How to prevent the player to move beyond certain x-position value

Questions & Answers
1

Hey,

I’m pretty new to Unity and I’m currently working on a 3D asteroid evasion game.
The player is piloting a ship through an asteroid field. The ship moves constantly forward and the player can only navigate up, down, left and right.
As I don’t want to make an infinite asteroid field, I want my player to stay inside the field and stop him from moving out of it. The field goes from -10 to 10 on the X and -10 to 10 on the Y.
I want to track the player position and if he moves past the -10 or 10 on the X position, his x-position should be set to 10 (or -10). Same on the Y-position.
Any idea on how to do that in C#?

Thanks and best,
Mat

2

You answered your own question,Just write:

If (transform.position.x < 10)
{
transform.position.x = 10
}

Four times for x,y axis (Positive and negative value)

3

You can do this 2 ways:

  1. use colliders and place them on the boundaries of your screen (make sure they’re not isTrigger). This will be easier and a more preferable way to do it

  2. in code, you could set constraints of your spaceship:

    if(transform.position.x > 10)
    {
    transform.position.x = 10;
    }
    else if(transform.position.x < -10)
    {
    transform.position.x = -10;
    }

    if(transform.position.y > 10)
    {
    transform.position.y = 10;
    }
    else if(transform.position.y < -10)
    {
    transform.position.y = -10;
    }

4

Ok I’ve got it to work now.

this is the final, working code:

using UnityEngine;

public class PlayerMovement : MonoBehaviour {

    public Rigidbody player;

    public float forwardForce = 2000f;
    public float sidewaysForce = 500f;
    void SetTransformX(float n)
    {
        player.transform.position = new Vector3(n, player.transform.position.y, player.transform.position.z);
    }
    void SetTransformY(float n)
    {
        player.transform.position = new Vector3(player.transform.position.x, n, player.transform.position.z);
    }

    // Update is called once per frame
    void FixedUpdate () {

        player.AddForce(0, 0, forwardForce * Time.deltaTime);

        if (Input.GetKey("d"))
        {
            player.AddForce(sidewaysForce * Time.deltaTime, 0, 0, ForceMode.VelocityChange);
           
        }

        if (Input.GetKey("a"))
        {
            player.AddForce(-sidewaysForce * Time.deltaTime, 0, 0, ForceMode.VelocityChange);
          
        }

        if (Input.GetKey("w"))
        {
            player.AddForce(0, sidewaysForce * Time.deltaTime, 0, ForceMode.VelocityChange);
        }

        if (Input.GetKey("s"))
        {
            player.AddForce(0, -sidewaysForce * Time.deltaTime, 0, ForceMode.VelocityChange);
        }
        if (player.transform.position.x >= 10) { SetTransformX(10.0f); player.velocity = new Vector3(0, player.velocity.y, player.velocity.z); }
        if (player.transform.position.x <= -10) { SetTransformX(-10.0f); player.velocity = new Vector3(0, player.velocity.z, player.velocity.z); }
        if (player.transform.position.y <= 0) { SetTransformY(0.0f); player.velocity = new Vector3(player.velocity.x, 0, player.velocity.z); }
        if (player.transform.position.y >= 10) { SetTransformY(10.0f); player.velocity = new Vector3(player.velocity.x, 0, player.velocity.z); }
    }
}

— old response —

Ok, I might need to clarify my struggle a bit.
I understand the code you guys posted and that is also what I had in mind, but I don’t know how to do it with the code I currently have.

This is my current player movement code:

using UnityEngine;

public class PlayerMovement : MonoBehaviour {

    public Rigidbody player;

    public float forwardForce = 2000f;
    public float sidewaysForce = 500f;
    // Update is called once per frame
    void FixedUpdate () {

        player.AddForce(0, 0, forwardForce * Time.deltaTime);

        if (Input.GetKey("d"))
        {
            player.AddForce(sidewaysForce * Time.deltaTime, 0, 0, ForceMode.VelocityChange);
            player.transform.Rotate(0, 0, 20 * Time.deltaTime);
        }

        if (Input.GetKey("a"))
        {
            player.AddForce(-sidewaysForce * Time.deltaTime, 0, 0, ForceMode.VelocityChange);
            player.transform.Rotate(0, 0, -20 * Time.deltaTime);
        }

        if (Input.GetKey("w"))
        {
            player.AddForce(0, sidewaysForce * Time.deltaTime, 0, ForceMode.VelocityChange);
        }

        if (Input.GetKey("s"))
        {
            player.AddForce(0, -sidewaysForce * Time.deltaTime, 0, ForceMode.VelocityChange);
        }

    }
}

If I use this simple code-snippet:

if (player.transform.position.x >= 10) { player.transform.position.x = 10; }

Visual Studio gives me the following error:

player.transform.position.x is not a variable and therefore cannot be changed

so this seems not to work… :-/