public IParametricCurve2d Clone()
{
NURBSCurve2 c2 = new NURBSCurve2();
c2.mNumCtrlPoints = this.mNumCtrlPoints;
c2.mCtrlPoint = (Vector2D[])this.mCtrlPoint.Clone();
c2.mCtrlWeight = (double[])this.mCtrlWeight.Clone();
c2.mLoop = this.mLoop;
c2.mBasis = this.mBasis.Clone();
c2.mReplicate = this.mReplicate;
c2.is_closed = this.is_closed;
return(c2);
}
// special case nurbs sampler. Computes a separate sampling of each unique knot interval
// of the curve parameter space. Reasoning:
// 1) computing Arc Length of an entire nurbs curve is quite slow if the curve has
// repeated knots. these become discontinuities which mean the numerical integrator
// has to do a lot of work. Instead we integrate between the discontinuities.
// 2) by sampling per-knot-interval, we ensure we always place a sample at each knot
// value. If we don't do this, we can "miss" the sharp corners at duplicate knots.
// 3) within each interval, we compute arc length and # of steps, but then sample
// by subdividing the T-interval. This is not precise arc-length sampling but
// is closer than uniform-T along the curve. And it means we don't have to
// do an arc-length evaluation for each point, which is very expensive!!
public static VectorArray2d SampleNURBSHybrid(NURBSCurve2 curve, double fSpacing)
{
List <double> intervals = curve.GetParamIntervals();
int N = intervals.Count - 1;
VectorArray2d[] spans = new VectorArray2d[N];
int nTotal = 0;
for (int i = 0; i < N; ++i)
{
double t0 = intervals[i];
double t1 = intervals[i + 1];
double fLen = curve.GetLength(t0, t1);
int nSteps = Math.Max((int)(fLen / fSpacing) + 1, 2);
double div = 1.0 / nSteps;
if (curve.IsClosed == false && i == N - 1)
{
nSteps++;
div = 1.0 / (nSteps - 1);
}
VectorArray2d vec = new VectorArray2d(nSteps);
for (int j = 0; j < nSteps; ++j)
{
double a = (double)j * div;
double t = (1 - a) * t0 + (a) * t1;
vec[j] = curve.SampleT(t);
}
spans[i] = vec;
nTotal += nSteps;
}
VectorArray2d final = new VectorArray2d(nTotal);
int iStart = 0;
for (int i = 0; i < N; ++i)
{
final.Set(iStart, spans[i].Count, spans[i]);
iStart += spans[i].Count;
}
return(final);
}
