CODEWITHSUNDEEP
c#unity-game-engine
33_Munir_33
33_Munir_33

Reputation: 23

OnCollisionStay not working in 2D movement script

So, I'm still not the best at this but I'm trying to use this script for 2D movement but the jumping isn't working for some reason. It keeps saying that the OnCollisionEnter function "is declared but never used". Can someone tell me what im doing wrong? Thanks

If I remove the (Collision col) part it says that "void cannot be used in this context".

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class RonyWalking : MonoBehaviour
{
Rigidbody2D rigid;
SpriteRenderer sprite;
public bool isJumping;
public float spd = 2.0f;


// Start is called before the first frame update
void Start()
{
    rigid = GetComponent<Rigidbody2D>();
    sprite = GetComponent<SpriteRenderer>();
}

// Update is called once per frame
void Update()
{
    if(Input.GetKey("d")){rigid.velocity = new Vector2(spd, 0);}
    else if(Input.GetKey("a")){rigid.velocity = new Vector2(-spd, 0);}

    if(Input.GetKeyDown("w") && isJumping == false)
    {
        rigid.velocity = new Vector2(0, 5);
        isJumping = true;

    }

    void OnCollisionStay(Collision col)
    {
    isJumping = false;
    }

}
}

Upvotes: 1

Views: 953

Answers (1)

Fredrik
Fredrik

Reputation: 5108

When using 2D physics, you need to use the 2D lifecycle methods;

void OnCollisionStay2D(Collision2D col) 
{
    isJumping = false;
}

And you shouldn't put this method inside your Update method... It should be on class level:

public class RonyWalking
{

    void Update() 
    {
        // ...
    }

    void OnCollisionStay2D(Collision2D col) 
    {
        // ...
    }
}

Don't worry about "Is declared but never used", this may be because you don't have specific code referencing the method, but Unity will raise events that calls it, "automagically"

Another thing that I can see while reading your code, that may be unintentional behaviour for you, is that when clicking left/right, you set velocity UP to 0, and when clicking up you set LEFT/RIGHT velocity to 0; this will result in freezing the movement mid-air if you jump, then move while in air:

  1. Click D; velocity = 2, 0
  2. Click W; velocity = 0, 5
  3. Character will now move upwards until another input is given
  4. Click D; velocity = 2, 0 and the character will continue moving while in air because when moving sideways the up/down velocity is set to 0

enter image description here

To solve this, either set the other to existing velocity or make the inputs manipulate a Vector that you then apply at the end of the movement code:

Vector2 existingMovement = rigid.velocity;

if (Input.GetKey(KeyCode.D)) 
    existningMovement.x = spd;
else if (Input.GetKey(KeyCode.A))
    existningMovement.x = -spd;

if (Input.GeyKeyDown(KeyCode.W) && !isJumping) 
{
    existningMovement.y = 5f;
    isJumping = true;
}

Furthermore, I think you may have some unexpected behaviour with OnCollisionStay; it will fire every frame that you're colliding with the ground, I assume. But I think it may also fire a frame or two AFTER you've jumped since the physics of your character will not INSTANTLY leave the collision, so isJumping will be set to false even after your jump, letting you jump while in the air one more time.

I would recommend that you use OnCollisionExit2D(Collision2D col) to set isJumping = true instead, or OnCollisionEnter2D(Collision2D col) and set it to isJumping = false, depending on the functionality you desire (if you want the ability to jump after walking out of a cliff)

Upvotes: 1

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