def test_distance(self):
q = Quaternion(scalar=0, vector=[1,0,0])
p = Quaternion(scalar=0, vector=[0,1,0])
self.assertEqual(pi/2, Quaternion.distance(q,p))
q = Quaternion(angle=pi/2, axis=[1,0,0])
p = Quaternion(angle=pi/2, axis=[0,1,0])
self.assertEqual(pi/3, Quaternion.distance(q,p))
q = Quaternion(scalar=1, vector=[1,1,1])
p = Quaternion(scalar=-1, vector=[-1,-1,-1])
p._normalise()
q._normalise()
self.assertAlmostEqual(0, Quaternion.distance(q,p), places=8)
def rpy_to_quaternion(rpy):
# based on wikipedia: https://en.wikipedia.org/wiki/Conversion_between_quaternions_and_Euler_angles
roll = rpy[0]
pitch = rpy[1]
yaw = rpy[2]
cy = math.cos(yaw * 0.5)
sy = math.sin(yaw * 0.5)
cr = math.cos(roll * 0.5)
sr = math.sin(roll * 0.5)
cp = math.cos(pitch * 0.5)
sp = math.sin(pitch * 0.5)
w = cy * cr * cp + sy * sr * sp
x = cy * sr * cp - sy * cr * sp
y = cy * cr * sp + sy * sr * cp
z = sy * cr * cp - cy * sr * sp
quat = Quaternion(w, x, y, z)
quat._normalise()
return quat
