Scale GameObject over time

Question

I made a test game in unity that makes it so when I click on a button, it spawns a cylinder created from a factory class. I'm trying to make it so when I create the cylinder, its height shrinks over the next 20 seconds. Some methods I found are difficult to translate into what I'm doing. If you could lead me to the right direction, I'd very much appreciate it.

Here's my code for the cylinder class

 public class Cylinder : Shape
{
    public Cylinder()
    {
    GameObject cylinder = GameObject.CreatePrimitive(PrimitiveType.Cylinder);
        cylinder.transform.position = new Vector3(3, 0, 0);
        cylinder.transform.localScale = new Vector3(1.0f, Random.Range(1, 2)-1*Time.deltaTime, 1.0f);

        cylinder.GetComponent<MeshRenderer>().material.color = Random.ColorHSV();
        Destroy(cylinder, 30.0f);
    }
}

Programmer · Answer 1 · 2017-10-06T09:14:45.397

This can be done with the Time.deltaTime and Vector3.Lerp in a coroutine function. Similar to Rotate GameObject over time and Move GameObject over time questions. Modified it a little bit to do just this.

bool isScaling = false;

IEnumerator scaleOverTime(Transform objectToScale, Vector3 toScale, float duration)
{
    //Make sure there is only one instance of this function running
    if (isScaling)
    {
        yield break; ///exit if this is still running
    }
    isScaling = true;

    float counter = 0;

    //Get the current scale of the object to be moved
    Vector3 startScaleSize = objectToScale.localScale;

    while (counter < duration)
    {
        counter += Time.deltaTime;
        objectToScale.localScale = Vector3.Lerp(startScaleSize, toScale, counter / duration);
        yield return null;
    }

    isScaling = false;
}

USAGE:

Will scale GameObject within 20 seconds:

StartCoroutine(scaleOverTime(cylinder.transform, new Vector3(0, 0, 90), 20f));

`Vector3 startScaleSize = objectToScale.position;` Should be `Vector3 startScaleSize = objectToScale.localScale;` — TheSkimek, Oct 06 '17 at 09:11
@TheSkimek Yup, that's right. This was a quick port. Thanks for the correction. — Programmer, Oct 06 '17 at 09:15

score 1 · Answer 2 · answered Oct 05 '17 at 13:46

1

Check out Lerp. A general example of how to use it would be something like this:

float t = 0;
Update()
{
    t += Time.deltaTime;
    cylinder.localScale = new Vector3(1, Mathf.Lerp(2f, 1f, t/3f), 1); // shrink from 2 to 1 over 3 seconds;
}

answered Oct 05 '17 at 13:46

ryeMoss

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Sergiy Klimkov · Answer 3 · 2017-10-05T14:27:30.373

You will create a new monobehaviour script and add it to your primitive. Then you wil use "Update" method of monobehaviour (or use coroutine) for change object over time.

Monobehaviour must be look like this:

public class ShrinkBehaviour : MonoBehaviour
{
    bool isNeedToShrink;
    Config currentConfig;

    float startTime;
    float totalDistance;

    public void StartShrink(Config config)
    {
        startTime = Time.time;
        currentConfig = config;
        totalDistance = Vector3.Distance(currentConfig.startSize, currentConfig.destinationSize);
        isNeedToShrink = true;
        transform.localScale = config.startSize;
    }

    private void Update()
    {
        if (isNeedToShrink)
        {
            var nextSize = GetNextSize(currentConfig);

            if (Vector3.Distance(nextSize, currentConfig.destinationSize) <= 0.05f)
            {
                isNeedToShrink = false;
                return;
            }

            transform.localScale = nextSize;
        }
    }

    Vector3 GetNextSize(Config config)
    {
        float timeCovered = (Time.time - startTime) / config.duration;
        var result = Vector3.Lerp(config.startSize, config.destinationSize, timeCovered);
        return result;
    }

    public struct Config
    {
        public float duration;
        public Vector3 startSize;
        public Vector3 destinationSize;
    }
}

For using this, you must do next:

public Cylinder()
{
    GameObject cylinder = GameObject.CreatePrimitive(PrimitiveType.Cylinder);
    var shrink = cylinder.AddComponent<ShrinkBehaviour>();
    shrink.StartShrink(new ShrinkBehaviour.Config() { startSize = Vector3.one * 10, destinationSize = Vector3.one * 1, duration = 20f });
    cylinder.transform.position = new Vector3(3, 0, 0);

    cylinder.GetComponent<MeshRenderer>().material.color = Random.ColorHSV();
    Destroy(cylinder, 30.0f);
}

You must remember, monobehaviour-script must be in separate file, and must have name similar to monobehaviour-class name. For example, ShrinkBehaviour.cs;

What if I just want to shrink the object height for 20 seconds? — Kenneth Dionisi, Oct 05 '17 at 14:14
you didn't declare a definition for speed, where did you get speed from? — Kenneth Dionisi, Oct 05 '17 at 14:25
I'm trying and its only taking a few seconds to shrink to its destination size. — Kenneth Dionisi, Oct 05 '17 at 14:36
Fix it already. You dont need frac. Try to copy one more time :) — Sergiy Klimkov, Oct 05 '17 at 14:37
Nice. One more thing. Is there a way to only shrink its height? — Kenneth Dionisi, Oct 05 '17 at 14:42
You wil edit the destinationSize in ShrinkBehaviour.Config. And choose size, that you need. For example, replace "destinationSize = Vector3.one * 1", to "destinationSize = New Vector3(10, 1, 10)". Or try to switch vector axises. — Sergiy Klimkov, Oct 05 '17 at 14:46
So ShrinkBehaviour.Config is a key to script behaviour. You can configurate duration, start and needed scale here. — Sergiy Klimkov, Oct 05 '17 at 14:52

Scale GameObject over time

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