Coverage for pygeodesy/clipy.py: 96%
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2# -*- coding: utf-8 -*-
4u'''Clip a path or polygon of C{LatLon} points against a rectangular box or
5an arbitrary (convex) region.
7Box clip functions L{clipCS4} I{Cohen-Sutherland} and L{clipLB6} I{Liang-Barsky},
8region clip functions L{clipFHP4} I{Foster-Hormann-Popa}, L{clipGH4}
9I{Greiner-Hormann} and L{clipSH} and L{clipSH3} I{Sutherland-Hodgeman}.
10.
11'''
12# make sure int/int division yields float quotient, see .basics
13from __future__ import division as _; del _ # PYCHOK semicolon
15# from pygeodesy.basics import len2 # from .fmath
16from pygeodesy.constants import EPS, _0_0, _1_0
17from pygeodesy.errors import _AssertionError, ClipError, PointsError
18from pygeodesy.fmath import fabs, len2, Fsum
19# from pygeodesy.fsums import Fsum # from .fmath
20from pygeodesy.interns import NN, _clipid_, _convex_, _DOT_, _end_, _few_, \
21 _fi_, _height_, _i_, _invalid_, _j_, _lat_, \
22 _lon_, _near_, _not_, _points_, _start_, _too_
23from pygeodesy.iters import _imdex2, points2
24from pygeodesy.lazily import _ALL_LAZY, _ALL_MODS as _MODS
25from pygeodesy.named import _Named, _NamedTuple, _Pass, Property_RO
26from pygeodesy.points import areaOf, boundsOf, isconvex_, LatLon_
27# from pygeodesy.props import Property_RO # from .named
28from pygeodesy.units import Bool, FIx, HeightX, Lat, Lon, Number_
30# from math import fabs # from .fmath
32__all__ = _ALL_LAZY.clipy
33__version__ = '23.09.20'
35_fj_ = 'fj'
36_original_ = 'original'
39def _box4(lowerleft, upperight, name):
40 '''(INTERNAL) Get the clip box edges.
42 @see: Class C{_Box} in .ellipsoidalBaseDI.py.
43 '''
44 try:
45 yb, yt = lowerleft.lat, upperight.lat
46 xl, xr = lowerleft.lon, upperight.lon
47 if xl > xr or yb > yt:
48 raise ValueError(_invalid_)
49 except (AttributeError, TypeError, ValueError) as x:
50 raise ClipError(name, 2, (lowerleft, upperight), cause=x)
51 return xl, yb, xr, yt
54def _4corners(corners):
55 '''(INTERNAL) Clip region or box.
56 '''
57 n, cs = len2(corners)
58 if n == 2: # make a box
59 yb, xl, yt, xr = boundsOf(cs, wrap=False)
60 cs = (LatLon_(yb, xl), LatLon_(yt, xl),
61 LatLon_(yt, xr), LatLon_(yb, xr))
62 return cs
65def _eq(p1, p2, eps=EPS):
66 '''(INTERNAL) Check for near-equal points.
67 '''
68 return not _neq(p1, p2, eps)
71def _neq(p1, p2, eps=EPS):
72 '''(INTERNAL) Check for not near-equal points.
73 '''
74 return fabs(p1.lat - p2.lat) > eps or \
75 fabs(p1.lon - p2.lon) > eps
78def _pts2(points, closed, inull):
79 '''(INTERNAL) Get the points to clip as a list.
80 '''
81 if closed and inull:
82 n, pts = len2(points)
83 # only remove the final, closing point
84 if n > 1 and _eq(pts[n-1], pts[0]):
85 n -= 1
86 pts = pts[:n]
87 if n < 2:
88 raise PointsError(points=n, txt=_too_(_few_))
89 else:
90 n, pts = points2(points, closed=closed)
91 return n, list(pts)
94class _CS(_Named):
95 '''(INTERNAL) Cohen-Sutherland line clipping.
96 '''
97 # single-bit clip codes
98 _IN = 0 # inside clip box
99 _XR = 1 # right of upperight.lon
100 _XL = 2 # left of lowerleft.lon
101 _YT = 4 # above upperight.lat
102 _YB = 8 # below lowerleft.lat
104 _dx = _0_0 # pts edge delta lon
105 _dy = _0_0 # pts edge delta lat
106 _x1 = _0_0 # pts corner
107 _y1 = _0_0 # pts corner
109 _xr = _0_0 # clip box upperight.lon
110 _xl = _0_0 # clip box lowerleft.lon
111 _yt = _0_0 # clip box upperight.lat
112 _yb = _0_0 # clip box lowerleft.lat
114 def __init__(self, lowerleft, upperight, name=__name__):
115 self._xl, self._yb, \
116 self._xr, self._yt = _box4(lowerleft, upperight, name)
117 self.name = name
119# def clip4(self, p, c): # clip point p for code c
120# if c & _CS._YB:
121# return self.lon4(p, self._yb)
122# elif c & _CS._YT:
123# return self.lon4(p, self._yt)
124# elif c & _CS._XL:
125# return self.lat4(p, self._xl)
126# elif c & _CS._XR:
127# return self.lat4(p, self._xr)
128# # should never get here
129# raise _AssertionError(self._DOT_(self.clip4.__name__))
131 def code4(self, p): # compute code for point p
132 if p.lat < self._yb:
133 c, m, b = _CS._YB, self.lon4, self._yb
134 elif p.lat > self._yt:
135 c, m, b = _CS._YT, self.lon4, self._yt
136 else:
137 c, m, b = _CS._IN, self.nop4, None
138 if p.lon < self._xl:
139 c |= _CS._XL
140 m, b = self.lat4, self._xl
141 elif p.lon > self._xr:
142 c |= _CS._XR
143 m, b = self.lat4, self._xr
144 return c, m, b, p
146 def edge(self, p1, p2): # set edge p1 to p2
147 self._y1, self._dy = p1.lat, float(p2.lat - p1.lat)
148 self._x1, self._dx = p1.lon, float(p2.lon - p1.lon)
149 return fabs(self._dx) > EPS or fabs(self._dy) > EPS
151 def lat4(self, x, p): # new lat and code at lon x
152 y = self._y1 + self._dy * float(x - self._x1) / self._dx
153 if y < self._yb: # still outside
154 return _CS._YB, self.lon4, self._yb, p
155 elif y > self._yt: # still outside
156 return _CS._YT, self.lon4, self._yt, p
157 else: # inside
158 return _CS._IN, self.nop4, None, p.classof(y, x)
160 def lon4(self, y, p): # new lon and code at lat y
161 x = self._x1 + self._dx * float(y - self._y1) / self._dy
162 if x < self._xl: # still outside
163 return _CS._XL, self.lat4, self._xl, p
164 elif x > self._xr: # still outside
165 return _CS._XR, self.lat4, self._xr, p
166 else: # inside
167 return _CS._IN, self.nop4, None, p.classof(y, x)
169 def nop4(self, b, p): # PYCHOK no cover
170 if p: # should never get here
171 raise _AssertionError(self._DOT_(self.nop4.__name__))
172 return _CS._IN, self.nop4, b, p
175class ClipCS4Tuple(_NamedTuple):
176 '''4-Tuple C{(start, end, i, j)} for each edge of a I{clipped}
177 path with the C{start} and C{end} points (C{LatLon}) of the
178 portion of the edge inside or on the clip box and the indices
179 C{i} and C{j} (C{int}) of the edge start and end points in
180 the original path.
181 '''
182 _Names_ = (_start_, _end_, _i_, _j_)
183 _Units_ = (_Pass, _Pass, Number_, Number_)
186def clipCS4(points, lowerleft, upperight, closed=False, inull=False):
187 '''Clip a path against a rectangular clip box using the U{Cohen-Sutherland
188 <https://WikiPedia.org/wiki/Cohen-Sutherland_algorithm>} algorithm.
190 @arg points: The points (C{LatLon}[]).
191 @arg lowerleft: Bottom-left corner of the clip box (C{LatLon}).
192 @arg upperight: Top-right corner of the clip box (C{LatLon}).
193 @kwarg closed: Optionally, close the path (C{bool}).
194 @kwarg inull: Optionally, retain null edges if inside (C{bool}).
196 @return: Yield a L{ClipCS4Tuple}C{(start, end, i, j)} for each
197 edge of the I{clipped} path.
199 @raise ClipError: The B{C{lowerleft}} and B{C{upperight}} corners
200 specify an invalid clip box.
202 @raise PointsError: Insufficient number of B{C{points}}.
203 '''
204 T4 = ClipCS4Tuple
205 cs = _CS(lowerleft, upperight, name=clipCS4.__name__)
206 n, pts = _pts2(points, closed, inull)
208 i, m = _imdex2(closed, n)
209 cmbp = cs.code4(pts[i])
210 for j in range(m, n):
211 c1, m1, b1, p1 = cmbp
212 c2, m2, b2, p2 = cmbp = cs.code4(pts[j])
213 if c1 & c2: # edge outside
214 pass
215 elif cs.edge(p1, p2):
216 for _ in range(5):
217 if c1: # clip p1
218 c1, m1, b1, p1 = m1(b1, p1)
219 elif c2: # clip p2
220 c2, m2, b2, p2 = m2(b2, p2)
221 else: # inside
222 if inull or _neq(p1, p2):
223 yield T4(p1, p2, i, j)
224 break
225 if c1 & c2: # edge outside
226 break
227 else: # PYCHOK no cover
228 raise _AssertionError(_DOT_(cs.name, 'for_else'))
230 elif inull and not c1: # null edge
231 yield T4(p1, p1, i, j)
232 elif inull and not c2:
233 yield T4(p2, p2, i, j)
235 i = j
238class ClipFHP4Tuple(_NamedTuple):
239 '''4-Tuple C{(lat, lon, height, clipid)} for each point of the
240 L{clipFHP4} result with the C{lat}-, C{lon}gitude, C{height}
241 and C{clipid} of the polygon or clip.
243 @note: The C{height} is a L{HeightX} instance if this point is
244 an intersection, otherwise a L{Height} or C{int(0)}.
245 '''
246 _Names_ = (_lat_, _lon_, _height_, _clipid_)
247 _Units_ = ( Lat, Lon, _Pass, Number_)
249 @Property_RO
250 def isintersection(self):
251 '''Is this an intersection?
252 '''
253 return isinstance(self.height, HeightX)
255 @Property_RO
256 def ispoint(self):
257 '''Is this an original (polygon) point?
258 '''
259 return not self.isintersection
262def clipFHP4(points, corners, closed=False, inull=False, raiser=False, eps=EPS):
263 '''Clip one or more polygons against a clip region or box using U{Forster-Hormann-Popa
264 <https://www.ScienceDirect.com/science/article/pii/S259014861930007X>}'s C++
265 implementation transcoded to pure Python.
267 @arg points: The polygon points and clips (C{LatLon}[]).
268 @arg corners: Three or more points defining the clip regions (C{LatLon}[])
269 or two points to specify a single, rectangular clip box.
270 @kwarg closed: If C{True}, close each result clip (C{bool}).
271 @kwarg inull: If C{True}, retain null edges in result clips (C{bool}).
272 @kwarg raiser: If C{True}, throw L{ClipError} exceptions (C{bool}).
273 @kwarg esp: Tolerance for eliminating null edges (C{degrees}, same units
274 as the B{C{points}} and B{C{corners}} coordinates).
276 @return: Yield a L{ClipFHP4Tuple}C{(lat, lon, height, clipid)} for each
277 clipped point. The result may consist of several clips, each
278 a (closed) polygon with a unique C{clipid}.
280 @raise ClipError: Insufficient B{C{points}} or B{C{corners}} or an open clip.
282 @see: U{Forster, Hormann and Popa<https://www.ScienceDirect.com/science/
283 article/pii/S259014861930007X>}, class L{BooleanFHP} and function
284 L{clipGH4}.
285 '''
286 P = _MODS.booleans._CompositeFHP(points, kind=_points_, raiser=raiser,
287 eps=eps, name__=clipFHP4)
288 Q = _4corners(corners)
289 return P._clip(Q, Union=False, Clas=ClipFHP4Tuple, closed=closed,
290 inull=inull, raiser=P._raiser, eps=eps)
293class ClipGH4Tuple(ClipFHP4Tuple):
294 '''4-Tuple C{(lat, lon, height, clipid)} for each point of the
295 L{clipGH4} result with the C{lat}-, C{lon}gitude, C{height}
296 and C{clipid} of the polygon or clip.
298 @note: The C{height} is a L{HeightX} instance if this is
299 an intersection, otherwise a L{Height} or C{int(0)}.
300 '''
301 _Names_ = ClipFHP4Tuple._Names_
302 _Units_ = ClipFHP4Tuple._Units_
305def clipGH4(points, corners, closed=False, inull=False, raiser=True, xtend=False, eps=EPS):
306 '''Clip one or more polygons against a clip region or box using the U{Greiner-Hormann
307 <http://www.Inf.USI.CH/hormann/papers/Greiner.1998.ECO.pdf>} algorithm, U{Correia
308 <https://GitHub.com/helderco/univ-polyclip>}'s implementation modified and extended.
310 @arg points: The polygon points and clips (C{LatLon}[]).
311 @arg corners: Three or more points defining the clip regions (C{LatLon}[])
312 or two points to specify a single, rectangular clip box.
313 @kwarg closed: If C{True}, close each result clip (C{bool}).
314 @kwarg inull: If C{True}, retain null edges in result clips (C{bool}).
315 @kwarg raiser: If C{True}, throw L{ClipError} exceptions (C{bool}).
316 @kwarg xtend: If C{True}, extend edges of I{degenerate cases}, an attempt
317 to handle the latter (C{bool}).
318 @kwarg esp: Tolerance for eliminating null edges (C{degrees}, same units
319 as the B{C{points}} and B{C{corners}} coordinates).
321 @return: Yield a L{ClipGH4Tuple}C{(lat, lon, height, clipid)} for each
322 clipped point. The result may consist of several clips, each
323 a (closed) polygon with a unique C{clipid}.
325 @raise ClipError: Insufficient B{C{points}} or B{C{corners}}, an open clip,
326 a I{degenerate case} or I{unhandled} intersection.
328 @note: To handle I{degenerate cases} like C{point-edge} and C{point-point}
329 intersections, use function L{clipFHP4}.
331 @see: U{Greiner-Hormann<https://WikiPedia.org/wiki/Greiner–Hormann_clipping_algorithm>},
332 U{Ionel Daniel Stroe<https://Davis.WPI.edu/~matt/courses/clipping/>}, I{Correia}'s
333 U{univ-polyclip<https://GitHub.com/helderco/univ-polyclip>}, class L{BooleanGH}
334 and function L{clipFHP4}.
335 '''
336 S = _MODS.booleans._CompositeGH(points, raiser=raiser, xtend=xtend, eps=eps,
337 name__=clipGH4, kind=_points_)
338 C = _4corners(corners)
339 return S._clip(C, False, False, Clas=ClipGH4Tuple, closed=closed, inull=inull,
340 raiser=S._raiser, xtend=S._xtend, eps=eps)
343def _LBtrim(p, q, t):
344 # Liang-Barsky trim t[0] or t[1]
345 if p < 0:
346 r = q / p
347 if r > t[1]:
348 return False # too far above
349 elif r > t[0]:
350 t[0] = r
351 elif p > 0:
352 r = q / p
353 if r < t[0]:
354 return False # too far below
355 elif r < t[1]:
356 t[1] = r
357 elif q < 0: # vertical or horizontal
358 return False # ... outside
359 return True
362class ClipLB6Tuple(_NamedTuple):
363 '''6-Tuple C{(start, end, i, fi, fj, j)} for each edge of the
364 I{clipped} path with the C{start} and C{end} points (C{LatLon})
365 of the portion of the edge inside or on the clip box, indices
366 C{i} and C{j} (both C{int}) of the original path edge start
367 and end points and I{fractional} indices C{fi} and C{fj}
368 (both L{FIx}) of the C{start} and C{end} points along the
369 edge of the original path.
371 @see: Class L{FIx} and function L{pygeodesy.fractional}.
372 '''
373 _Names_ = (_start_, _end_, _i_, _fi_, _fj_, _j_)
374 _Units_ = (_Pass, _Pass, Number_, _Pass, _Pass, Number_)
377def clipLB6(points, lowerleft, upperight, closed=False, inull=False):
378 '''Clip a path against a rectangular clip box using the U{Liang-Barsky
379 <https://www.CSE.UNT.edu/~renka/4230/LineClipping.pdf>} algorithm.
381 @arg points: The points (C{LatLon}[]).
382 @arg lowerleft: Bottom-left corner of the clip box (C{LatLon}).
383 @arg upperight: Top-right corner of the clip box (C{LatLon}).
384 @kwarg closed: Optionally, close the path (C{bool}).
385 @kwarg inull: Optionally, retain null edges if inside (C{bool}).
387 @return: Yield a L{ClipLB6Tuple}C{(start, end, i, fi, fj, j)} for
388 each edge of the I{clipped} path.
390 @raise ClipError: The B{C{lowerleft}} and B{C{upperight}} corners
391 specify an invalid clip box.
393 @raise PointsError: Insufficient number of B{C{points}}.
395 @see: U{Liang-Barsky Line Clipping<https://www.CS.Helsinki.FI/group/goa/
396 viewing/leikkaus/intro.html>}, U{Liang-Barsky line clipping algorithm
397 <https://www.Skytopia.com/project/articles/compsci/clipping.html>} and
398 U{Liang-Barsky algorithm<https://WikiPedia.org/wiki/Liang-Barsky_algorithm>}.
399 '''
400 xl, yb, \
401 xr, yt = _box4(lowerleft, upperight, clipLB6.__name__)
402 n, pts = _pts2(points, closed, inull)
404 T6 = ClipLB6Tuple
405 fin = n if closed else None # wrapping fi [n] to [0]
406 _LB = _LBtrim
408 i, m = _imdex2(closed, n)
409 for j in range(m, n):
410 p1 = pts[i]
411 y1 = p1.lat
412 x1 = p1.lon
414 p2 = pts[j]
415 dy = float(p2.lat - y1)
416 dx = float(p2.lon - x1)
417 if fabs(dx) > EPS or fabs(dy) > EPS:
418 # non-null edge pts[i]...pts[j]
419 t = [_0_0, _1_0]
420 if _LB(-dx, -xl + x1, t) and \
421 _LB( dx, xr - x1, t) and \
422 _LB(-dy, -yb + y1, t) and \
423 _LB( dy, yt - y1, t):
424 # clip edge pts[i]...pts[j]
425 # at fractions t[0] to t[1]
426 f, t = t
427 if f > _0_0: # EPS
428 p1 = p1.classof(y1 + f * dy,
429 x1 + f * dx)
430 fi = i + f
431 else:
432 fi = i
434 if (t - f) > EPS: # EPS0
435 if t < _1_0: # EPS1
436 p2 = p2.classof(y1 + t * dy,
437 x1 + t * dx)
438 fj = i + t
439 else:
440 fj = j
441 fi = FIx(fi, fin=fin)
442 fj = FIx(fj, fin=fin)
443 yield T6(p1, p2, i, fi, fj, j)
445 elif inull:
446 fi = FIx(fi, fin=fin)
447 yield T6(p1, p1, i, fi, fi, j)
448# else: # outside
449# pass
450 elif inull: # null edge
451 yield T6(p1, p2, i, FIx(i, fin=fin),
452 FIx(j, fin=fin), j)
453 i = j
456class _SH(_Named):
457 '''(INTERNAL) Sutherland-Hodgman polyon clipping.
458 '''
459 _cs = () # clip corners
460 _cw = 0 # counter-/clockwise
461 _ccw = 0 # clock-/counterwise
462 _dx = _0_0 # clip edge[e] delta lon
463 _dy = _0_0 # clip edge[e] delta lat
464 _nc = 0 # len(._cs)
465 _x1 = _0_0 # clip edge[e] lon origin
466 _xy = _0_0 # see .clipedges
467 _y1 = _0_0 # clip edge[e] lat origin
469 def __init__(self, corners, name=__name__):
470 n, cs = 0, corners
471 try: # check the clip box/region
472 cs = _4corners(cs)
473 n, cs = len2(cs)
474 n, cs = points2(cs, closed=True)
475 self._cs = cs = cs[:n]
476 self._nc = n
477 self._cw = isconvex_(cs, adjust=False, wrap=False)
478 if not self._cw:
479 raise ValueError(_not_(_convex_))
480 if areaOf(cs, adjust=True, radius=1, wrap=True) < EPS:
481 raise ValueError(NN(_near_, 'zero area'))
482 self._ccw = -self._cw
483 except (PointsError, TypeError, ValueError) as x:
484 raise ClipError(name, n, cs, cause=x)
485 self.name = name
487 def clip2(self, points, closed, inull): # MCCABE 13, clip points
488 np, pts = _pts2(points, closed, inull)
489 pcs = _SHlist(inull) # clipped points
490 _ap = pcs.append
491 _d2 = self.dot2
492 _in = self.intersect
494 ne = 0 # number of non-null clip edges
495 for e in self.clipedges():
496 ne += 1 # non-null clip edge
498 # clip points, closed always
499 d1, p1 = _d2(pts[np - 1])
500 for i in range(np):
501 d2, p2 = _d2(pts[i])
502 if d1 < 0: # p1 inside, p2 ...
503 # _ap(p1)
504 _ap(p2 if d2 < 0 else # ... in-
505 _in(p1, p2, e)) # ... outside
506 elif d2 < 0: # p1 out-, p2 inside
507 _ap(_in(p1, p2, e))
508 _ap(p2)
509# elif d1 > 0: # both outside
510# pass
511 d1, p1 = d2, p2
513 # replace points, in-place
514 pts[:] = pcs
515 pcs[:] = []
516 np = len(pts)
517 if not np: # all outside
518 break
519 else:
520 if ne < 3:
521 raise ClipError(self.name, ne, self._cs, txt=_too_(_few_))
523 if np > 1:
524 p = pts[0]
525 if closed: # close clipped pts
526 if _neq(pts[np - 1], p):
527 pts.append(p)
528 np += 1
529 elif not inull: # open clipped pts
530 while np > 0 and _eq(pts[np - 1], p):
531 pts.pop()
532 np -= 1
533 # assert len(pts) == np
534 return np, pts
536 def clipedges(self): # yield clip edge index
537 # and set self._x1, ._y1, ._dx, ._dy and
538 # ._xy for each non-null clip edge
539 nc = self._nc
540 cs = self._cs
541 c = cs[nc - 1]
542 for e in range(nc):
543 y, x, c = c.lat, c.lon, cs[e]
544 dy = float(c.lat - y)
545 dx = float(c.lon - x)
546 if fabs(dx) > EPS or fabs(dy) > EPS:
547 self._y1, self._dy = y, dy
548 self._x1, self._dx = x, dx
549 self._xy = y * dx - x * dy
550 yield e + 1
552 def clipped2(self, p): # return (clipped point [i], edge)
553 if isinstance(p, _SHlli): # intersection point
554 return p.classof(p.lat, p.lon), p.edge
555 else: # original point
556 return p, 0
558 def dot2(self, p): # dot product of point p to clip
559 # corner c1 and clip edge c1 to c2, indicating where
560 # point p is located: to the right, to the left or
561 # on top of the (extended) clip edge from c1 to c2
562 d = float(p.lat - self._y1) * self._dx - \
563 float(p.lon - self._x1) * self._dy
564 # clockwise corners, +1 means point p is to the right
565 # of, -1 means on the left of, 0 means on edge c1 to c2
566 d = self._ccw if d < 0 else (self._cw if d > 0 else 0)
567 return d, p
569 def intersect(self, p1, p2, edge): # compute intersection
570 # of polygon edge p1 to p2 and the current clip edge,
571 # where p1 and p2 are known to NOT be located on the
572 # same side of or on the current, non-null clip edge
573 # <https://StackOverflow.com/questions/563198/
574 # how-do-you-detect-where-two-line-segments-intersect>
575 y, dy = p1.lat, self._dy
576 x, dx = p1.lon, self._dx
577 fy = float(p2.lat - y)
578 fx = float(p2.lon - x)
579 d = fy * dx - fx * dy # fdot((fx, fy), dx, -dy)
580 if fabs(d) < EPS: # PYCHOK no cover
581 raise _AssertionError(self._DOT_(self.intersect.__name__))
582 d = Fsum(self._xy, -y * dx, x * dy).fover(d)
583 y += d * fy
584 x += d * fx
585 return _SHlli(y, x, p1.classof, edge)
588class _SHlist(list):
589 '''(INTERNAL) List of _SH clipped points.
590 '''
591 _inull = False
593 def __init__(self, inull):
594 self._inull = inull
595 list.__init__(self)
597 def append(self, p):
598 if (not self) or self._inull or _neq(p, self[-1]):
599 list.append(self, p)
602class _SHlli(LatLon_):
603 '''(INTERNAL) LatLon_ for _SH intersections.
604 '''
605 # __slots__ are no longer space savers, see
606 # the comments at the class .points.LatLon_
607 # __slots__ = _lat_, _lon_, 'classof', 'edge', _name_
609 def __init__(self, lat, lon, classof, edge):
610 self.lat = lat
611 self.lon = lon
612 self.classof = classof
613 self.edge = edge # clip edge
614 self.name = NN
617class ClipSH3Tuple(_NamedTuple):
618 '''3-Tuple C{(start, end, original)} for each edge of a I{clipped}
619 polygon, the C{start} and C{end} points (C{LatLon}) of the
620 portion of the edge inside or on the clip region and C{original}
621 indicates whether the edge is part of the original polygon or
622 part of the clip region (C{bool}).
623 '''
624 _Names_ = (_start_, _end_, _original_)
625 _Units_ = (_Pass, _Pass, Bool)
628def clipSH(points, corners, closed=False, inull=False):
629 '''Clip a polygon against a clip region or box using the U{Sutherland-Hodgman
630 <https://WikiPedia.org/wiki/Sutherland-Hodgman_algorithm>} algorithm.
632 @arg points: The polygon points (C{LatLon}[]).
633 @arg corners: Three or more points defining a convex clip
634 region (C{LatLon}[]) or two points to specify
635 a rectangular clip box.
636 @kwarg closed: Close the clipped points (C{bool}).
637 @kwarg inull: Optionally, include null edges (C{bool}).
639 @return: Yield the clipped points (C{LatLon}[]).
641 @raise ClipError: The B{C{corners}} specify a polar, zero-area,
642 non-convex or otherwise invalid clip box or
643 region.
645 @raise PointsError: Insufficient number of B{C{points}}.
646 '''
647 sh = _SH(corners, name=clipSH.__name__)
648 n, pts = sh.clip2(points, closed, inull)
649 for i in range(n):
650 p, _ = sh.clipped2(pts[i])
651 yield p
654def clipSH3(points, corners, closed=False, inull=False):
655 '''Clip a polygon against a clip region or box using the U{Sutherland-Hodgman
656 <https://WikiPedia.org/wiki/Sutherland-Hodgman_algorithm>} algorithm.
658 @arg points: The polygon points (C{LatLon}[]).
659 @arg corners: Three or more points defining a convex clip
660 region (C{LatLon}[]) or two points to specify
661 a rectangular clip box.
662 @kwarg closed: Close the clipped points (C{bool}).
663 @kwarg inull: Optionally, include null edges (C{bool}).
665 @return: Yield a L{ClipSH3Tuple}C{(start, end, original)} for
666 each edge of the I{clipped} polygon.
668 @raise ClipError: The B{C{corners}} specify a polar, zero-area,
669 non-convex or otherwise invalid clip box or
670 region.
672 @raise PointsError: Insufficient number of B{C{points}} or B{C{corners}}.
673 '''
674 sh = _SH(corners, name=clipSH3.__name__)
675 n, pts = sh.clip2(points, closed, inull)
676 if n > 1:
677 T3 = ClipSH3Tuple
678 p1, e1 = sh.clipped2(pts[0])
679 for i in range(1, n):
680 p2, e2 = sh.clipped2(pts[i])
681 yield T3(p1, p2, not bool(e1 and e2 and e1 == e2))
682 p1, e1 = p2, e2
684# **) MIT License
685#
686# Copyright (C) 2018-2025 -- mrJean1 at Gmail -- All Rights Reserved.
687#
688# Permission is hereby granted, free of charge, to any person obtaining a
689# copy of this software and associated documentation files (the "Software"),
690# to deal in the Software without restriction, including without limitation
691# the rights to use, copy, modify, merge, publish, distribute, sublicense,
692# and/or sell copies of the Software, and to permit persons to whom the
693# Software is furnished to do so, subject to the following conditions:
694#
695# The above copyright notice and this permission notice shall be included
696# in all copies or substantial portions of the Software.
697#
698# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
699# OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
700# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
701# THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
702# OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
703# ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
704# OTHER DEALINGS IN THE SOFTWARE.