Function nbBasis

cadquery/occ_impl/nurbs.py:457–496

NURBS book A2.2 Parameters ---------- i : int Span index. u : float Parameter value. order : int B-spline order. knots : ndarray Knot vector. out : ndarray B-spline basis function values. Returns ------- None.

(i: int, u: float, order: int, knots: Array, out: Array)

@njiti
def nbBasis(i: int, u: float, order: int, knots: Array, out: Array):
    """
    NURBS book A2.2

    Parameters
    ----------
    i : int
        Span index.
    u : float
        Parameter value.
    order : int
        B-spline order.
    knots : ndarray
        Knot vector.
    out : ndarray
        B-spline basis function values.

    Returns
    -------
    None.

    """

    out[0] = 1.0

    left = np.zeros_like(out)
    right = np.zeros_like(out)

    for j in range(1, order + 1):
        left[j] = u - knots[i + 1 - j]
        right[j] = knots[i + j] - u

        saved = 0.0

        for r in range(j):
            temp = out[r] / (right[r + 1] + left[j - r])
            out[r] = saved + right[r + 1] * temp
            saved = left[j - r] * temp

        out[j] = saved


@njiti