[Math] Why is this possible ?

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Hello guys,

I am trying to do a Movement Controller which moves to player forward relative to its direction. When I have done some research on this topic, I noticed that this line of code would do the trick:

 Vector3 direction = transform.rotation * new Vector3(Input.GetAxis("Horizontal"),0,Input.GetAxis("Vertical"));

Why are we able to apply the rotation (Quaternion as datatype) to the Vector3 which stores the Input values.

The next thing I noticed: If we turn around the statement, so the Vector3 is instaniated first, the line of code will no longer work and throw and error.

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Answer by LK84 · Aug 31, 2016 at 07:36 PM

you are unknowingly using the Quaternion.operator* :

http://docs.unity3d.com/ScriptReference/Quaternion-operator_multiply.html

As you can see you can use the operator for

1) Quaternion*Quaternion (returns Quaternion)

2) Quaternion*Vector3 (returns Vector3 ---> Your case)

Everything else, like Vector3*Quaternion will throw an error

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[Math] Why is this possible ?

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