如何显示换档。

Question

我正在开发一个统一的赛车游戏，我写了以下JAVASCRIPT代码来移动汽车。我能够使用我的逻辑显示汽车的速度，但不能显示换档。所以帮我纠正一下。齿轮变量仅在文本区域中显示“0”。但是在检查条件后没有增加一个。

if(Input.GetKeyDown("right")) {
                   transform.Rotate(0, 1, 0);
                }
                 if(Input.GetKeyDown("left")) {
                   transform.Rotate(0, -1, 0);
                }
     switch(currentMode) {
             case ShipModes.Idle:
                if(Input.GetKeyDown(KeyCode.W)) { 
                   currentMode = ShipModes.Moving;
                }
                if(Input.GetKeyDown(KeyCode.S)) {
                    currentMode = ShipModes.Reverse;
                }
                break;
             case ShipModes.Moving:
                if(Input.GetKeyDown(KeyCode.S)) {
                   currentMode = ShipModes.Idle;
                }

                break;
              case ShipModes.Reverse:
                 if(!Input.GetKey(KeyCode.S)) {
                    currentMode = ShipModes.Idle;
                 }
                 break;
       }
       //Movement phase 
       switch(currentMode) {
             case ShipModes.Idle:
                 currentSpeed = Mathf.Lerp(currentSpeed, 0, Time.deltaTime);
                   break;
             case ShipModes.Moving:
                 currentSpeed = Mathf.Lerp(currentSpeed, maxSpeed, Time.deltaTime); //Or MoveTowards
                 break;
             case ShipModes.Reverse:
                 currentSpeed = Mathf.Lerp(currentSpeed, maxReverseSpeed, Time.deltaTime); //Or MoveTowards
                 break;
       }
       //Actually move


        score.text="SPEED "+Mathf.Abs(currentSpeed).ToString("F0");

        //Gear change display starts from here
        var gr=0;
        var sp=currentSpeed;
        while(gr!=5)
        {
            transform.position += transform.forward * currentSpeed * Time.deltaTime;
            if(currentSpeed>=sp)
            {
                gear.text="GEAR "+gr;
            }
            sp=sp+5;
            gr=gr+1;
        }