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import vec2, math
def intersectLineCircle((p, no), (C, r)):
x = vec2.sub(p,C)
b = 2.*vec2.dot(no, x)
c = vec2.sqr(x) - r*r
dist = b*b - 4*c
if dist<0:
return None
else:
d = math.sqrt(dist)
t0 = (-b - d)*.5
t1 = (-b + d)*.5
return (t0,t1)
#def intersectLineCircle((lineP,lineN),(circleP,circleR)):
# dx,dy = vec2.sub(lineP,circleP)
# nx,ny = lineN
#
# a = (nx*nx + ny*ny)
# b = 2*(dx*nx + dy*ny)
# c = (dx*dx + dy*dy) - circleR*circleR
#
# k = b*b - 4*a*c
# if k<0:
# return None
# else:
# d = math.sqrt(k)
# t1 = (-b - d)/2*a
# t0 = (-b + d)/2*a
# return t0,t1
def intersectCircleCircle(c0P, c0R, c1P, c1R):
v = vec2.sub(c1P, c0P)
d = vec2.length(v)
R = c0R
r = c1R
try:
x = (d*d - r*r + R*R)/(2*d)
except ZeroDivisionError:
if R<r:
return 'inside',()
elif r>R:
return 'outside',()
else:
return 'coincident',()
k = R*R - x*x
if k<0:
if x<0:
return 'inside',()
else:
return 'outside',()
else:
y = math.sqrt(k)
return 'intersect',(vec2.toangle(v),vec2.toangle((x,y)))
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