Pinch in order to Scale an object

Unity Engine
1

I am working on application for iOS, and I want the user to be able to scale the item to be larger or smaller using two fingers pinching and spreading, but I cannot get it figured out.

Here is my script:

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class PinchZoom : MonoBehaviour
{
    public Touch touch0;
    public Touch touch1;

    private float distance;

    private float newDistance0;
    private float newDistance1;

    private float newDistance;

    public float scaleSpeed;

    public float scaleValue;

    private Vector2 midpoint;

    private bool firstRun;

    private void Start()
    {
        distance = 1;
        newDistance = 1;
    }

    // Update is called once per frame
    void Update()
    {
        if (Input.touchCount == 2 && Input.GetTouch(0).phase == TouchPhase.Began)
        {
            touch0 = Input.GetTouch(0);
            touch1 = Input.GetTouch(1);

            midpoint = (touch0.position + touch1.position) / 2;

            distance = Vector2.Distance(midpoint, (touch0.position + touch1.position) / 2);
        }
        if (Input.touchCount == 2)
        {

            touch0 = Input.GetTouch(0);
            touch1 = Input.GetTouch(1);

            if (Input.GetTouch(0).phase == TouchPhase.Began)
            {
                Debug.Log("I Begin!!!!!!!!!!!!");
                firstRun = false;
                distance = Vector2.Distance(midpoint, (touch0.position + touch1.position) / 2);
            }

            if (touch0.phase == TouchPhase.Moved && touch1.phase == TouchPhase.Moved)
            {
                if (firstRun)
                {
                    distance = newDistance;
                }
                firstRun = true;

                midpoint = (touch0.position + touch1.position) / 2;
                newDistance0 = Vector2.Distance(midpoint, touch0.position);
                newDistance1 = Vector2.Distance(midpoint, touch1.position);
                newDistance = (newDistance0 + newDistance1) / 2;
            }

            Debug.Log("Distance = " + distance);
            Debug.Log("New Distance = " + newDistance);
            Debug.Log("Subtracted together they eagual = " + (distance - newDistance));

            scaleValue = (scaleSpeed * (newDistance - distance));  //Must move on slope scaleSpeed *   + 0.1f

            //Debug.Log(scaleValue);
            //Debug.Log(gameObject.transform.localScale);

            if ((gameObject.transform.localScale.x > 10 && scaleValue < 0) || (gameObject.transform.localScale.x < 0.1f && scaleValue > 0) || (gameObject.transform.localScale.x < 10000 && gameObject.transform.localScale.x > 0.1f))
            {
                gameObject.transform.localScale += new Vector3(scaleValue, scaleValue, scaleValue);
            }
        }
    }
}

Currently it somewhat works, but whenever the user tries to scale the object down, it first makes it much larger, then begins scaling it down. Does anybody know what I am doing wrong?

2

The scaling should be a multiplier for localScale, don’t add or subtract, only assign for example:

gameObject.transform.localScale = Vector3.one * pinchZoom;

Then pinchZoom should be by default 1. Then you add or subtract only from the pinchZoom value. 0 would be invisible and 2 would be large. This makes it deterministic instead of additive or lossy like your code is doing.

2 Likes
3

That worked. Thanks!