private static Autodesk.Revit.DB.Curve Convert(Autodesk.DesignScript.Geometry.NurbsCurve crv)
{
// line
if (crv.Degree == 1 && crv.ControlPoints().Length == 2 && !crv.IsRational)
{
return Autodesk.Revit.DB.Line.CreateBound(crv.ControlPoints()[0].ToXyz(false),
crv.ControlPoints()[1].ToXyz(false));
}
// polyline - not allowed
if (crv.Degree == 1)
{
throw new Exception(
"Degree 1 Nurbs Curves are not allowed in Revit! Try splitting the curve into "
+
"individual linear pieces");
}
// bezier
if (crv.Degree == 2 && crv.ControlPoints().Count() == 3 && !crv.IsRational)
{
var converted = NurbsUtils.ElevateBezierDegree(crv, 3);
return Autodesk.Revit.DB.NurbSpline.Create(converted.ControlPoints().ToXyzs(false),
converted.Weights(),
converted.Knots(),
converted.Degree,
converted.IsClosed,
converted.IsRational);
}
// degree 2 curve
if (crv.Degree == 2)
{
// TODO: general NURBS degree elevation
var numSamples = crv.ControlPoints().Count() + 1;
var pts = Enumerable.Range(0, numSamples).Select(x => x/(double)numSamples)
.Select(crv.PointAtParameter);
var resampledCrv = NurbsCurve.ByPointsTangents(
pts,
crv.TangentAtParameter(0).Normalized(),
crv.TangentAtParameter(1).Normalized());
return Autodesk.Revit.DB.NurbSpline.Create(resampledCrv.ControlPoints().ToXyzs(false),
resampledCrv.Weights(),
resampledCrv.Knots(),
resampledCrv.Degree,
resampledCrv.IsClosed,
resampledCrv.IsRational);
}
// general implementation
return Autodesk.Revit.DB.NurbSpline.Create(crv.ControlPoints().ToXyzs(false),
crv.Weights(),
crv.Knots(),
crv.Degree,
crv.IsClosed,
crv.IsRational);
}