# Coverage for pygeodesy/clipy.py : 94%

## 198 statements 186 run 12 missing 8 excluded

Hot-keys on this page

r m x p toggle line displays

j k next/prev highlighted chunk

0 (zero) top of page

1 (one) first highlighted chunk

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 | # -*- coding: utf-8 -*- u'''Functions to I{clip} a path or polygon of C{LatLon} points against a rectangular box or clip region. @newfield example: Example, Examples ''' from pygeodesy.fmath import EPS, fsum_, len2 from pygeodesy.formy import points2 from pygeodesy.lazily import _ALL_LAZY from pygeodesy.named import ClipCS3Tuple, ClipSH3Tuple from pygeodesy.points import _imdex2, boundsOf, isclockwise, isconvex_, \ LatLon_ as LL_ __all__ = _ALL_LAZY.clipy __version__ = '19.10.19' def _eq(p1, p2): # near-equal points return not _neq(p1, p2) def _neq(p1, p2): # not near-equal points return abs(p1.lat - p2.lat) > EPS or \ abs(p1.lon - p2.lon) > EPS class _CS(object): '''(INTERNAL) Cohen-Sutherland line clipping. ''' # single-bit codes _IN = 0 # inside clip box _YMIN = 1 # below lowerleft.lat _YMAX = 2 # above upperright.lat _XMIN = 4 # left of lowerleft.lon _XMAX = 8 # right of upperright.lon def __init__(self, lowerleft, upperright): self._ymin, self._ymax = lowerleft.lat, upperright.lat self._xmin, self._xmax = lowerleft.lon, upperright.lon if self._xmin > self._xmax or self._ymin > self._ymax: raise ValueError('%s invalid: %r to %r' % ( 'clip box', lowerleft, upperright)) self._y1 = self._dy = 0 self._x1 = self._dx = 0 # def clip4(self, p, c): # clip point p for code c # if c & _CS._YMIN: # return self.lon4(p, self._ymin) # elif c & _CS._YMAX: # return self.lon4(p, self._ymax) # elif c & _CS._XMIN: # return self.lat4(p, self._xmin) # elif c & _CS._XMAX: # return self.lat4(p, self._xmax) # # should never get here # raise AssertionError('clipCS3.clip2') def code4(self, p): # compute code for point p if p.lat < self._ymin: c, m, b = _CS._YMIN, self.lon4, self._ymin elif p.lat > self._ymax: c, m, b = _CS._YMAX, self.lon4, self._ymax else: c, m, b = _CS._IN, self.nop4, None if p.lon < self._xmin: c |= _CS._XMIN m, b = self.lat4, self._xmin elif p.lon > self._xmax: c |= _CS._XMAX m, b = self.lat4, self._xmax return c, m, b, p def edge(self, p1, p2): # set edge p1 to p2 self._y1, self._dy = p1.lat, float(p2.lat - p1.lat) self._x1, self._dx = p1.lon, float(p2.lon - p1.lon) return abs(self._dx) > EPS or abs(self._dy) > EPS def lat4(self, x, p): # new lat and code at lon x y = self._y1 + self._dy * float(x - self._x1) / self._dx if y < self._ymin: # still outside return _CS._YMIN, self.lon4, self._ymin, p elif y > self._ymax: # still outside return _CS._YMAX, self.lon4, self._ymax, p else: # inside return _CS._IN, self.nop4, None, p.classof(y, x) def lon4(self, y, p): # new lon and code at lat y x = self._x1 + self._dx * float(y - self._y1) / self._dy if x < self._xmin: # still outside return _CS._XMIN, self.lat4, self._xmin, p elif x > self._xmax: # still outside return _CS._XMAX, self.lat4, self._xmax, p else: # inside return _CS._IN, self.nop4, None, p.classof(y, x) def nop4(self, b, p): if p: # should never get here raise AssertionError('clipCS3.nop4') return _CS._IN, self.nop4, b, p def clipCS3(points, lowerleft, upperright, closed=False, inull=False): # MCCABE 25 '''Clip a path against a rectangular clip box using the U{Cohen-Sutherland <https://WikiPedia.org/wiki/Cohen-Sutherland_algorithm>} algorithm. @param points: The points (C{LatLon}[]). @param lowerleft: Bottom-left corner of the clip box (C{LatLon}). @param upperright: Top-right corner of the clip box (C{LatLon}). @keyword closed: Optionally, close the path (C{bool}). @keyword inull: Optionally, include null edges if inside (C{bool}). @return: Yield a L{ClipCS3Tuple}C{(start, end, index)} for each edge of the clipped path. @raise ValueError: The B{C{lowerleft}} corner is not below and/or not to the left of the B{C{upperright}} corner. ''' cs = _CS(lowerleft, upperright) n, points = points2(points, closed=closed) i, m = _imdex2(closed, n) cmbp = cs.code4(points[i]) for i in range(m, n): c1, m1, b1, p1 = cmbp c2, m2, b2, p2 = cmbp = cs.code4(points[i]) if c1 & c2: # edge outside continue if not cs.edge(p1, p2): if inull: # null edge if not c1: yield ClipCS3Tuple(p1, p1, i) elif not c2: yield ClipCS3Tuple(p2, p2, i) continue for _ in range(5): if c1: # clip p1 c1, m1, b1, p1 = m1(b1, p1) elif c2: # clip p2 c2, m2, b2, p2 = m2(b2, p2) else: # inside if inull or _neq(p1, p2): yield ClipCS3Tuple(p1, p2, i) break if c1 & c2: # edge outside break else: # should never get here raise AssertionError('clipCS3.for _') class _LLi_(LL_): '''(INTERNAL) LatLon_ for _SH intersections. ''' __slots__ = 'lat', 'lon', 'classof', 'edge', 'name' def __init__(self, lat, lon, classof, edge): self.lat = lat self.lon = lon self.classof = classof self.edge = edge # clip edge self.name = '' class _SH(object): '''(INTERNAL) Sutherland-Hodgman polyon clipping. ''' def __init__(self, corners): n = '' try: n, cs = len2(corners) if n == 2: # make a box b, l, t, r = boundsOf(cs, wrap=False) cs = LL_(b, l), LL_(t, l), LL_(t, r), LL_(b, r) n, cs = points2(cs, closed=True) self._corners = cs = cs[:n] self._nc = n self._cw = 1 if isclockwise(cs, adjust=False, wrap=False) else -1 if self._cw != isconvex_(cs, adjust=False, wrap=False): raise ValueError except ValueError: raise ValueError('%s[%s] invalid: %r' % ('corners', n, corners)) self._clipped = self._points = [] def append(self, p, inull): # save a clipped point if inull or (not self._clipped) or _neq(p, self._clipped[-1]): self._clipped.append(p) def clip(self, points, inull, closed): # MCCABE 19, clip points np, self._points = len2(points) if np > 0: # initial points, opened p = self._points[0] while np > 1 and _eq(self._points[np - 1], p): np -= 1 if np < 3: raise ValueError('too few %s: %s' % ('points', np)) no = ni = True # all out- or inside? for e in self.clips(): # clip the points, closed d2, p2 = self.dot2(np - 1) for i in range(np): d1, p1 = d2, p2 d2, p2 = self.dot2(i) if d1 < 0: # p1 inside, ... # self.append(p1, False, e) if d2 < 0: # ... p2 inside self.append(p2, inull) else: # ... p2 outside p = self.intersect(p1, p2, e) self.append(p, inull) if d2 > 0: no = False elif d2 < 0: # p1 out-, p2 inside p = self.intersect(p1, p2, e) self.append(p, inull) self.append(p2, inull) if d1 > 0: no = ni = False elif d1 > 0: ni = False if self._clipped: # replace points self._points = self._clipped self._clipped = [] np = len(self._points) # no is True iff all points are on or at one # side (left or right) of each clip edge, # ni is True iff all points are on or on the # right side (i.e. inside) of all clip edges if no and not ni: self._points = () np = 0 elif np > 1: p = self._points[0] if closed: # close clipped polygon if _neq(self._points[np - 1], p): self._points.append(p) np += 1 elif not inull: # open clipped polygon while np > 0 and _eq(self._points[np - 1], p): np -= 1 return np def clipped2(self, i): # return (clipped point[i], edge) p = self._points[i] if isinstance(p, _LLi_): # intersection point return p.classof(p.lat, p.lon), p.edge else: # original point return p, 0 def clips(self): # yield clip edge index c2 = self._corners[self._nc - 1] for i in range(self._nc): c1, c2 = c2, self._corners[i] self._y1, self._dy = c1.lat, float(c2.lat - c1.lat) self._x1, self._dx = c1.lon, float(c2.lon - c1.lon) if abs(self._dx) > EPS or abs(self._dy) > EPS: self._xy = self._y1 * self._dx - self._x1 * self._dy yield i + 1 def dot2(self, i): # dot product of points[i] to the current # clip corner c1 and clip edge c1 to c2, indicating whether # points[i] is located to the right, to the left or on the # (extended) clip edge from c1 to c2 p = self._points[i] d = self._dx * float(p.lat - self._y1) - \ self._dy * float(p.lon - self._x1) # clockwise corners, +1 means points[i] is to the right # of, -1 means on the left of, 0 means on edge c1 to c2 d = self._cw if d > 0 else (-self._cw if d < 0 else 0) return d, p def intersect(self, p1, p2, edge): # compute intersection # of polygon edge p1 to p2 and the current clip edge, # where p1 and p2 are known to NOT be located on the # same side of or on the current clip edge # <https://StackOverflow.com/questions/563198/ # how-do-you-detect-where-two-line-segments-intersect> fy = float(p2.lat - p1.lat) fx = float(p2.lon - p1.lon) fp = fy * self._dx - fx * self._dy if abs(fp) < EPS: raise AssertionError('clipSH.intersect') h = fsum_(self._xy, -p1.lat * self._dx, p1.lon * self._dy) / fp y = p1.lat + h * fy x = p1.lon + h * fx return _LLi_(y, x, p1.classof, edge) def clipSH(points, corners, inull=False, closed=False): '''Clip a polygon against a clip region or box using the U{Sutherland-Hodgman <https://WikiPedia.org/wiki/Sutherland_Hodgman_algorithm>} algorithm. @param points: The polygon points (C{LatLon}[]). @param corners: Three or more points defining a convex clip region (C{LatLon}[]) or two points to specify a rectangular clip box. @keyword inull: Optionally, include null edges (C{bool}). @keyword closed: Close the clipped points (C{bool}). @return: Yield the clipped points (C{LatLon}[]). @raise ValueError: Insufficient number of B{C{points}} or the B{C{corners}} specify a polar, zero-area, non-convex or otherwise invalid clip region. ''' sh = _SH(corners) n = sh.clip(points, inull, closed) for i in range(n): yield sh.clipped2(i)[0] def clipSH3(points, corners, inull=False, closed=False): '''Clip a polygon against a clip region or box using the U{Sutherland-Hodgman <https://WikiPedia.org/wiki/Sutherland_Hodgman_algorithm>} algorithm. @param points: The polygon points (C{LatLon}[]). @param corners: Three or more points defining a convex clip region (C{LatLon}[]) or two points to specify a rectangular clip box. @keyword inull: Optionally, include null edges (C{bool}). @keyword closed: Close the clipped points (C{bool}). @return: Yield a L{ClipSH3Tuple}C{(start, end, original)} for each edge of the clipped polygon. @raise ValueError: Insufficient number of B{C{points}} or the B{C{corners}} specify a polar, zero-area, non-convex or otherwise invalid clip region. ''' sh = _SH(corners) n = sh.clip(points, inull, closed) if n > 0: p2, e2 = sh.clipped2(0) for i in range(1, n): p1, e1 = p2, e2 p2, e2 = sh.clipped2(i) yield ClipSH3Tuple(p1, p2, not bool(e1 == e2 and e1 and e2)) # **) MIT License # # Copyright (C) 2018-2019 -- mrJean1 at Gmail dot com # # Permission is hereby granted, free of charge, to any person obtaining a # copy of this software and associated documentation files (the "Software"), # to deal in the Software without restriction, including without limitation # the rights to use, copy, modify, merge, publish, distribute, sublicense, # and/or sell copies of the Software, and to permit persons to whom the # Software is furnished to do so, subject to the following conditions: # # The above copyright notice and this permission notice shall be included # in all copies or substantial portions of the Software. # # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS # OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, # FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL # THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR # OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, # ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR # OTHER DEALINGS IN THE SOFTWARE.