CODEWITHSUNDEEP
objectunity-game-enginesmoothing
Johnny
Johnny

Reputation: 612

Slow down object?

I have a Sphere Object falling down from the top of the screen (Sphere position y = 5). And I have a Cube with "isTrigger = true" and "Mesh renderer = false" and the position with "y = 0.5" (0.5 = center of the cube). You can't see the cube.

The Sphere is now falling. Now I want, when the sphere touches the cube, that the sphere is slowing down to zero (without reverse). I want a attenuation/damping.

I tried this example without success: http://docs.unity3d.com/Documentation/ScriptReference/Vector3.SmoothDamp.html

// target = sphere object 
public Transform target;

public float smoothTime = 0.3F;
private Vector3 velocity = Vector3.zero;
private bool slowDown = false;


void Update () {
if (slowDown) {
    Vector3 targetPosition = target.TransformPoint(new Vector3(0, 0, 0));
            transform.position = Vector3.SmoothDamp(transform.position, targetPosition, ref velocity, smoothTime);
}   

}



void OnTriggerEnter(Collider other) {
if (other.name == "Sphere") {
    slowDown = true;
}
}

The script is attached to the cube.

Upvotes: 0

Views: 3649

Answers (1)

Shironecko
Shironecko

Reputation: 36

You may want to try this approach:

// We will multiply our sphere velocity by this number with each frame, thus dumping it
public float dampingFactor = 0.98f;
// After our velocity will reach this threshold, we will simply set it to zero and stop damping
public float dampingThreshold = 0.1f;

void OnTriggerEnter(Collider other)
{
    if (other.name == "Sphere")
    {
        // Transfer rigidbody of the sphere to the damping coroutine
        StartCoroutine(DampVelocity(other.rigidbody));
    }
}

IEnumerator DampVelocity(Rigidbody target)
{
    // Disable gravity for the sphere, so it will no longer be accelerated towards the earth, but will retain it's momentum
    target.useGravity = false;

    do
    {
        // Here we are damping (simply multiplying) velocity of the sphere whith each frame, until it reaches our threshold 
        target.velocity *= dampingFactor;
        yield return new WaitForEndOfFrame();
    } while (target.velocity.magnitude > dampingThreshold);

    // Completely stop sphere's momentum
    target.velocity = Vector3.zero;
}

I am assuming here that your have a Rigidbody atached to your sphere and it's falling to the 'natural' gravity (if not - simply add Rigidbody component to your sphere, no further tweaking required) and you are familiar with coroutines, if not - take a look at this manual: http://docs.unity3d.com/Documentation/Manual/Coroutines.html

Coroutines can be quite helpful, when used wisely :)

Upvotes: 2

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