API Reference > geometry-core > Bspline > BSplineCurve3dBase > fractionToPointAndDerivative fractionToPointAndDerivative Method Construct a ray with origin at the fractional position along the arc direction is the first derivative, i.e. tangent along the curve fractionToPointAndDerivative(fraction: number, result?: Ray3d): Ray3d Parameter Type Description fraction number result Ray3d Returns - Ray3d Defined in core/geometry/src/bspline/BSplineCurve.ts Line 131 Last Updated: 13 June, 2024