Face forward direction of movement

Question

I am trying to get an object like an arrow to point in the direction it is moving. I am using this code from the Roll a Ball tutorial. Any ideas?

public var force:float = 1.0; public var simulateAccelerometer:boolean = false;

function Start()
{

 iPhoneSettings.screenOrientation = iPhoneScreenOrientation.Landscape;

function FixedUpdate () {
    var dir : Vector3 = Vector3.zero;

 if (simulateAccelerometer)
 {

     dir.x = Input.GetAxis("Horizontal");
     dir.z = Input.GetAxis("Vertical");
 }
 else
 {

     dir.x = -iPhoneInput.acceleration.y;
     dir.z = iPhoneInput.acceleration.x;


     if (dir.sqrMagnitude &gt; 1)
         dir.Normalize();
 }

 rigidbody.AddForce(dir * force);

Thanks

Answer 1

Best Answer

Answer by runevision · Feb 09, 2011 at 12:09 PM

Use this:

transform.rotation = Quaternion.LookRotation(dir);

Note that if you make the object always face in the direction of movement this way, it won't be rolling anymore (of course) so that may affect the physics if you were relying on a rolling behaviour.

You could instead still have a round collider that is rolling, and have your visible object be a child object of that, and use the LookRotation function on that child, so the visible child (without a collider) is pointing in the direction of movement while the invisible parent (with a collider) is rolling freely.

Edit: Actually, you may want to use this to avoid very fast rotations, or errors if the object is standing still:

if (dir != Vector3.zero) {
    transform.rotation = Quaternion.Slerp(
        transform.rotation,
        Quaternion.LookRotation(dir),
        Time.deltaTime * rotationSpeed
    );
}

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Richard 3 · Feb 09, 2011 at 02:04 PM 0

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This is exactly what I needed. Thanks

pikpiak · Jul 18, 2011 at 06:30 AM 0

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Is there anyway to maintain it's last faced direction even after no Input?

Answer 2

Answer by Stardog · Jan 20, 2013 at 09:48 AM

Here's another solution that will look in the direction the ball's moving, not the direction of input. Good for attaching a hat/gun to the ball or something.

 transform.position = ballGameObject.transform.position;
 transform.LookAt(transform.position + ballGameObject.rigidbody.velocity);

Position this object to where the ball is.
Add the ball's "rigidbody.velocity" to this object's position, and then look at it. (The velocity value gives a point offset from the center that you can look at.)

Now just make your arrow model a child of this GameObject. Move the Z position out as far as you want the arrow to appear.

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shough · Apr 05, 2018 at 03:28 AM 0

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Great solution! Works perfect for hats

Answer 3

Answer by joeyzhao2018 · Nov 15, 2021 at 02:19 AM

In my case I'm working on a top-down 2D game and I need to rotate my bullet. The code is

 transform.rotation = Quaternion.LookRotation(Vector3.forward, shootDirection);

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Face forward direction of movement

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