How to apply a one-time (initial) impulse force

Unity Engine
1

I know how to use the GetComponent<Rigidbody>().AddForce(); function. But to apply a one-time initial impulse, do I put this line in void start() or void update() ?

2

I’d try something like this:

public Vector3 impulse = new Vector3(5.0f, 0.0f, 0.0f);

bool m_oneTime = false;

void FixedUpdate ()
    {
    if (!m_oneTime)
        {
        GetComponent<Rigidbody>().AddForce(impulse, ForceMode.Impulse);
        m_oneTime = false;
        }
    }

Remember that the impuse is velocity multiplied by mass. If you want to give the object an initial velocity regardless it mass, use ForceMode.VelocityChange as second parameter to AddForce.

3

Just some minor fixes to the above code.

public class ImpulseForce : MonoBehaviour {
//Give it a momentary force of 5 in the X direction but you can change this in unity to apply
//an impulse force in any direction.
public Vector3 impulseMagnitude = new Vector3(5.0f, 0.0f, 0.0f);

bool m_oneTime = true;

// Use this for initialization
void Start () {

}

// Update is called once per frame
void FixedUpdate()
{
if (m_oneTime)
{
GetComponent().AddForce(impulseMagnitude, ForceMode.Impulse);
m_oneTime = false;
Debug.Log(“Here”);
}
}
}

4

Oh! Dumb mistake, thanks! I’m editing the original post.