public static IEnumerable <PrimitiveBezier> SplineToBezierCurves(Spline spline)
{
if (spline == null)
{
throw new ArgumentNullException(nameof(spline));
}
var expectedIdenticalKnots = spline.Degree + 1;
var builder = new SplineBuilder(spline.Degree, spline.ControlPoints, spline.KnotValues);
for (int offset = 0; ; offset++)
{
// get next set of values
var values = builder.KnotValues.Skip(offset * expectedIdenticalKnots).Take(expectedIdenticalKnots).ToList();
if (values.Count == 0 && builder.KnotValues.Count() % expectedIdenticalKnots == 0)
{
// done
break;
}
var expectedValue = values[0];
int missingValueCount;
if (values.Count < expectedIdenticalKnots)
{
// not enough values
missingValueCount = expectedIdenticalKnots - values.Count;
}
else if (values.Count < expectedIdenticalKnots || values.Any(v => v != expectedValue))
{
// not all the same
missingValueCount = expectedIdenticalKnots - values.Count(v => v == expectedValue);
}
else
{
missingValueCount = 0;
}
for (int i = 0; i < missingValueCount; i++)
{
builder.InsertKnot(expectedValue);
}
}
var points = builder.ControlPoints.ToList();
var curves = new List <PrimitiveBezier>();
for (int startIndex = 0; startIndex < points.Count; startIndex += expectedIdenticalKnots)
{
var curve = PrimitiveBezier.FromPoints(points, startIndex, expectedIdenticalKnots);
curves.Add(curve);
}
return(curves);
}
public Spline(int degree, IEnumerable <Point> controlPoints, IEnumerable <double> knotValues, CadColor?color = null, object tag = null)
: base(color, tag)
{
if (controlPoints == null)
{
throw new ArgumentNullException(nameof(controlPoints));
}
if (knotValues == null)
{
throw new ArgumentNullException(nameof(knotValues));
}
if (degree != 3)
{
throw new NotImplementedException("Only cubic splines are currently supported.");
}
Degree = degree;
ControlPoints = controlPoints.ToArray();
KnotValues = knotValues.ToArray();
if (KnotValues.Length != ControlPoints.Length + Degree + 1)
{
throw new InvalidOperationException("The number of knot values must be one greater than the sum of the number of control points and the degree of the curve.");
}
_snapPoints = new[]
{
new EndPoint(ControlPoints[0]),
new EndPoint(ControlPoints[ControlPoints.Length - 1])
};
_beziers = SplineBuilder.SplineToBezierCurves(this).ToArray();
BoundingBox = BoundingBox.Includes(_beziers.Select(b => b.GetBoundingBox()));
}
