/// <summary>
/// Computes the knot vectors used to calculate a curve global interpolation.
/// </summary>
private static KnotVector ComputeKnotsForInterpolation(List <double> curveParameters, int degree, bool hasTangents)
{
// Start knot vectors.
KnotVector knots = CollectionHelpers.RepeatData(0.0, degree + 1).ToKnot();
// If we have tangent values we need two more control points and knots.
int start = (hasTangents) ? 0 : 1;
int end = (hasTangents) ? curveParameters.Count - degree + 1 : curveParameters.Count - degree;
// Use averaging method (Eqn 9.8) to compute internal knots in the knot vector.
for (int i = start; i < end; i++)
{
double weightSum = 0.0;
for (int j = 0; j < degree; j++)
{
weightSum += curveParameters[i + j];
}
knots.Add((1.0 / degree) * weightSum);
}
// Add end knot vectors.
knots.AddRange(CollectionHelpers.RepeatData(1.0, degree + 1));
return(knots);
}
/// <summary>
/// Computes the knots vectors used to calculate an approximate curve.
/// </summary>
private static KnotVector ComputeKnotsForCurveApproximation(List <double> curveParameters, int degree, int numberOfCtrPts, int numberOfPts)
{
// Start knot vectors.
KnotVector knots = CollectionHelpers.RepeatData(0.0, degree + 1).ToKnot();
// Compute 'd' value - Eqn 9.68.
double d = (double)numberOfPts / (numberOfCtrPts - degree);
// Find the internal knots - Eqn 9.69.
for (int j = 1; j < numberOfCtrPts - degree; j++)
{
int i = (int)(j * d);
double alpha = (j * d) - i;
double knot = ((1.0 - alpha) * curveParameters[i - 1]) + (alpha * curveParameters[i]);
knots.Add(knot);
}
// Add end knot vectors.
knots.AddRange(CollectionHelpers.RepeatData(1.0, degree + 1));
return(knots);
}
