ScrollRect scroll to a gameObject position ?

Unity Engine
1

Hello,

I would like to know how to move my scroll rect vertically to another gameobject. Here is an example :

I have already tried to move it with values but i need to be on the exact position of my gameobject (vertically)

IEnumerator GoTo(float a_destValue)
{
float startValue = myScrollRect.verticalNormalizedPosition;
float percent = 0f;
while (percent <= 1f)
{
myScrollRect.verticalNormalizedPosition = Mathf.Lerp(startValue, a_destValue, Mathf.Clamp01(percent));
percent += Time.deltaTime;
yield;
}
}

Someone have an idea ?
Thank you !

2

Use CenterOnItem(RectTransform [target](http://unity3d.com/support/documentation/ScriptReference/30_search.html?q=target))to focus your object.

using UnityEngine;
using UnityEngine.UI;

[RequireComponent(typeof(ScrollRect))]
public class ScrollRectEnsureVisible : MonoBehaviour
{
    public RectTransform maskTransform;

    private ScrollRect mScrollRect;
    private RectTransform mScrollTransform;
    private RectTransform mContent;

    public void CenterOnItem(RectTransform target)
    {
        // Item is here
        var itemCenterPositionInScroll = GetWorldPointInWidget(mScrollTransform, GetWidgetWorldPoint(target));
        // But must be here
        var targetPositionInScroll = GetWorldPointInWidget(mScrollTransform, GetWidgetWorldPoint(maskTransform));
        // So it has to move this distance
        var difference = targetPositionInScroll - itemCenterPositionInScroll;
        difference.z = 0f;

        //clear axis data that is not enabled in the scrollrect
        if (!mScrollRect.horizontal)
        {
            difference.x = 0f;
        }
        if (!mScrollRect.vertical)
        {
            difference.y = 0f;
        }

        var normalizedDifference = new Vector2(
            difference.x / (mContent.rect.size.x - mScrollTransform.rect.size.x),
            difference.y / (mContent.rect.size.y - mScrollTransform.rect.size.y));

        var newNormalizedPosition = mScrollRect.normalizedPosition - normalizedDifference;
        if (mScrollRect.movementType != ScrollRect.MovementType.Unrestricted)
        {
            newNormalizedPosition.x = Mathf.Clamp01(newNormalizedPosition.x);
            newNormalizedPosition.y = Mathf.Clamp01(newNormalizedPosition.y);
        }

        mScrollRect.normalizedPosition = newNormalizedPosition;
    }
    private void Awake()
    {
        mScrollRect = GetComponent<ScrollRect>();
        mScrollTransform = mScrollRect.transform as RectTransform;
        mContent = mScrollRect.content;
        Reset();
    }
    private void Reset()
    {
        if (maskTransform == null)
        {
            var mask = GetComponentInChildren<Mask>(true);
            if (mask)
            {
                maskTransform = mask.rectTransform;
            }
            if (maskTransform == null)
            {
                var mask2D = GetComponentInChildren<RectMask2D>(true);
                if (mask2D)
                {
                    maskTransform = mask2D.rectTransform;
                }
            }
        }
    }
    private Vector3 GetWidgetWorldPoint(RectTransform target)
    {
        //pivot position + item size has to be included
        var pivotOffset = new Vector3(
            (0.5f - target.pivot.x) * target.rect.size.x,
            (0.5f - target.pivot.y) * target.rect.size.y,
            0f);
        var localPosition = target.localPosition + pivotOffset;
        return target.parent.TransformPoint(localPosition);
    }
    private Vector3 GetWorldPointInWidget(RectTransform target, Vector3 worldPoint)
    {
        return target.InverseTransformPoint(worldPoint);
    }
}
21 Likes
3

Thank you jschiek ! :slight_smile:

4

It doesn’t work when length of content less than length of scrollrect (viewport) itself.

5

Scrolling to content that fits entirely inside the viewport is ill defined, and you’ll see that e.g. your web browser makes a UX choice totally different than yours. Nonetheless, you can “center” on something by using “slack” child rectangles of height like Mathf.max(2*viewportSize.y - contentSize.y, 0) or Mathf.max(viewportSize.y - contentSize.y, 0).

6

jschiek thank you :wink:

7

Thank you jschiek it helped me a lot