Invoke | Official Unity Discord | Page 1

silk stone Oct 28, 2022, 2:30 PM

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All the more reason to help you understand this faster

inland nest Oct 28, 2022, 2:31 PM

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

public class JumpPad : MonoBehaviour
{
   
    private float bounce = 12f;

    private void OnCollisionEnter2D(Collision2D collision)
    {
        Invoke("bounce", 2);
    }
    void FixedUpdate()
    {
        if (collision.gameObject.CompareTag("Player"))
        {
            collision.gameObject.GetComponent<Rigidbody2D>().AddForce(Vector2.up * bounce, ForceMode2D.Impulse);
        }
    }

    
}

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Oh hey, it works, awesome

silk stone Oct 28, 2022, 2:32 PM

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I'm pretty sure that code above doesn't work? 🤔

inland nest Oct 28, 2022, 2:32 PM

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It indeed doesnt

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The name 'collision' doesnt exist in current context

silk stone Oct 28, 2022, 2:33 PM

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In the documentation for Invoke()
https://docs.unity3d.com/ScriptReference/MonoBehaviour.Invoke.html

void Start()
{
    Invoke("LaunchProjectile", 2.0f);
}

void LaunchProjectile()
{
    // Do stuff
}

silk stone Oct 28, 2022, 2:34 PM

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inland nest The name 'collision' doesnt exist in current context

Indeed, you've made a weird change.
What you have done since last time is move the code from inside OnCollisionEnter2D
into FixedUpdate()

I will explain first how to simply make this work.
And then why what you did with FixedUpdate was wrong.

inland nest Oct 28, 2022, 2:34 PM

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Okay, that sounds good

silk stone Oct 28, 2022, 2:34 PM

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Now, read my example of Invoke

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The example uses Start() to run Invoke
Start() runs automatically when an object has been enabled for the first time in a scene

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Invoke takes the name of a method in its parameter.
If either the parameter name or the method name do not match, the code will return an error.

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A better way of writing it would be

Invoke(nameof(LaunchProjectile), 2.0f)

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Anyway.
You don't want to execute the jump effect via Start
You want it to execute 2 seconds after one collider has touched another

inland nest Oct 28, 2022, 2:38 PM

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Correct

silk stone Oct 28, 2022, 2:41 PM

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public class JumpPad : MonoBehaviour
{
    private float bounce = 12f;

    private void OnCollisionEnter2D(Collision2D collision)
    {
        if (collision.gameObject.CompareTag("Player"))
        {
            Rigidbody2D rb = collision.gameObject.GetComponent<Rigidbody2D>();
            Bounce_Effect(rb);
        }
    }

    private void Bounce_Effect(Rigidbody2D rb)
    {
        rb.AddForce(Vector2.up * bounce, ForceMode2D.Impulse);
    }
}

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This will make it happen instantly, without delay

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Since we need a reference to the Player's Rigidbody, it would make more sense to have this script on the player, rather than each JumpPad in the game.

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In order to modify this one (same approach)

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you'll need to store a private reference to the rigidbody, because we can't pass parameters with Invoke

inland nest Oct 28, 2022, 2:45 PM

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silk stone Since we need a reference to the Player's Rigidbody, it would make more sense to...

And change "Player" to "JumpPad" ? If I give the JumpPad a JumpPad tag, ofcourse

silk stone Oct 28, 2022, 2:46 PM

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inland nest And change "Player" to "JumpPad" ? If I give the JumpPad a JumpPad tag, ofcourse

Yes, exactly.

inland nest Oct 28, 2022, 2:47 PM

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I see now, and if I wanted to delay this, I should Invoke the Bounce_Effect, to my understanding?

silk stone Oct 28, 2022, 2:47 PM

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Yes, but there is one problem: We can't pass values when using invoke

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Therefore

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public class JumpPad : MonoBehaviour
{
    private float bounce = 12f;
    private Rigidbody2D rb;  // <--- Added this
    private void OnCollisionEnter2D(Collision2D collision)
    {
        if (collision.gameObject.CompareTag("Player"))
        {
            rb = collision.gameObject.GetComponent<Rigidbody2D>();
            Bounce_Effect();
        }
    }

    private void Bounce_Effect()
    {
        rb.AddForce(Vector2.up * bounce, ForceMode2D.Impulse);
    }
}

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And I'll leave replacing Bounce_Effect() with Invoke to you :)

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That code is without changing Player/JumpPad

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To explain what was changed:

private int o;  // This is a variable field, accessible to only this instance of the script
private void Some_Method()
{
    int i = 0;  // This is a local variable, only accessible from inside the parent method
}

inland nest Oct 28, 2022, 2:55 PM

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But if I change private void Bounce_Effect() to private void Invoke(), the code doesnt make sense anymore

silk stone Oct 28, 2022, 2:55 PM

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Post what you changed.

inland nest Oct 28, 2022, 2:56 PM

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I am actually not sure what to change

silk stone Oct 28, 2022, 2:56 PM

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Doesn't matter. Show me what you did change. I'll explain why that doesn't make sense.

inland nest Oct 28, 2022, 2:57 PM

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In non-coding language, you 'create' Bounce_Effect in private void oncollisionenter2d, and then you say what Bounce_Effect means in private void Bounce_Effect, correct?

silk stone Oct 28, 2022, 2:58 PM

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This is creating Bounce_Effect:

    private void Bounce_Effect()
    {
        rb.AddForce(Vector2.up * bounce, ForceMode2D.Impulse);
    }

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it stays as it is

inland nest Oct 28, 2022, 2:58 PM

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Yes

silk stone Oct 28, 2022, 2:59 PM

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Inside the collision call, we are calling Bounce_Effect() to be run, if the conditions are met

    private void OnCollisionEnter2D(Collision2D collision)
    {
        if (collision.gameObject.CompareTag("Player"))
        {
            rb = collision.gameObject.GetComponent<Rigidbody2D>();
            Bounce_Effect();
        }
    }

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This calls the method instantly.

Bounce_Effect();

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Invoke can run any method, by inputting its name, and can have a delay.

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So you remove Bounce_Effect(); and replace it with Invoke(...);

inland nest Oct 28, 2022, 3:02 PM

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I think that was my biggest issue; understanding that you have to reference Invoke right after the conditions are met (also lack of proper coding knowledge).
It works like charm

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I cannot thank you enough for helping me today, you are a lifesaver and a very kind person, I wish there were more of you :}

silk stone Oct 28, 2022, 3:03 PM

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It's just a ridiculous amount of logic to absorb, and mindfucks to correct, when starting out.
Hope this helps build some starting point for you.

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Any questions?

silk stone Oct 28, 2022, 3:03 PM

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inland nest I cannot thank you enough for helping me today, you are a lifesaver and a very k...

You're welcome 👍

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