在 Unity 2D 中拖动对象

我正在寻找 Unity 2D 的对象拖动脚本。我在网上找到了一个很好的方法，但它似乎只能在Unity 3D中工作。这对我来说不好，因为我正在制作 2D 游戏，而且它不会以这种方式与“墙”发生碰撞。

我尝试将其重写为 2D，但使用向量时遇到了错误。

如果您能帮我将其重写为 2D，我将非常高兴。

以下是在 3D 中运行的代码：

using UnityEngine;
using System.Collections;

[RequireComponent(typeof(BoxCollider))]

public class Drag : MonoBehaviour {
    private Vector3 screenPoint;
    private Vector3 offset;

void OnMouseDown() {

    offset = gameObject.transform.position - Camera.main.ScreenToWorldPoint(new Vector3(Input.mousePosition.x, Input.mousePosition.y, screenPoint.z));
}

void OnMouseDrag()
{
    Vector3 curScreenPoint = new Vector3(Input.mousePosition.x, Input.mousePosition.y, screenPoint.z);
    Vector3 curPosition = Camera.main.ScreenToWorldPoint(curScreenPoint) + offset;
    transform.position = curPosition;
}
}

对于使用此代码时遇到问题的人，我使用 ScreenPointToRay 来使用代数光线投射（快速）来确定对象应距离相机多远。这适用于正交相机和透视相机

此外，该对象可以使用Collider能够被拖来拖去。所以没有必要使用[RequireComponent(typeof(BoxCollider2D))].

对我来说效果很好的最终代码是：

using UnityEngine;
using System.Collections;

public class DragDrop : MonoBehaviour {
    // The plane the object is currently being dragged on
    private Plane dragPlane;

    // The difference between where the mouse is on the drag plane and 
    // where the origin of the object is on the drag plane
    private Vector3 offset;

    private Camera myMainCamera; 

    void Start()
    {
        myMainCamera = Camera.main; // Camera.main is expensive ; cache it here
    }

    void OnMouseDown()
    {
        dragPlane = new Plane(myMainCamera.transform.forward, transform.position); 
        Ray camRay = myMainCamera.ScreenPointToRay(Input.mousePosition); 

        float planeDist;
        dragPlane.Raycast(camRay, out planeDist); 
        offset = transform.position - camRay.GetPoint(planeDist);
    }

    void OnMouseDrag()
    {   
        Ray camRay = myMainCamera.ScreenPointToRay(Input.mousePosition); 

        float planeDist;
        dragPlane.Raycast(camRay, out planeDist);
        transform.position = camRay.GetPoint(planeDist) + offset;
    }
}