Unity实现引导页效果

using system.collections;
using system.collections.generic;
using unityengine;
using unityengine.eventsystems;
using dg.tweening;
using unityengine.ui;

public class asd : monobehaviour,ibegindraghandler, idraghandler,ienddraghandler
{
  /// <summary>
  /// 可移动的最大最小x轴坐标
  /// </summary>
  private float minx, maxx;
  /// <summary>
  /// 开始触摸时，算出偏移值，防止跳变
  /// </summary>
  private float offsetx;

  /// <summary>
  /// 灵敏度
  /// </summary>
  private float sensitivityx;
  /// <summary>
  /// 当前显示第几页
  /// </summary>
  private int currentshowindex = 1;

  private void start()
  {
    (transform as recttransform).pivot = new vector2(0, 0.5f);
    debug.log(screen.width + "  " + screen.height);
    for (int i = 0; i < transform.childcount; i++)
    {
      (transform.getchild(i) as recttransform).sizedelta = new vector2(0, 0);
      //canvas的rendermode要设置成overlay形式
      //这里i*1080是因为canvas的uiscalemode设置成了scalewithscreensize，resolution为x=1080,y=1920
      //如果canvas的uiscalemode设置成constantpixelsize则吧这里的i*1080改成i*screen.width
      (transform.getchild(i) as recttransform).anchoredposition = new vector2(i * 1080.0f, 0);
    }

    minx = -((transform.childcount - 1) * screen.width);
    maxx = 0.0f;
    //如果移动超过页面的五分之一，则切换页面
    sensitivityx = screen.width / 5;
  }

  public void onbegindrag(pointereventdata eventdata)
  {
    offsetx = transform.position.x - input.mouseposition.x;
  }

  public void ondrag(pointereventdata eventdata)
  {
    //将物体坐标限制在最大最小x轴坐标内
    transform.position = new vector2(input.mouseposition.x + offsetx, transform.position.y);
    if (transform.position.x <= minx)
    {
      transform.position = new vector2(minx, transform.position.y);
    }
    else if (transform.position.x >= maxx)
    {
      transform.position = new vector2(maxx, transform.position.y);
    }
  }

  public void onenddrag(pointereventdata eventdata)
  {
    //判断坐标，是否需要切换页面
    if (transform.position.x > getleftx())
    {
      currentshowindex--;
    }
    else if (transform.position.x < getrightx())
    {
      currentshowindex++;
    }
    transform.domovex(-(currentshowindex - 1) * screen.width, 0.2f);
  }

  float getleftx() {
    return -((currentshowindex - 1) * screen.width - sensitivityx);
  }

  float getrightx() {
    return -((currentshowindex - 1) * screen.width + sensitivityx);
  }
}