unity双指放大缩小图片

在Unity中，可以使用Touch类来检测多点触控事件。要实现双指缩放图片，可以使用两个触摸点的位置和距离来计算缩放比例。以下是一个简单的示例代码：

using UnityEngine;

public class PinchZoom : MonoBehaviour
{
    public float zoomSpeed = 0.5f;
    public float minZoom = 0.5f;
    public float maxZoom = 2.0f;

    private Vector2 previousTouchPosition1;
    private Vector2 previousTouchPosition2;

    void Update()
    {
        if (Input.touchCount == 2)
        {
            // Get the two touch positions
            Touch touch1 = Input.GetTouch(0);
            Touch touch2 = Input.GetTouch(1);

            // Calculate the touch delta
            Vector2 touchDelta1 = touch1.position - previousTouchPosition1;
            Vector2 touchDelta2 = touch2.position - previousTouchPosition2;
            float touchDeltaMagnitude = (touchDelta1 + touchDelta2).magnitude;

            // Calculate the zoom amount
            float zoomAmount = touchDeltaMagnitude * zoomSpeed * Time.deltaTime;

            // Update the camera's orthographic size
            Camera.main.orthographicSize = Mathf.Clamp(Camera.main.orthographicSize - zoomAmount, minZoom, maxZoom);

            // Save the touch positions for the next frame
            previousTouchPosition1 = touch1.position;
            previousTouchPosition2 = touch2.position;
        }
        else
        {
            // Reset the touch positions
            previousTouchPosition1 = Vector2.zero;
            previousTouchPosition2 = Vector2.zero;
        }
    }
}

在这个示例中，我们使用Camera的orthographicSize属性来实现缩放。通过计算两个触摸点的位置和距离，我们可以计算出缩放量，并将其应用于相机的orthographicSize。我们还可以使用minZoom和maxZoom变量来限制缩放范围，确保不会超出指定的范围。