Returns a cubic Catmull–Rom curve factory with the specified alpha in the range [0, 1].
If alpha is zero, produces a uniform spline, equivalent to curveCardinal with a tension of zero;
if alpha is one, produces a chordal spline; if alpha is 0.5, produces a centripetal spline.
Centripetal splines are recommended to avoid self-intersections and overshoot.
Returns a cubic Catmull–Rom curve factory with the specified alpha in the range [0, 1]. If alpha is zero, produces a uniform spline, equivalent to curveCardinal with a tension of zero; if alpha is one, produces a chordal spline; if alpha is 0.5, produces a centripetal spline. Centripetal splines are recommended to avoid self-intersections and overshoot.