def test_vector():
for _ in xrange(1000):
v = random_vector()
x, y = v
assert v + (2, 0) == Vector(x+2, y)
assert v - (2, 0) == Vector(x-2, y)
assert +v == Vector(x, y)
assert -v == Vector(-x, -y)
assert v * 2 == Vector(2*x, 2*y)
assert v / 2 == Vector(x/2, y/2)
v = Vector(1, 0)
assert v.angle == 0
v.angle = pi/2
v.x, v.y = map(Approx, v)
assert v == Vector(0, 1)
v.length = 2
v.x, v.y = map(Approx, v)
assert v == Vector(0, 2)
v.move(2, 2)
assert v == Vector(2, 4)
v.scale(2, 2, pivot=(1, 1))
assert v == Vector(3, 7)
v.rotate(pi/2, pivot=(3, 3))
v.x, v.y = [Approx(n) for n in v]
assert v == Vector(-1, 3)
class Circle(Shape):
def __init__(self, center=(0, 0), radius=1.0):
self.center = Vector(*center)
self.radius = radius
def __info__(self):
return "c=%s, r=%s" % (self.center, self.radius)
# --------------------------------------------------------------------------
# Geometry interface
def move(self, dx=0.0, dy=0.0):
if dx == 0.0 and dy == 0.0:
return
self.center.move(dx, dy)
def scale(self, factor, pivot=None):
if factor == 1.0:
return
if pivot is not None:
self.center.scale(factor, pivot)
self.radius *= factor
def rotate(self, alpha, pivot=None):
if alpha == 0.0:
return
if pivot is not None:
self.center.rotate(alpha, pivot)
# --------------------------------------------------------------------------
# Shape interface
def contains_point(self, point):
radius = self.radius
delta = point - self.center
return delta.squared_length <= radius * radius
def segment_intersections(self, segment):
points = []
cx, cy = self.center
r = self.radius
m = segment.slope
if m is None: # vertical segment
if cx - r <= segment.a.x <= cx + r:
pass
else:
b = segment.y_at(0.0)
A = 1 + m*m
B = -2*cx + 2*m*b -2*m*cy
C = cx*cx + cy*cy + b*b - r*r - 2*b*cy
x0, x1 = solve_quadratic(A, B, C)
xinterval = segment.xrange
if x0 in xinterval:
points.append(Vector(x0, segment.y_at(x0)))
if x1 in xinterval:
points.append(Vector(x1, segment.y_at(x1)))
return points
