…the values for X, Y and Z within the “Quaternion Rotations” define a “Rotation Axis” and W a “Rotation Angle” around that axis
This is not correct! The rotation angle is ‘hidden’ in all 4 variables W, X, Y and Z.
If the vector for the axis of rotation is (x, y, z), then:
W = cos(angle/2)
X = x*sin(angle/2)
Y = y*sin(angle/2)
Z = z*sin(angle/2).
It should be clear from this that you cannot change only one variable without affecting at least one of the other three…
You could say that a quaternion is a 4 dimensional vector of length 1!
Somebody should actually explain quaternions in a clear and understandable way here 😉
