如何在 Unity 2D 中旋转 object，然后在该方向旋转 go？

Question

I am new to unity and C# but am now making a small game where you are a jellyfish in the sea. I want to make it that you mainly control the player with the arrow keys to face in different directions. The code below is what I have now, I thought it would work, but it doesn't. Do I need to change something completely or is it just a small error by me? It is a 2D game.

    float  tpx = transform.position.x;
    float  tpy = transform.position.y;


    if (Input.GetKey("up")){
        if (face_up){
            transform.position = new Vector2 (tpx, tpy + speed/1000);
            animation.SetBool("swim", true);
        }

        if (face_right){
            transform.position = new Vector2 (tpx + speed/1000, tpy);
            animation.SetBool("swim", true);
        }

        if (face_down){
            transform.position = new Vector2 (tpx, tpy + speed/1000);
            animation.SetBool("swim", true);
        }

        if (face_left){
            transform.position = new Vector2 (tpx - speed/1000, tpy);
            animation.SetBool("swim", true);
        }
    }
    else{
        animation.SetBool("swim", false); gameObject.transform.position = new Vector2 (transform.position.x, transform.position.y - speed/10000);
    }


    if (Input.GetKey("left")){
        if (face_up){
            transform.eulerAngles = Vector3.forward * 90;
            face_up = false;
            face_right = false;
            face_down = false;
            face_left = true;
        }

        if (face_right){
            transform.eulerAngles = Vector3.forward * 0;
            face_up = true;
            face_right = false;
            face_down = false;
            face_left = false;
        }
    }

    if (Input.GetKey("right")){
        if (face_up){
            transform.eulerAngles = Vector3.forward * -90;
            face_up = false;
            face_right = true;
            face_down = false;
            face_left = false;
        }

        if (face_left){
            transform.eulerAngles = Vector3.forward * 0;
            face_up = true;
            face_right = false;
            face_down = false;
            face_left = false;
        }
    }

Answer 1

There are indeed many flaws in your code.

First you should not move your sprite by directly changing its position. There are different tools in Unity to do so, check out the Translate function. It will greatly help you since you don't need to know the current rotation of your sprite (you seem to misunderstand what is Vector3.forward). Also check out how Time.deltaTime works in this function.

Second, when rotating your sprite, you should do it relatively to its current rotation, ie add or substract 90 degrees. Look at Quaternion.Euler

Finally you don't need that much booleans. When programming you should try to avoid repetition, so when you have lots of the same code over and over, that's a good sign that you can write it better.

A solution could be something along these line. Keep in mind though that I didn't test it so the Vector3.up and the Vectors (0, 0, 90f) in Quaternion.Euler might be wrong depending on how you oriented your gameplay:

    if (Input.GetKeyDown(KeyCode.UpArrow))
    {
        transform.Translate(Vector3.up * Time.deltaTime);
    }
    if (Input.GetKeyDown(KeyCode.RightArrow))
    {
        transform.rotation *= Quaternion.Euler(0, 0, 90f);
    }
    if (Input.GetKeyDown(KeyCode.LeftArrow))
    {
        transform.rotation *= Quaternion.Euler(0, 0, -90f);
    }