Решено.
mult = lambda a, b: a.x * b.x + a.y * b.y
class Point(object):
def __init__(self, x, y):
self.x = float(x)
self.y = float(y)
class Line(object):
def __init__(self, begin, end):
self.begin = begin
self.end = end
@property
def direction(self):
return Point(self.end.x - self.begin.x, self.end.y - self.begin.y)
@property
def normal(self):
return Point(self.end.y - self.begin.y, self.begin.x - self.end.x)
class Polygon(object):
def __init__(self, points):
self.count = len(points)
self.edges = []
for i in xrange(self.count-1):
self.edges.append(Line(points[i], points[i+1]))
self.edges.append(Line(points[-1], points[0]))
# Реализаця алгоритма!
def cyruse_beck(self, l):
t_begin = 0.0
t_end = 1.0
dirL = l.direction
for edge in self.edges:
dir_edg = edge.direction
Q = Point(l.begin.x - dir_edg.x, l.begin.y - dir_edg.y)
N = edge.normal
Pn = mult(dirL, N)
Qn = mult(Q, N)
if Pn == 0:
pass
else:
t = -Qn / Pn
if Pn > 0:
if t < t_begin:
return False
t_end = min(t_end, t)
else:
if t > t_end:
return False
t_begin = max(t_begin, t)
if t_end > t_begin:
if t_begin > 0:
l.begin = Point(l.begin.x + t_begin * dirL.x, l.begin.y + t_begin * dirL.y)
if t_end < 1:
l.end = Point(l.begin.x + t_end * dirL.x, l.begin.y + t_end * dirL.y)
else:
return False
return True