bezier.py 文件源码

def polynomial2bezier(poly):
    """Converts a cubic or lower order Polynomial object (or a sequence of
    coefficients) to a CubicBezier, QuadraticBezier, or Line object as
    appropriate."""
    if isinstance(poly, poly1d):
        c = poly.coeffs
    else:
        c = poly
    order = len(c)-1
    if order == 3:
        bpoints = (c[3], c[2]/3 + c[3], (c[1] + 2*c[2])/3 + c[3],
                   c[0] + c[1] + c[2] + c[3])
    elif order == 2:
        bpoints = (c[2], c[1]/2 + c[2], c[0] + c[1] + c[2])
    elif order == 1:
        bpoints = (c[1], c[0] + c[1])
    else:
        raise AssertionError("This function is only implemented for linear, "
                             "quadratic, and cubic polynomials.")
    return bpoints


# Curve Splitting #############################################################