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simplify cut_polygon_with_line()

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This commit is contained in:
Laura Klünder 2017-11-13 17:09:26 +01:00
parent 47ff4fe788
commit bcdc77d2b2
1 changed files with 73 additions and 66 deletions
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23
src/c3nav/mapdata/utils/geometry.py
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@ -154,7 +154,12 @@ def cut_polygon_with_line(polygon: Polygon, line: LineString):
last = points.popleft()
while points:
current = points.popleft()
if current.polygon == last.polygon:
# don't to anything between different polygons
if current.polygon != last.polygon:
last = current
continue
polygon = polygons[current.polygon]
segment = cut_line_with_point(cut_line_with_point(line, last.point)[-1], current.point)[0]
if current.ring != last.ring:
@ -179,10 +184,10 @@ def cut_polygon_with_line(polygon: Polygon, line: LineString):
points = deque((cutpoint(item.point, item.polygon, mapping[item.ring])
if (item.polygon == current.polygon and item.ring in mapping) else item)
for item in points)
current = cutpoint(current.point, current.polygon, new_i)
last = cutpoint(current.point, current.polygon, new_i)
continue
elif current.ring == 0:
# cut polygon
# cut polygon?
new_i = len(polygons)
exterior = cut_line_with_point(polygon[0], current.point)
exterior = cut_line_with_point(LinearRing(exterior[1].coords[:-1] +
@ -203,8 +208,11 @@ def cut_polygon_with_line(polygon: Polygon, line: LineString):
while angle_segment > angle_forwards:
angle_segment -= 2*math.pi
# cut polygon only if segment is inside polygon
if angle_backwards < angle_segment < angle_forwards:
# don't cut polygon if segment is not inside polygon (= we don't cut through emptyness)
if not (angle_backwards < angle_segment < angle_forwards):
last = current
continue
exterior1 = LinearRing(exterior[0].coords[:-1] + segment.coords[0:])
exterior2 = LinearRing(exterior[1].coords[:-1] + segment.coords[::-1])
geom = Polygon(exterior1)
@ -224,7 +232,6 @@ def cut_polygon_with_line(polygon: Polygon, line: LineString):
if (item.polygon == current.polygon and item.ring == 0 and
not exterior1.contains(item.point)) else item)
for item in points)
current = cutpoint(current.point, new_i, 0)
last = current
last = cutpoint(current.point, new_i, 0)
return tuple(Polygon(polygon[0], tuple(ring for ring in polygon[1:] if ring is not None))
for polygon in polygons)