Prototype - Getting Player to Jump in Unity

This week we showed an early prototype of the basic mechanics of our game. This involved getting player movement going and adding tags to the past and present game elements so the player can switch between the two environments with the push of a button.

One challenge we had was getting the player to jump appropriately. As a placeholder, in our player movement script we started with this code for jumping:

    public class moveExample : MonoBehavior {
        ...
        public float moveJump = 0.5f;
        ...
        void Update()
        {
            ...
            if(Input.GetKeyDown (KeyCode.W)){
                transform.Translate (0,moveJump,0);
            }
        }
    }

This kind of worked, but there are several problems with it.

1. You can keep pressing the jump key, and do some weird looking midair jumps.
2. When jumping, the player would actually disappear from the ground, and reappear in a new location higher up.

So for the first issue, I added the following code to make it so the player could only jump while on contact with the ground:

    public class moveExample : MonoBehavior {
        ...
        public float isGrounded = false;
        ...
        void Update()
        {
            ...
            if(Input.GetKeyDown (KeyCode.W) && isGrounded == true){
                transform.Translate (0,moveJump,0);
            }
        }

        void OnCollisionStay2D(Collision2D collision)
        {
            if(collision.gameObject.tag == "Ground"){
                isGrounded = true;
            }
        }

        void OnCollisionExit2D(Collision2D collision)
        {
            if(collision.gameObject.tag == "Ground"){
                isGrounded = false;
            }
        }
    }

I also added a "Ground" tag in Unity and added that tag to the different objects that the player could land on.

For the second issue, what I really needed to do was add a force to the player instead of changing its physical location, which looked something like this:

    public class moveExample : MonoBehavior {
        ...
        public float moveJump = 200f;
        ...
        void Update()
        {
            ...
            if(Input.GetKeyDown (KeyCode.W) && isGrounded == true){
                rigidbody2D.AddForce (transform.up * moveJump);
            }
        }
    }

Just like that, our player now jumps, and can easily be adjusted as desired with some physics tweaks.