbs.dxf", DxfVersion.AutoCad12);
}