abs(x)<=a/2 and abs(y)<=b/2 and abs(x)>=c/2 or abs(y)>=d/2
(-a/2, -b/2) | (a/2, -b/2) | (a/2, b/2) | (-a/2, b/2) | (-c/2, -d/2) | (c/2, -d/2) | (c/2, d/2) | (-c/2, d/2)
8
0 A = a b - c d x^_ = (0, 0)
J_x invisible comma x = 1/12 (a b^3 - c d^3)
J_y invisible comma y = 1/12 (a^3 b - c^3 d)
J_zz = 1/12 (a^3 b + a b^3 - c d (c^2 + d^2))
J_x invisible comma y = 0
r_x = 1/2 sqrt((a b^3 - c d^3)/(3 a b - 3 c d)) r_y = 1/2 sqrt((a^3 b - c^3 d)/(3 a b - 3 c d))
a | b | a | b | c | d | c | d
p = 2 (a + b + c + d)
sqrt(a^2 + b^2)
