def __init__(self, points):
self.output = [] # list of line segment
self.arc = None # binary tree for parabola arcs
self.points = PriorityQueue() # site events
self.event = PriorityQueue() # circle events
# bounding box
self.x0 = -50.0
self.x1 = -50.0
self.y0 = 550.0
self.y1 = 550.0
# insert points to site event
for pts in points:
point = Point(pts[0], pts[1])
self.points.push(point)
# keep track of bounding box size
if point.x < self.x0: self.x0 = point.x
if point.y < self.y0: self.y0 = point.y
if point.x > self.x1: self.x1 = point.x
if point.y > self.y1: self.y1 = point.y
# add margins to the bounding box
dx = (self.x1 - self.x0 + 1) / 5.0
dy = (self.y1 - self.y0 + 1) / 5.0
self.x0 = self.x0 - dx
self.x1 = self.x1 + dx
self.y0 = self.y0 - dy
self.y1 = self.y1 + dy
def __init__(self, points):
self.output = [] # list of line segment
self.arc = None # binary tree for parabola arcs
self.points = PriorityQueue() # site events
self.event = PriorityQueue() # circle events
# bounding box
self.x0 = -50.0
self.x1 = -50.0
self.y0 = 550.0
self.y1 = 550.0
# insert points to site event
for pts in points:
point = Point(pts[0], pts[1])
self.points.push(point)
# keep track of bounding box size
if point.x < self.x0: self.x0 = point.x
if point.y < self.y0: self.y0 = point.y
if point.x > self.x1: self.x1 = point.x
if point.y > self.y1: self.y1 = point.y
# add margins to the bounding box
dx = (self.x1 - self.x0 + 1) / 5.0
dy = (self.y1 - self.y0 + 1) / 5.0
self.x0 = self.x0 - dx
self.x1 = self.x1 + dx
self.y0 = self.y0 - dy
self.y1 = self.y1 + dy
def __init__(self, points):
self.voronoi = []
self.beach_line = None
self.scenes = []
self.points = points
self.events = PriorityQueue()
# bounding box
self.LEFT = -50
self.RIGHT = -50
self.TOP = 500
self.BOTTOM = 500
self.create_bounding_box(points)
class Voronoi:
def __init__(self, points):
self.output = [] # list of line segment
self.arc = None # binary tree for parabola arcs
self.points = PriorityQueue() # site events
self.event = PriorityQueue() # circle events
# bounding box
self.x0 = -50.0
self.x1 = -50.0
self.y0 = 550.0
self.y1 = 550.0
# insert points to site event
for pts in points:
point = Point(pts[0], pts[1])
self.points.push(point)
# keep track of bounding box size
if point.x < self.x0: self.x0 = point.x
if point.y < self.y0: self.y0 = point.y
if point.x > self.x1: self.x1 = point.x
if point.y > self.y1: self.y1 = point.y
# add margins to the bounding box
dx = (self.x1 - self.x0 + 1) / 5.0
dy = (self.y1 - self.y0 + 1) / 5.0
self.x0 = self.x0 - dx
self.x1 = self.x1 + dx
self.y0 = self.y0 - dy
self.y1 = self.y1 + dy
def process(self):
while not self.points.empty():
if not self.event.empty() and (self.event.top().x <= self.points.top().x):
self.process_event() # handle circle event
else:
self.process_point() # handle site event
# after all points, process remaining circle events
while not self.event.empty():
self.process_event()
self.finish_edges()
def process_point(self):
# get next event from site pq
p = self.points.pop()
# add new arc (parabola)
self.arc_insert(p)
def process_event(self):
# get next event from circle pq
e = self.event.pop()
if e.valid:
# start new edge
s = Segment(e.p)
self.output.append(s)
# remove associated arc (parabola)
a = e.a
if a.pprev is not None:
a.pprev.pnext = a.pnext
a.pprev.s1 = s
if a.pnext is not None:
a.pnext.pprev = a.pprev
a.pnext.s0 = s
# finish the edges before and after a
if a.s0 is not None: a.s0.finish(e.p)
if a.s1 is not None: a.s1.finish(e.p)
# recheck circle events on either side of p
if a.pprev is not None: self.check_circle_event(a.pprev, e.x)
if a.pnext is not None: self.check_circle_event(a.pnext, e.x)
def arc_insert(self, p):
if self.arc is None:
self.arc = Arc(p)
else:
# find the current arcs at p.y
i = self.arc
while i is not None:
flag, z = self.intersect(p, i)
if flag:
# new parabola intersects arc i
flag, zz = self.intersect(p, i.pnext)
if (i.pnext is not None) and (not flag):
i.pnext.pprev = Arc(i.p, i, i.pnext)
i.pnext = i.pnext.pprev
else:
i.pnext = Arc(i.p, i)
i.pnext.s1 = i.s1
# add p between i and i.pnext
i.pnext.pprev = Arc(p, i, i.pnext)
i.pnext = i.pnext.pprev
i = i.pnext # now i points to the new arc
# add new half-edges connected to i's endpoints
seg = Segment(z)
self.output.append(seg)
i.pprev.s1 = i.s0 = seg
seg = Segment(z)
self.output.append(seg)
i.pnext.s0 = i.s1 = seg
# check for new circle events around the new arc
self.check_circle_event(i, p.x)
self.check_circle_event(i.pprev, p.x)
self.check_circle_event(i.pnext, p.x)
return
i = i.pnext
# if p never intersects an arc, append it to the list
i = self.arc
while i.pnext is not None:
i = i.pnext
i.pnext = Arc(p, i)
# insert new segment between p and i
x = self.x0
y = (i.pnext.p.y + i.p.y) / 2.0;
start = Point(x, y)
seg = Segment(start)
i.s1 = i.pnext.s0 = seg
self.output.append(seg)
def check_circle_event(self, i, x0):
# look for a new circle event for arc i
if (i.e is not None) and (i.e.x != self.x0):
i.e.valid = False
i.e = None
if (i.pprev is None) or (i.pnext is None): return
flag, x, o = self.circle(i.pprev.p, i.p, i.pnext.p)
if flag and (x > self.x0):
i.e = Event(x, o, i)
self.event.push(i.e)
def circle(self, a, b, c):
# check if bc is a "right turn" from ab
if ((b.x - a.x)*(c.y - a.y) - (c.x - a.x)*(b.y - a.y)) > 0: return False, None, None
# Joseph O'Rourke, Computational Geometry in C (2nd ed.) p.189
A = b.x - a.x
B = b.y - a.y
C = c.x - a.x
D = c.y - a.y
E = A*(a.x + b.x) + B*(a.y + b.y)
F = C*(a.x + c.x) + D*(a.y + c.y)
G = 2*(A*(c.y - b.y) - B*(c.x - b.x))
if (G == 0): return False, None, None # Points are co-linear
# point o is the center of the circle
ox = 1.0 * (D*E - B*F) / G
oy = 1.0 * (A*F - C*E) / G
# o.x plus radius equals max x coord
x = ox + math.sqrt((a.x-ox)**2 + (a.y-oy)**2)
o = Point(ox, oy)
return True, x, o
def intersect(self, p, i):
# check whether a new parabola at point p intersect with arc i
if (i is None): return False, None
if (i.p.x == p.x): return False, None
a = 0.0
b = 0.0
if i.pprev is not None:
a = (self.intersection(i.pprev.p, i.p, 1.0*p.x)).y
if i.pnext is not None:
b = (self.intersection(i.p, i.pnext.p, 1.0*p.x)).y
if (((i.pprev is None) or (a <= p.y)) and ((i.pnext is None) or (p.y <= b))):
py = p.y
px = 1.0 * ((i.p.x)**2 + (i.p.y-py)**2 - p.x**2) / (2*i.p.x - 2*p.x)
res = Point(px, py)
return True, res
return False, None
def intersection(self, p0, p1, l):
# get the intersection of two parabolas
p = p0
if (p0.x == p1.x):
py = (p0.y + p1.y) / 2.0
elif (p1.x == l):
py = p1.y
elif (p0.x == l):
py = p0.y
p = p1
else:
# use quadratic formula
z0 = 2.0 * (p0.x - l)
z1 = 2.0 * (p1.x - l)
a = 1.0/z0 - 1.0/z1
b = -2.0 * (p0.y/z0 - p1.y/z1)
c = 1.0 * (p0.y**2 + p0.x**2 - l**2) / z0 - 1.0 * (p1.y**2 + p1.x**2 - l**2) / z1
py = 1.0 * (-b-math.sqrt(b*b - 4*a*c)) / (2*a)
px = 1.0 * (p.x**2 + (p.y-py)**2 - l**2) / (2*p.x-2*l)
res = Point(px, py)
return res
def finish_edges(self):
l = self.x1 + (self.x1 - self.x0) + (self.y1 - self.y0)
i = self.arc
while i.pnext is not None:
if i.s1 is not None:
p = self.intersection(i.p, i.pnext.p, l*2.0)
i.s1.finish(p)
i = i.pnext
def print_output(self):
it = 0
for o in self.output:
it = it + 1
p0 = o.start
p1 = o.end
print (p0.x, p0.y, p1.x, p1.y)
def get_output(self):
res = []
for o in self.output:
p0 = o.start
p1 = o.end
res.append((p0.x, p0.y, p1.x, p1.y))
return res
class Voronoi:
def __init__(self, points):
self.output = [] # list of line segment
self.arc = None # binary tree for parabola arcs
self.points = PriorityQueue() # site events
self.event = PriorityQueue() # circle events
# bounding box
self.x0 = -50.0
self.x1 = -50.0
self.y0 = 550.0
self.y1 = 550.0
# insert points to site event
for pts in points:
point = Point(pts[0], pts[1])
self.points.push(point)
# keep track of bounding box size
if point.x < self.x0: self.x0 = point.x
if point.y < self.y0: self.y0 = point.y
if point.x > self.x1: self.x1 = point.x
if point.y > self.y1: self.y1 = point.y
# add margins to the bounding box
dx = (self.x1 - self.x0 + 1) / 5.0
dy = (self.y1 - self.y0 + 1) / 5.0
self.x0 = self.x0 - dx
self.x1 = self.x1 + dx
self.y0 = self.y0 - dy
self.y1 = self.y1 + dy
def process(self):
while not self.points.empty():
if not self.event.empty() and (self.event.top().x <= self.points.top().x):
self.process_event() # handle circle event
else:
self.process_point() # handle site event
# after all points, process remaining circle events
while not self.event.empty():
self.process_event()
self.finish_edges()
def process_point(self):
# get next event from site pq
p = self.points.pop()
# add new arc (parabola)
self.arc_insert(p)
def process_event(self):
# get next event from circle pq
e = self.event.pop()
if e.valid:
# start new edge
s = Segment(e.p)
self.output.append(s)
# remove associated arc (parabola)
a = e.a
if a.pprev is not None:
a.pprev.pnext = a.pnext
a.pprev.s1 = s
if a.pnext is not None:
a.pnext.pprev = a.pprev
a.pnext.s0 = s
# finish the edges before and after a
if a.s0 is not None: a.s0.finish(e.p)
if a.s1 is not None: a.s1.finish(e.p)
# recheck circle events on either side of p
if a.pprev is not None: self.check_circle_event(a.pprev, e.x)
if a.pnext is not None: self.check_circle_event(a.pnext, e.x)
def arc_insert(self, p):
if self.arc is None:
self.arc = Arc(p)
else:
# find the current arcs at p.y
i = self.arc
while i is not None:
flag, z = self.intersect(p, i)
if flag:
# new parabola intersects arc i
flag, zz = self.intersect(p, i.pnext)
if (i.pnext is not None) and (not flag):
i.pnext.pprev = Arc(i.p, i, i.pnext)
i.pnext = i.pnext.pprev
else:
i.pnext = Arc(i.p, i)
i.pnext.s1 = i.s1
# add p between i and i.pnext
i.pnext.pprev = Arc(p, i, i.pnext)
i.pnext = i.pnext.pprev
i = i.pnext # now i points to the new arc
# add new half-edges connected to i's endpoints
seg = Segment(z)
self.output.append(seg)
i.pprev.s1 = i.s0 = seg
seg = Segment(z)
self.output.append(seg)
i.pnext.s0 = i.s1 = seg
# check for new circle events around the new arc
self.check_circle_event(i, p.x)
self.check_circle_event(i.pprev, p.x)
self.check_circle_event(i.pnext, p.x)
return
i = i.pnext
# if p never intersects an arc, append it to the list
i = self.arc
while i.pnext is not None:
i = i.pnext
i.pnext = Arc(p, i)
# insert new segment between p and i
x = self.x0
y = (i.pnext.p.y + i.p.y) / 2.0;
start = Point(x, y)
seg = Segment(start)
i.s1 = i.pnext.s0 = seg
self.output.append(seg)
def check_circle_event(self, i, x0):
# look for a new circle event for arc i
if (i.e is not None) and (i.e.x <> self.x0):
i.e.valid = False
i.e = None
if (i.pprev is None) or (i.pnext is None): return
flag, x, o = self.circle(i.pprev.p, i.p, i.pnext.p)
if flag and (x > self.x0):
i.e = Event(x, o, i)
self.event.push(i.e)
def circle(self, a, b, c):
# check if bc is a "right turn" from ab
if ((b.x - a.x)*(c.y - a.y) - (c.x - a.x)*(b.y - a.y)) > 0: return False, None, None
# Joseph O'Rourke, Computational Geometry in C (2nd ed.) p.189
A = b.x - a.x
B = b.y - a.y
C = c.x - a.x
D = c.y - a.y
E = A*(a.x + b.x) + B*(a.y + b.y)
F = C*(a.x + c.x) + D*(a.y + c.y)
G = 2*(A*(c.y - b.y) - B*(c.x - b.x))
if (G == 0): return False, None, None # Points are co-linear
# point o is the center of the circle
ox = 1.0 * (D*E - B*F) / G
oy = 1.0 * (A*F - C*E) / G
# o.x plus radius equals max x coord
x = ox + math.sqrt((a.x-ox)**2 + (a.y-oy)**2)
o = Point(ox, oy)
return True, x, o
def intersect(self, p, i):
# check whether a new parabola at point p intersect with arc i
if (i is None): return False, None
if (i.p.x == p.x): return False, None
a = 0.0
b = 0.0
if i.pprev is not None:
a = (self.intersection(i.pprev.p, i.p, 1.0*p.x)).y
if i.pnext is not None:
b = (self.intersection(i.p, i.pnext.p, 1.0*p.x)).y
if (((i.pprev is None) or (a <= p.y)) and ((i.pnext is None) or (p.y <= b))):
py = p.y
px = 1.0 * ((i.p.x)**2 + (i.p.y-py)**2 - p.x**2) / (2*i.p.x - 2*p.x)
res = Point(px, py)
return True, res
return False, None
def intersection(self, p0, p1, l):
# get the intersection of two parabolas
p = p0
if (p0.x == p1.x):
py = (p0.y + p1.y) / 2.0
elif (p1.x == l):
py = p1.y
elif (p0.x == l):
py = p0.y
p = p1
else:
# use quadratic formula
z0 = 2.0 * (p0.x - l)
z1 = 2.0 * (p1.x - l)
a = 1.0/z0 - 1.0/z1;
b = -2.0 * (p0.y/z0 - p1.y/z1)
c = 1.0 * (p0.y**2 + p0.x**2 - l**2) / z0 - 1.0 * (p1.y**2 + p1.x**2 - l**2) / z1
py = 1.0 * (-b-math.sqrt(b*b - 4*a*c)) / (2*a)
px = 1.0 * (p.x**2 + (p.y-py)**2 - l**2) / (2*p.x-2*l)
res = Point(px, py)
return res
def finish_edges(self):
l = self.x1 + (self.x1 - self.x0) + (self.y1 - self.y0)
i = self.arc
while i.pnext is not None:
if i.s1 is not None:
p = self.intersection(i.p, i.pnext.p, l*2.0)
i.s1.finish(p)
i = i.pnext
def print_output(self):
it = 0
for o in self.output:
it = it + 1
p0 = o.start
p1 = o.end
print (p0.x, p0.y, p1.x, p1.y)
def get_output(self):
res = []
for o in self.output:
p0 = o.start
p1 = o.end
res.append((p0.x, p0.y, p1.x, p1.y))
return res
class Fortune:
def __init__(self, points):
self.voronoi = []
self.beach_line = None
self.scenes = []
self.points = points
self.events = PriorityQueue()
# bounding box
self.LEFT = -50
self.RIGHT = -50
self.TOP = 500
self.BOTTOM = 500
self.create_bounding_box(points)
def create_bounding_box(self, points):
for pts in points:
point = Point(pts[0], pts[1])
self.events.push(point)
if point.x < self.LEFT:
self.LEFT = point.x
if point.y < self.TOP:
self.TOP = point.y
if point.x > self.RIGHT:
self.RIGHT = point.x
if point.y > self.BOTTOM:
self.BOTTOM = point.y
dx = (self.RIGHT - self.LEFT + 1) / 5.0
dy = (self.BOTTOM - self.TOP + 1) / 5.0
self.LEFT = self.LEFT - dx
self.RIGHT = self.RIGHT + dx
self.TOP = self.TOP - dy
self.BOTTOM = self.BOTTOM + dy
def calculate_voronoi_diagram(self):
while not self.events.empty():
event = self.events.pop()
if isinstance(event, Circle):
self.handle_circle_event(event)
else:
self.handle_point_event(event)
self.finish_edges()
def calculate_voronoi_diagram_with_visualization(self):
while not self.events.empty():
event = self.events.pop()
if isinstance(event, Circle):
self.handle_circle_event(event)
else:
self.handle_point_event(event)
self.scenes.append(
Scene([
PointsCollection(self.points, color='red'),
PointsCollection(self.get_voronoi_points(), color='blue')
], [LinesCollection(self.get_voronoi_lines())]))
self.finish_edges_with_visualization()
def handle_point_event(self, point):
self.insert_arc(point)
def handle_circle_event(self, circle_event):
if circle_event.valid:
edge = Edge(circle_event.point)
self.voronoi.append(edge)
arc = circle_event.beach_line
if arc.prev is not None:
arc.prev.next = arc.next
arc.prev.lower_edge = edge
if arc.next is not None:
arc.next.prev = arc.prev
arc.next.upper_edge = edge
if arc.upper_edge is not None:
arc.upper_edge.finish(circle_event.point)
if arc.lower_edge is not None:
arc.lower_edge.finish(circle_event.point)
if arc.prev is not None:
self.check_circle_event(arc.prev)
if arc.next is not None:
self.check_circle_event(arc.next)
def insert_arc(self, point):
if self.beach_line is None:
self.beach_line = Arc(point)
return
if self.insert_arc_among_existing(point):
return
arc = self.beach_line
while arc.next is not None:
arc = arc.next
arc.next = Arc(point, arc)
x = self.LEFT
y = (arc.next.point.y + arc.point.y) / 2.0
start = Point(x, y)
edge = Edge(start)
arc.lower_edge = arc.next.upper_edge = edge
self.voronoi.append(edge)
def insert_arc_among_existing(self, point):
arc = self.beach_line
while arc is not None:
intersection_point = check_if_arc_intersects(point, arc)
if intersection_point is not None:
second_intersection_point = check_if_arc_intersects(
point, arc.next)
if arc.next is not None and second_intersection_point is None:
arc.next.prev = Arc(arc.point, arc, arc.next)
arc.next = arc.next.prev
else:
arc.next = Arc(arc.point, arc)
arc.next.lower_edge = arc.lower_edge
arc.next.prev = Arc(point, arc, arc.next)
arc.next = arc.next.prev
arc = arc.next
edge = Edge(intersection_point)
self.voronoi.append(edge)
arc.prev.lower_edge = arc.upper_edge = edge
edge = Edge(intersection_point)
self.voronoi.append(edge)
arc.next.upper_edge = arc.lower_edge = edge
self.check_circle_event(arc)
self.check_circle_event(arc.prev)
self.check_circle_event(arc.next)
return True
arc = arc.next
return False
def check_circle_event(self, arc):
if arc.circle_event is not None and arc.circle_event.x != self.LEFT:
arc.circle_event.valid = False
arc.circle_event = None
if arc.prev is None or arc.next is None:
return
max_x, center = find_circle_center(arc.prev.point, arc.point,
arc.next.point)
if center is not None and max_x > self.LEFT:
arc.circle_event = Circle(max_x, center, arc)
self.events.push(arc.circle_event)
def finish_edges(self):
limit = self.RIGHT + (self.RIGHT - self.LEFT) + (self.BOTTOM -
self.TOP)
arc = self.beach_line
while arc.next is not None:
if arc.lower_edge is not None:
point = find_intersection_of_parabolas(arc.point,
arc.next.point,
limit * 2.0)
arc.lower_edge.finish(Point(-1 * point.x, -1 * point.y))
arc = arc.next
def finish_edges_with_visualization(self):
limit = self.RIGHT + (self.RIGHT - self.LEFT) + (self.BOTTOM -
self.TOP)
arc = self.beach_line
while arc.next is not None:
if arc.lower_edge is not None:
point = find_intersection_of_parabolas(arc.point,
arc.next.point,
limit * 2.0)
arc.lower_edge.finish(Point(-1 * point.x, -1 * point.y))
self.scenes.append(
Scene([
PointsCollection(self.points, color='red'),
PointsCollection(self.get_voronoi_points(),
color='blue')
], [LinesCollection(self.get_voronoi_lines())]))
arc = arc.next
def print_output(self):
for edge in self.voronoi:
if edge.done:
print(edge.start.x, edge.start.y, edge.end.x, edge.end.y)
else:
print(edge.start.x, edge.start.y)
def get_voronoi_points(self):
result = []
for edge in self.voronoi:
if edge.done:
result.append((edge.start.x, edge.start.y))
result.append((edge.end.x, edge.end.y))
else:
result.append((edge.start.x, edge.start.y))
return result
def get_voronoi_lines(self):
result = []
for edge in self.voronoi:
if edge.done:
result.append([(edge.start.x, edge.start.y),
(edge.end.x, edge.end.y)])
return result