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Add keyword-argument hack for 2/3 as well

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This commit is contained in:
Behdad Esfahbod 2016-07-28 13:44:41 -07:00
parent d357503806
commit 77c913ba61
1 changed files with 9 additions and 7 deletions
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16
Lib/cu2qu/__init__.py
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@ -147,12 +147,14 @@ def cubic_farthest_fit(p0, p1, p2, p3, tolerance):
_cubic_farthest_fit(mid, mid+deriv3, (p2+p3)*.5, p3, tolerance))
def cubic_approx_spline(cubic, n, tolerance):
def cubic_approx_spline(cubic, n, tolerance, _2_3=2/3):
"""Approximate a cubic bezier curve with a spline of n quadratics.
Returns None if no quadratic approximation is found which lies entirely
within a distance `tolerance` from the original curve.
"""
# we define 2/3 as a keyword argument so that it will be evaluated only
# once but still in the scope of this function
# special-case single-segment spline using intersection of ab and cd
if n == 1:
@ -161,8 +163,8 @@ def cubic_approx_spline(cubic, n, tolerance):
return None
c0 = cubic[0]
c3 = cubic[3]
c1 = c0 + (q1 - c0) * (2/3)
c2 = c3 + (q1 - c3) * (2/3)
c1 = c0 + (q1 - c0) * _2_3
c2 = c3 + (q1 - c3) * _2_3
if not cubic_farthest_fit(0,
c1 - cubic[1],
c2 - cubic[2],
@ -192,10 +194,10 @@ def cubic_approx_spline(cubic, n, tolerance):
q0, q1, q2 = q2, spline[i], (spline[i] + spline[i + 1]) * .5
c0, c1, c2, c3 = segments[i - 1]
if not cubic_farthest_fit(q0 - c0,
q0 + (q1 - q0) * (2/3) - c1,
q2 + (q1 - q2) * (2/3) - c2,
q2 - c3,
if not cubic_farthest_fit(q0 - c0,
q0 + (q1 - q0) * _2_3 - c1,
q2 + (q1 - q2) * _2_3 - c2,
q2 - c3,
tolerance):
return None