added "examples" folder

pull/7/merge
Andy 2017-03-30 02:22:23 -07:00
parent 385dbb7196
commit dcd4896fd6
3 changed files with 112 additions and 0 deletions

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"""The goal of this gist is to show how to compute many points on a path
quickly using NumPy arrays. I.e. there's a much faster way than using, say
[some_path.point(t) for t in many_tvals]. The example below assumes the
`Path` object is composed entirely of `CubicBezier` objects, but this can
easily be generalized to paths containing `Line` and `QuadraticBezier` objects
also.
Note: The relevant matrix transformation for quadratics can be found in the
svgpathtools.bezier module."""
import numpy as np
from svgpathtools import *
class HigherOrderBezier:
def __init__(self, bpoints):
self.bpts = bpoints
def bpoints(self):
return self.bpts
def point(self, t):
return bezier_point(self.bpoints(), t)
def __repr__(self):
return str(self.bpts)
def random_bezier(degree):
if degree <= 3:
return bpoints2bezier(polynomial2bezier(np.random.rand(degree + 1)))
else:
return HigherOrderBezier(np.random.rand(degree + 1))
def points_in_each_seg_slow(path, tvals):
return [seg.poly()(tvals) for seg in path]
def points_in_each_seg(path, tvals):
"""Compute seg.point(t) for each seg in path and each t in tvals."""
A = np.matrix([[-1, 3, -3, 1], # transforms cubic bez to standard poly
[ 3, -6, 3, 0],
[-3, 3, 0, 0],
[ 1, 0, 0, 0]])
B = [seg.bpoints() for seg in path]
return np.dot(B, np.dot(A, np.power(tvals, [[3],[2],[1],[0]])))
if __name__ == '__main__':
num_segs = 1000
testpath = Path(*[random_bezier(3) for dummy in range(num_segs)])
tvals = np.linspace(0, 1, 10)
pts = points_in_each_seg(testpath, tvals)
pts_check = points_in_each_seg_slow(testpath, tvals)
print np.max(pts - pts_check)

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"""
An example of how to determine if an svg path is contained in another
svg path in Python.
Note: for discontinuous paths you can use the svgpathtools
Path.continuous_subpaths() method to split a paths into a list of its
continuous subpaths.
"""
from svgpathtools import *
def path1_is_contained_in_path2(path1, path2):
assert path2.isclosed() # This question isn't well-defined otherwise
if path2.intersect(path1):
return False
# find a point that's definitely outside path2
xmin, xmax, ymin, ymax = path2.bbox()
B = (xmin + 1) + 1j*(ymax + 1)
A = path1.start # pick an arbitrary point in path1
AB_line = Path(Line(A, B))
number_of_intersections = len(AB_line.intersect(path2))
if number_of_intersections % 2: # if number of intersections is odd
return True
else:
return False
# Test examples
closed_path = Path(Line(0,5), Line(5,5+5j), Line(5+5j, 0))
path_that_is_contained = Path(Line(1+1j, 2+2j))
print(path1_is_contained_in_path2(path_that_is_contained, closed_path))
path_thats_not_contained = Path(Line(10+10j, 20+20j))
print(path1_is_contained_in_path2(path_thats_not_contained, closed_path))
path_that_intersects = Path(Line(2+1j, 10+10j))
print(path1_is_contained_in_path2(path_that_intersects, closed_path))

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from svgpathtools import *
# create some example paths
path1 = CubicBezier(1,2+3j,3-5j,4+1j)
path2 = path1.rotated(60).translated(3)
# find minimizer
from scipy.optimize import fminbound
def dist(t):
return path1.radialrange(path2.point(t))[0][0]
T2 = fminbound(dist, 0, 1)
# Let's do a visual check
pt2 = path2.point(T2)
T1 = path1.radialrange(pt2)[0][1]
pt1 = path1.point(T1)
disvg([path1, path2, Line(pt1, pt2)], 'grb', nodes=[pt1, pt2])