如何修复我的游戏跳跃？

Question

我想创建一个游戏，我可以通过磁贴移动播放器。我不知道如何让它跳跃以及​​如何使它平滑。 到目前为止，这是我的代码：

using UnityEngine;
using System.Collections;

public class PlayerScript : MonoBehaviour {

    /*
     * TILE BY TILE MOVEMENT
     * */

    private bool isMoving = false;
    private bool isJumping = false;
    private Vector3 targetPosition = new Vector3();
    private Vector3 prevPosition = new Vector3();
    public static bool canMove = true;
    private Rigidbody2D rb2D;

    void Start(){
        prevPosition = transform.position;
        rb2D = GetComponent<Rigidbody2D> ();
    }

    public void Move(string moveDirection){
        if (isMoving == false && canMove == true) {

            isMoving = true;

            switch (moveDirection.ToLower()) {
            case "left":
                prevPosition = transform.position;
                targetPosition = prevPosition + new Vector3(-2,0,0);
                targetPosition.x = Mathf.Round(targetPosition.x);
                break;
            case "right":
                prevPosition = transform.position;
                targetPosition = prevPosition + new Vector3(2,0,0);
                targetPosition.x = Mathf.Round(targetPosition.x);
                break;
            }
        }
    }

    public void CancelMove(){
        targetPosition = prevPosition;
        Debug.Log("Canceled move");
    }

    void Update(){

        if (isMoving == false) {
            //Checks if there is ground
            RaycastHit2D hit;
            hit = Physics2D.Raycast (transform.position, -Vector2.up, 1.2f, 1 << LayerMask.NameToLayer("Ground"));
            Debug.DrawRay (transform.position, -Vector2.up* 1.2f);

            RaycastHit2D hitSideRight;
            hitSideRight = Physics2D.Raycast (transform.position, Vector2.right, 1.2f, 1 << LayerMask.NameToLayer("Ground"));
            Debug.DrawRay (transform.position, Vector2.right* 1.2f);

            RaycastHit2D hitSideLeft;
            hitSideLeft = Physics2D.Raycast (transform.position, -Vector2.right, 1.2f, 1 << LayerMask.NameToLayer("Ground"));
            Debug.DrawRay (transform.position, -Vector2.right* 1.2f);

            if((hitSideLeft.collider != null && hitSideLeft.collider.tag != "Box") || (hitSideRight.collider != null && hitSideRight.collider.tag != "Box")){
                CancelMove();
                Debug.Log("Can't move");
            }

            if (hit.collider != null || hit.collider == null){

                if (Input.GetAxisRaw ("Horizontal") > 0 && hitSideRight.collider == null) {
                    Move ("right"); 
                }

                if (Input.GetAxisRaw ("Horizontal") < 0 && hitSideLeft.collider == null) {
                    Move ("left");
                }

                if(Input.GetKeyDown(KeyCode.Space)){
                    rb2D.AddForce(new Vector2(0,800));
                }

            }
        } else {
            if( transform.position.x != targetPosition.x )
            {
                // Move this object towards the target position
                transform.position = Vector3.MoveTowards(transform.position, targetPosition, Time.deltaTime * 5f);
            }
            else
            {
                isMoving = false;
            }
        }
    }
}

此脚本已附加到播放器。玩家有一个rigidbody2D和一个boxCollider2D：http://i.stack.imgur.com/sEV5b.jpg