组件源码

using UnityEngine;

using System.Collections;

//This script allows to drag rigidbody2D elements on the scene with orthographic camera

//Attach this script to your camera

public class DragRigidbody2D : MonoBehaviour

{

    public float Damper = 5f;

    public float Frequency = 3;

    public float Drag = 10f;

    public float AngularDrag = 5f;

    private SpringJoint2D _springJoint;

    private Camera _camera;

    private RaycastHit2D _rayHit;

        void Start ()

        {

        _camera = gameObject.GetComponent<Camera>();

        }

        void Update ()

    {

        if (!Input.GetMouseButtonDown(0))

            return;

        //Looking for any collider2D under mouse position

        _rayHit = Physics2D.Raycast(Camera.main.ScreenToWorldPoint(Input.mousePosition), Vector2.zero);

        if (_rayHit.collider == null)

            return;

        if (!_rayHit.collider.rigidbody2D || _rayHit.collider.rigidbody2D.isKinematic)

            return;

        if (!_springJoint)

        {

            //Create spring joint

            GameObject go = new GameObject("[Rigidbody2D_dragger]");

            Rigidbody2D body = go.AddComponent<Rigidbody2D>();

            _springJoint = go.AddComponent<SpringJoint2D>();

            body.isKinematic = true;

        }

            _springJoint.transform.position = _rayHit.point;

            _springJoint.anchor = Vector2.zero;

        //Apply parameters to spring joint

            _springJoint.frequency = Frequency;

            _springJoint.dampingRatio = Damper;

            _springJoint.distance = 0;

            _springJoint.connectedBody = _rayHit.collider.rigidbody2D;

            StartCoroutine("DragObject");

        }

    IEnumerator DragObject()

    {

        var oldDrag = _springJoint.connectedBody.drag;

        var oldAngDrag = _springJoint.connectedBody.angularDrag;

        _springJoint.connectedBody.drag = Drag;

        _springJoint.connectedBody.angularDrag = AngularDrag;

        while (Input.GetMouseButton(0))

        {

            Vector2 newPos = _camera.ScreenToWorldPoint(Input.mousePosition);

            _springJoint.transform.position = new Vector2(newPos.x, newPos.y);

            yield return new WaitForSeconds(0.1f);

        }

        if (_springJoint.connectedBody)

        {

            _springJoint.connectedBody.drag = oldDrag;

            _springJoint.connectedBody.angularDrag = oldAngDrag;

            _springJoint.connectedBody = null;

        }

    }

}

使用方法

Drag预览