public static NurbsCurve ToRhino(DB.HermiteSpline hermite)
{
var nurbsCurve = ToRhino(DB.NurbSpline.Create(hermite));
nurbsCurve.Domain = new Interval(hermite.GetEndParameter(0), hermite.GetEndParameter(1));
return(nurbsCurve);
}
private static Autodesk.DesignScript.Geometry.Curve Convert(Autodesk.Revit.DB.HermiteSpline crv)
{
var convert = HermiteToNurbs.ConvertExact(crv);
if (!crv.IsBound)
{
return(convert);
}
// bound the curve parametric range
// we first get the full parametric domain from the parameters
// note that some knots be negative and the domain may appear reversed
var parms = crv.Parameters.Cast <double>().ToList();
var fsp = parms.First();
var fep = parms.Last();
// obtain the full domain
var fd = Math.Abs(fsp - fep);
// these are the start and end parameters of the bound curve
var sp = crv.get_EndParameter(0);
var ep = crv.get_EndParameter(1);
// get the normalized parameters for trim
var nsp = Math.Abs(fsp - sp) / fd;
var nep = Math.Abs(fsp - ep) / fd;
return(convert.ParameterTrim(nsp, nep));
}
private static bool IsLineLikeInternal(Autodesk.Revit.DB.HermiteSpline crv)
{
var controlPoints = crv.ControlPoints;
var controlPointsAligned = IsLineLikeInternal(controlPoints);
if (!controlPointsAligned)
{
return(false);
}
// It's possible for the control points to be straight, but the tangents
// might not be aligned with the curve. Let's check the tangents are aligned.
var line = Autodesk.DesignScript.Geometry.Line.ByStartPointEndPoint(
controlPoints.First().ToPoint(false),
controlPoints.Last().ToPoint(false));
var lineDir = line.Direction.Normalized().ToXyz(false);
var tangents = crv.Tangents;
var startTan = tangents.First().Normalize();
var endTan = tangents.Last().Normalize();
return(Math.Abs(startTan.DotProduct(endTan) - 1) < Tolerance &&
Math.Abs(lineDir.DotProduct(endTan) - 1) < Tolerance);
}
public override FScheme.Value Evaluate(FSharpList <FScheme.Value> args)
{
var pts = ((FScheme.Value.List)args[0]).Item;
hs = null;
var containers = Utils.SequenceToFSharpList(pts);
var ctrlPts = new List <XYZ>();
foreach (FScheme.Value e in containers)
{
if (e.IsContainer)
{
XYZ pt = (XYZ)((FScheme.Value.Container)(e)).Item;
ctrlPts.Add(pt);
}
}
if (pts.Count() > 0)
{
hs = dynRevitSettings.Doc.Application.Application.Create.NewHermiteSpline(ctrlPts, false);
}
return(FScheme.Value.NewContainer(hs));
}
/// <summary>
/// Convert a Revit HermiteSpline exactly to a NurbsCurve equivalent
/// </summary>
/// <param name="crv"></param>
/// <returns></returns>
public static NurbsCurve ConvertExact(Autodesk.Revit.DB.HermiteSpline crv)
{
var knots = Clamp(crv.Parameters.Cast <double>());
var points = GetNurbsPoints(crv, knots);
// the resultant nurbs curve is not rational - i.e. it's weights are 1
var weights = Enumerable.Repeat(1.0, points.Length).ToArray();
return(NurbsCurve.ByControlPointsWeightsKnots(points, weights, knots, 3));
}
public override FScheme.Value Evaluate(FSharpList<FScheme.Value> args)
{
var pts = ((FScheme.Value.List)args[0]).Item;
hs = null;
var containers = Utils.SequenceToFSharpList(pts);
var ctrlPts = new List<XYZ>();
foreach (FScheme.Value e in containers)
{
if (e.IsContainer)
{
XYZ pt = (XYZ)((FScheme.Value.Container)(e)).Item;
ctrlPts.Add(pt);
}
}
if (pts.Count() > 0)
{
hs = dynRevitSettings.Doc.Application.Application.Create.NewHermiteSpline(ctrlPts, false);
}
return FScheme.Value.NewContainer(hs);
}
public static Curve ToCurve(this DB.HermiteSpline value)
{
var rhino = RawDecoder.ToRhino(value); UnitConverter.Scale(rhino, UnitConverter.ToRhinoUnits); return(rhino);
}
/// <summary>
/// Obtain the Nurbs control points from a Hermite Spline
/// </summary>
/// <param name="curve"></param>
/// <param name="nurbsKnots"></param>
/// <returns></returns>
internal static Autodesk.DesignScript.Geometry.Point[] GetNurbsPoints(Autodesk.Revit.DB.HermiteSpline curve, double[] nurbsKnots)
{
int numKnots = nurbsKnots.Length;
int numPoints = numKnots - _cubicOrder;
var pPoints = new XYZ[numPoints];
for (int ii = 0; ii < numPoints; ii++)
{
double t = 0.5 * (nurbsKnots[ii] + nurbsKnots[ii + 1]);
var del = new double[_cubicOrder];
for (int jj = 1; jj <= _cubicDegree; jj++)
{
del[jj] = nurbsKnots[ii + jj] - t;
}
var s = Symmetric(del);
var psi = new double[_cubicOrder];
for (int k = 0; k <= _cubicDegree; k++)
{
double top = _power1[k] * _factorial[k] * s[_cubicDegree - k];
psi[k] = top / _factorial[_cubicDegree];
}
pPoints[ii] = XYZ.Zero;
var derivTransform = curve.ComputeDerivatives(t, false);
// this is the expected rep
var derivs = new[]
{
derivTransform.Origin,
derivTransform.BasisX, // 1st deriv
derivTransform.BasisY, // 2nd deriv
null
};
// calculate 3-th derivative
int low = 0;
int high = numPoints + 1;
int mid = (low + high) / 2;
while (t < nurbsKnots[mid] || t >= nurbsKnots[mid + 1])
{
if (t < nurbsKnots[mid])
{
high = mid;
}
else
{
low = mid;
}
mid = (low + high) / 2;
}
// find the span containing t
double p1 = nurbsKnots[mid];
double p2 = nurbsKnots[mid + 1];
// evaluate the point and tangent at the two end points of the span
var P1R1 = curve.ComputeDerivatives(p1, false);
var P1 = P1R1.Origin;
var R1 = P1R1.BasisX;
var P4R4 = curve.ComputeDerivatives(p2, false);
var P4 = P4R4.Origin;
var R4 = P4R4.BasisX;
// the chord vector from p1 to p2
var P14 = P1 - P4;
var R14 = R1 + R4;
// the span of the region is tk
double tk = p2 - p1;
if (tk < 1e-13)
{
tk = 1.0;
}
// an approximation of the third derivative
derivs[3] = P14 * (12.0 / (tk * tk * tk)) + R14 * (6.0 / (tk * tk));
for (int r = 0; r <= _cubicDegree; r++)
{
int codegree = _cubicDegree - r;
double mul = _power1[codegree] * psi[codegree];
pPoints[ii] = pPoints[ii] + mul * derivs[r];
}
}
return(pPoints.Select(x => x.ToPoint()).ToArray());
}
public static NurbsCurve ToRhino(this DB.HermiteSpline hermite) => RawDecoder.ToRhino(hermite);
