Function nbCurve

cadquery/occ_impl/nurbs.py:607–663

NURBS book A3.1 with modifications to handle periodicity. Parameters ---------- u : Array Parameter values. order : int B-spline order. knots : Array Knot vector. pts : Array Control points. periodic : bool, optional Periodici

(
    u: Array, order: int, knots: Array, pts: Array, periodic: bool = False
)

@njit
def nbCurve(
    u: Array, order: int, knots: Array, pts: Array, periodic: bool = False
) -> Array:
    """
    NURBS book A3.1 with modifications to handle periodicity.

    Parameters
    ----------
    u : Array
        Parameter values.
    order : int
        B-spline order.
    knots : Array
        Knot vector.
    pts : Array
        Control points.
    periodic : bool, optional
        Periodicity flag. The default is False.

    Returns
    -------
    Array
        Curve values.

    """

    # number of control points
    nb = pts.shape[0]

    u_, knots_ext, minspan, maxspan, deltaspan = _preprocess(u, order, knots, periodic)

    # number of param values
    nu = np.size(u)

    # chunk size
    n = order + 1

    # temp chunk storage
    temp = np.zeros(n)

    # initialize
    out = np.zeros((nu, 3))

    for i in range(nu):
        ui = u_[i]

        # find span
        span = nbFindSpan(ui, order, knots, minspan, maxspan) + deltaspan

        # evaluate chunk
        nbBasis(span, ui, order, knots_ext, temp)

        # multiply by ctrl points
        for j in range(order + 1):
            out[i, :] += temp[j] * pts[(span - order + int(periodic) + j) % nb, :]

    return out