# Coverage for pygeodesy/clipy.py : 96%

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Clip a path or polygon of C{LatLon} points against a rectangular box or a (convex) clip region. ''' from pygeodesy.basics import len2 from pygeodesy.errors import _AssertionError, PointsError, _ValueError from pygeodesy.fmath import fsum_ from pygeodesy.interns import EPS, NN, _convex_, _DOT_, _end_, \ _few_, _i_, _j_, _not_, _SPACE_, \ _start_, _too_, _0_0, _1_0 from pygeodesy.iters import _imdex2, points2 from pygeodesy.lazily import _ALL_LAZY from pygeodesy.named import _Named, _NamedTuple, _Pass from pygeodesy.points import areaOf, boundsOf, isconvex_, LatLon_ from pygeodesy.units import Bool, FIx, Number_ __all__ = _ALL_LAZY.clipy __version__ = '21.07.02' _fi_ = 'fi' _fj_ = 'fj' class ClipError(_ValueError): '''Clip box or clip region issue. ''' def __init__(self, *name_n_corners, **txt): '''New L{ClipError}. @arg name_n_corners: Either just a name (C{str}) or name, number, corners (C{str}, C{int}, C{tuple}). @kwarg txt: Optional explanation of the error (C{str}). ''' if len(name_n_corners) == 3: t, n, v = name_n_corners n = _SPACE_(t, 'clip', 'box' if n == 2 else 'region') name_n_corners = n, v _ValueError.__init__(self, *name_n_corners, **txt) def _box4(lowerleft, upperright, name): '''(INTERNAL) Get the clip box edges. ''' try: ymin, ymax = lowerleft.lat, upperright.lat xmin, xmax = lowerleft.lon, upperright.lon if xmin > xmax or ymin > ymax: raise ValueError except (AttributeError, TypeError, ValueError) as x: raise ClipError(name, 2, (lowerleft, upperright), txt=str(x)) return xmin, ymin, xmax, ymax def _eq(p1, p2): '''(INTERNAL) Check for near-equal points. ''' return not _neq(p1, p2) def _neq(p1, p2): '''(INTERNAL) Check for not near-equal points. ''' return abs(p1.lat - p2.lat) > EPS or \ abs(p1.lon - p2.lon) > EPS def _pts2(points, closed, inull): '''(INTERNAL) Get the points to clip. ''' if closed and inull: n, pts = len2(points) # only remove the final, closing point if n > 1 and _eq(pts[n-1], pts[0]): n -= 1 pts = pts[:n] if n < 2: raise PointsError(points=n, txt=_too_(_few_)) else: n, pts = points2(points, closed=closed) return n, list(pts) class _CS(_Named): '''(INTERNAL) Cohen-Sutherland line clipping. ''' # single-bit clip codes _IN = 0 # inside clip box _XMAX = 1 # right of upperright.lon _XMIN = 2 # left of lowerleft.lon _YMAX = 4 # above upperright.lat _YMIN = 8 # below lowerleft.lat _dx = _0_0 # pts edge delta lon _dy = _0_0 # pts edge delta lat _x1 = _0_0 # pts corner _y1 = _0_0 # pts corner _xmax = _0_0 # clip box upperright.lon _xmin = _0_0 # clip box lowerleft.lon _ymax = _0_0 # clip box upperright.lat _ymin = _0_0 # clip box lowerleft.lat def __init__(self, lowerleft, upperright, name=__name__): self._xmin, self._ymin, \ self._xmax, self._ymax = _box4(lowerleft, upperright, name) self.name = name # 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(self._DOT_(self.clip4.__name__)) 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): # PYCHOK no cover if p: # should never get here raise _AssertionError(self._DOT_(self.nop4.__name__)) return _CS._IN, self.nop4, b, p class ClipCS4Tuple(_NamedTuple): '''4-Tuple C{(start, end, i, j)} for each edge of a I{clipped} path with the C{start} and C{end} points (C{LatLon}) of the portion of the edge inside or on the clip box and the indices C{i} and C{j} (C{int}) of the edge start and end points in the original path. ''' _Names_ = (_start_, _end_, _i_, _j_) _Units_ = (_Pass, _Pass, Number_, Number_) def clipCS4(points, lowerleft, upperright, closed=False, inull=False): '''Clip a path against a rectangular clip box using the U{Cohen-Sutherland <https://WikiPedia.org/wiki/Cohen-Sutherland_algorithm>} algorithm. @arg points: The points (C{LatLon}[]). @arg lowerleft: Bottom-left corner of the clip box (C{LatLon}). @arg upperright: Top-right corner of the clip box (C{LatLon}). @kwarg closed: Optionally, close the path (C{bool}). @kwarg inull: Optionally, retain null edges if inside (C{bool}). @return: Yield a L{ClipCS4Tuple}C{(start, end, i, j)} for each edge of the I{clipped} path. @raise ClipError: The B{C{lowerleft}} and B{C{upperright}} corners specify an invalid clip box. @raise PointsError: Insufficient number of B{C{points}}. ''' cs = _CS(lowerleft, upperright, name=clipCS4.__name__) n, pts = _pts2(points, closed, inull) i, m = _imdex2(closed, n) cmbp = cs.code4(pts[i]) for j in range(m, n): c1, m1, b1, p1 = cmbp c2, m2, b2, p2 = cmbp = cs.code4(pts[j]) if c1 & c2: # edge outside pass elif cs.edge(p1, p2): 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 ClipCS4Tuple(p1, p2, i, j) break if c1 & c2: # edge outside break else: # PYCHOK no cover raise _AssertionError(_DOT_(cs.name, 'for_else')) elif inull and not c1: # null edge yield ClipCS4Tuple(p1, p1, i, j) elif inull and not c2: yield ClipCS4Tuple(p2, p2, i, j) i = j class ClipLB6Tuple(_NamedTuple): '''6-Tuple C{(start, end, i, fi, fj, j)} for each edge of the I{clipped} path with the C{start} and C{end} points (C{LatLon}) of the portion of the edge inside or on the clip box, indices C{i} and C{j} (C{int}) of the original path edge start and end points and I{fractional} indices C{fi} and C{fj} (L{FIx}) of the C{start} and C{end} points along the edge of the original path. @see: Class L{FIx} and function L{fractional}. ''' _Names_ = (_start_, _end_, _i_, _fi_, _fj_, _j_) _Units_ = (_Pass, _Pass, Number_, _Pass, _Pass, Number_) def clipLB6(points, lowerleft, upperright, closed=False, inull=False): '''Clip a path against a rectangular clip box using the U{Liang-Barsky <https://www.CSE.UNT.edu/~renka/4230/LineClipping.pdf>} algorithm. @arg points: The points (C{LatLon}[]). @arg lowerleft: Bottom-left corner of the clip box (C{LatLon}). @arg upperright: Top-right corner of the clip box (C{LatLon}). @kwarg closed: Optionally, close the path (C{bool}). @kwarg inull: Optionally, retain null edges if inside (C{bool}). @return: Yield a L{ClipLB6Tuple}C{(start, end, i, fi, fj, j)} for each edge of the I{clipped} path. @raise ClipError: The B{C{lowerleft}} and B{C{upperright}} corners specify an invalid clip box. @raise PointsError: Insufficient number of B{C{points}}. @see: U{Liang-Barsky Line Clipping<https://www.CS.Helsinki.FI/group/goa/ viewing/leikkaus/intro.html>}, U{Liang-Barsky line clipping algorithm <https://www.Skytopia.com/project/articles/compsci/clipping.html>} and U{Liang-Barsky algorithm<https://WikiPedia.org/wiki/Liang-Barsky_algorithm>}. ''' xmin, ymin, \ xmax, ymax = _box4(lowerleft, upperright, clipLB6.__name__) n, pts = _pts2(points, closed, inull) fin = n if closed else None # wrapping fi [n] to [0] _LB = _LBtrim i, m = _imdex2(closed, n) for j in range(m, n): p1 = pts[i] y1 = p1.lat x1 = p1.lon p2 = pts[j] dy = float(p2.lat - y1) dx = float(p2.lon - x1) if abs(dx) > EPS or abs(dy) > EPS: # non-null edge pts[i]...pts[j] t = [_0_0, _1_0] if _LB(-dx, -xmin + x1, t) and \ _LB( dx, xmax - x1, t) and \ _LB(-dy, -ymin + y1, t) and \ _LB( dy, ymax - y1, t): # clip edge pts[i]...pts[j] # at fractions t[0] to t[1] f, t = t if f > _0_0: # EPS p1 = p1.classof(y1 + f * dy, x1 + f * dx) fi = i + f else: fi = i if (t - f) > EPS: # EPS0 if t < _1_0: # EPS1 p2 = p2.classof(y1 + t * dy, x1 + t * dx) fj = i + t else: fj = j fi = FIx(fi, fin=fin) fj = FIx(fj, fin=fin) yield ClipLB6Tuple(p1, p2, i, fi, fj, j) elif inull: fi = FIx(fi, fin=fin) yield ClipLB6Tuple(p1, p1, i, fi, fi, j) # else: # outside # pass elif inull: # null edge yield ClipLB6Tuple(p1, p2, i, FIx(i, fin=fin), FIx(j, fin=fin), j) i = j def _LBtrim(p, q, t): # Liang-Barsky trim t[0] or t[1] if p < 0: r = q / p if r > t[1]: return False # too far above elif r > t[0]: t[0] = r elif p > 0: r = q / p if r < t[0]: return False # too far below elif r < t[1]: t[1] = r elif q < 0: # vertical or horizontal return False # ... outside return True class _List(list): '''(INTERNAL) List of clipped points. ''' _inull = False def __init__(self, inull): self._inull = inull list.__init__(self) def append(self, p): if (not self) or self._inull or _neq(p, self[-1]): list.append(self, p) class _LLi_(LatLon_): '''(INTERNAL) LatLon_ for _SH intersections. ''' # __slots__ are no longer space savers, see # the comments at the class .points.LatLon_ # __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 = NN class _SH(_Named): '''(INTERNAL) Sutherland-Hodgman polyon clipping. ''' _cs = () # clip corners _cw = 0 # counter-/clockwise _dx = _0_0 # clip edge[e] delta lon _dy = _0_0 # clip edge[e] delta lat _nc = 0 # len(._cs) _x1 = _0_0 # clip edge[e] lon origin _xy = _0_0 # see .clipedges _y1 = _0_0 # clip edge[e] lat origin def __init__(self, corners, name=__name__): n, cs = 0, corners try: # check the clip box/region n, cs = len2(cs) if n == 2: # make a box b, l, t, r = boundsOf(cs, wrap=False) cs = (LatLon_(b, l), LatLon_(t, l), LatLon_(t, r), LatLon_(b, r)) n, cs = points2(cs, closed=True) self._cs = cs = cs[:n] self._nc = n self._cw = isconvex_(cs, adjust=False, wrap=False) if not self._cw: raise ValueError(_not_(_convex_)) if areaOf(cs, adjust=True, radius=1, wrap=True) < EPS: raise ValueError('near-zero area') except (PointsError, TypeError, ValueError) as x: raise ClipError(name, n, cs, txt=str(x)) self.name = name def clip2(self, points, closed, inull): # MCCABE 17, clip points np, pts = _pts2(points, closed, inull) pcs = _List(inull) # clipped points ne = 0 # number of non-null clip edges no = ni = True # all out- and inside? for e in self.clipedges(): ne += 1 # non-null clip edge # clip points, closed always d2, p2 = self.dot2(pts[np - 1]) for i in range(np): d1, p1 = d2, p2 d2, p2 = self.dot2(pts[i]) if d1 < 0: # p1 inside, ... # pcs.append(p1) if d2 < 0: # ... p2 inside p = p2 else: # ... p2 outside p = self.intersect(p1, p2, e) if d2 > 0: no = False pcs.append(p) elif d2 < 0: # p1 out-, p2 inside p = self.intersect(p1, p2, e) pcs.append(p) pcs.append(p2) if d1 > 0: no = ni = False elif d1 > 0: # both out ni = False if pcs: # replace points pts[:] = pcs pcs[:] = [] np = len(pts) if ne < 3: raise ClipError(self.name, ne, self._cs, txt=_too_(_few_)) # ni is True iff all points are on or on the # right side (i.e. inside) of all clip edges, # no is True iff all points are on or at one # side (left or right) of each clip edge: if # none are inside (ni is False) and if all # are on the same side (no is True), then all # must be outside if no and not ni: np, pts = 0, [] elif np > 1: p = pts[0] if closed: # close clipped pts if _neq(pts[np - 1], p): pts.append(p) np += 1 elif not inull: # open clipped pts while np > 0 and _eq(pts[np - 1], p): pts.pop() np -= 1 # assert len(pts) == np return np, pts def clipedges(self): # yield clip edge index # and set self._x1, ._y1, ._dx, ._dy and # ._xy for each non-null clip edge c2 = self._cs[self._nc - 1] for e in range(self._nc): c1, c2 = c2, self._cs[e] 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 e + 1 def clipped2(self, p): # return (clipped point [i], edge) if isinstance(p, _LLi_): # intersection point return p.classof(p.lat, p.lon), p.edge else: # original point return p, 0 def dot2(self, p): # dot product of point p to the current # clip corner c1 and clip edge c1 to c2, indicating whether # point p is located to the right, to the left or on top # of the (extended) clip edge from c1 to c2 d = self._dx * float(p.lat - self._y1) - \ self._dy * float(p.lon - self._x1) # clockwise corners, +1 means point p 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 or on top of 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: # PYCHOK no cover raise _AssertionError(self._DOT_(self.intersect.__name__)) r = fsum_(self._xy, -p1.lat * self._dx, p1.lon * self._dy) / fp y = p1.lat + r * fy x = p1.lon + r * fx return _LLi_(y, x, p1.classof, edge) class ClipSH3Tuple(_NamedTuple): '''3-Tuple C{(start, end, original)} for each edge of a I{clipped} polygon, the C{start} and C{end} points (C{LatLon}) of the portion of the edge inside or on the clip region and C{original} indicates whether the edge is part of the original polygon or part of the clip region (C{bool}). ''' _Names_ = (_start_, _end_, 'original') _Units_ = (_Pass, _Pass, Bool) def clipSH(points, corners, closed=False, inull=False): '''Clip a polygon against a clip region or box using the U{Sutherland-Hodgman <https://WikiPedia.org/wiki/Sutherland_Hodgman_algorithm>} algorithm. @arg points: The polygon points (C{LatLon}[]). @arg corners: Three or more points defining a convex clip region (C{LatLon}[]) or two points to specify a rectangular clip box. @kwarg closed: Close the clipped points (C{bool}). @kwarg inull: Optionally, include null edges (C{bool}). @return: Yield the clipped points (C{LatLon}[]). @raise ClipError: The B{C{corners}} specify a polar, zero-area, non-convex or otherwise invalid clip box or region. @raise PointsError: Insufficient number of B{C{points}}. ''' sh = _SH(corners, name=clipSH.__name__) n, pts = sh.clip2(points, closed, inull) for i in range(n): yield sh.clipped2(pts[i])[0] def clipSH3(points, corners, closed=False, inull=False): '''Clip a polygon against a clip region or box using the U{Sutherland-Hodgman <https://WikiPedia.org/wiki/Sutherland_Hodgman_algorithm>} algorithm. @arg points: The polygon points (C{LatLon}[]). @arg corners: Three or more points defining a convex clip region (C{LatLon}[]) or two points to specify a rectangular clip box. @kwarg closed: Close the clipped points (C{bool}). @kwarg inull: Optionally, include null edges (C{bool}). @return: Yield a L{ClipSH3Tuple}C{(start, end, original)} for each edge of the I{clipped} polygon. @raise ClipError: The B{C{corners}} specify a polar, zero-area, non-convex or otherwise invalid clip box or region. @raise PointsError: Insufficient number of B{C{points}}. ''' sh = _SH(corners, name=clipSH3.__name__) n, pts = sh.clip2(points, closed, inull) if n > 0: p2, e2 = sh.clipped2(pts[0]) for i in range(1, n): p1, e1 = p2, e2 p2, e2 = sh.clipped2(pts[i]) yield ClipSH3Tuple(p1, p2, not bool(e1 and e2 and e1 == e2)) # **) MIT License # # Copyright (C) 2018-2021 -- mrJean1 at Gmail -- All Rights Reserved. # # 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.