import numpy as np
from math import degrees
from matplotlib import cbook
import math
[docs]def atan2(dy, dx):
if dx == 0 and dy == 0:
cbook._warn_external("dx and dy are 0")
return 0
else:
return math.atan2(dy, dx)
# FIXME : The current algorithm seems to return incorrect angle when the line
# ends at the boundary.
[docs]def clip(xlines, ylines, x0, clip="right", xdir=True, ydir=True):
clipped_xlines = []
clipped_ylines = []
_pos_angles = []
xsign = 1 if xdir else -1
ysign = 1 if ydir else -1
for x, y in zip(xlines, ylines):
if clip in ["up", "right"]:
b = (x < x0).astype("i")
db = b[1:] - b[:-1]
else:
b = (x > x0).astype("i")
db = b[1:] - b[:-1]
if b[0]:
ns = 0
else:
ns = -1
segx, segy = [], []
for (i,) in np.argwhere(db):
c = db[i]
if c == -1:
dx = (x0 - x[i])
dy = (y[i+1] - y[i]) * (dx / (x[i+1] - x[i]))
y0 = y[i] + dy
clipped_xlines.append(np.concatenate([segx, x[ns:i+1], [x0]]))
clipped_ylines.append(np.concatenate([segy, y[ns:i+1], [y0]]))
ns = -1
segx, segy = [], []
if dx == 0. and dy == 0:
dx = x[i+1] - x[i]
dy = y[i+1] - y[i]
a = degrees(atan2(ysign*dy, xsign*dx))
_pos_angles.append((x0, y0, a))
elif c == 1:
dx = (x0 - x[i])
dy = (y[i+1] - y[i]) * (dx / (x[i+1] - x[i]))
y0 = y[i] + dy
segx, segy = [x0], [y0]
ns = i+1
if dx == 0. and dy == 0:
dx = x[i+1] - x[i]
dy = y[i+1] - y[i]
a = degrees(atan2(ysign*dy, xsign*dx))
_pos_angles.append((x0, y0, a))
if ns != -1:
clipped_xlines.append(np.concatenate([segx, x[ns:]]))
clipped_ylines.append(np.concatenate([segy, y[ns:]]))
return clipped_xlines, clipped_ylines, _pos_angles
[docs]def clip_line_to_rect(xline, yline, bbox):
x0, y0, x1, y1 = bbox.extents
xdir = x1 > x0
ydir = y1 > y0
if x1 > x0:
lx1, ly1, c_right_ = clip([xline], [yline], x1,
clip="right", xdir=xdir, ydir=ydir)
lx2, ly2, c_left_ = clip(lx1, ly1, x0,
clip="left", xdir=xdir, ydir=ydir)
else:
lx1, ly1, c_right_ = clip([xline], [yline], x0,
clip="right", xdir=xdir, ydir=ydir)
lx2, ly2, c_left_ = clip(lx1, ly1, x1,
clip="left", xdir=xdir, ydir=ydir)
if y1 > y0:
ly3, lx3, c_top_ = clip(ly2, lx2, y1,
clip="right", xdir=ydir, ydir=xdir)
ly4, lx4, c_bottom_ = clip(ly3, lx3, y0,
clip="left", xdir=ydir, ydir=xdir)
else:
ly3, lx3, c_top_ = clip(ly2, lx2, y0,
clip="right", xdir=ydir, ydir=xdir)
ly4, lx4, c_bottom_ = clip(ly3, lx3, y1,
clip="left", xdir=ydir, ydir=xdir)
c_left = [((x, y), (a + 90) % 180 - 90) for x, y, a in c_left_
if bbox.containsy(y)]
c_bottom = [((x, y), (90 - a) % 180) for y, x, a in c_bottom_
if bbox.containsx(x)]
c_right = [((x, y), (a + 90) % 180 + 90) for x, y, a in c_right_
if bbox.containsy(y)]
c_top = [((x, y), (90 - a) % 180 + 180) for y, x, a in c_top_
if bbox.containsx(x)]
return list(zip(lx4, ly4)), [c_left, c_bottom, c_right, c_top]
