Projectiles not moving, and not starting from the player (Unity 2D / C#)

Question

INFO
So I am trying to make a top-down endless arena battle game, where your shield acts also as your means of offense. The shield should spawn infront of the player, and stay infront as the player moves and rotates (while holding down mouse1 (which it does)). Once mouse1 is released, the shield should shoot forward as a projectile.

PROBLEM
However, when mouse1 is let go of, the shield moves forward a small bit and then freezes, but no matter where the player is, they move as if the player is at 0, 0.

( I know this is a bit confusing so here is a photo: )
( The triangle is the player )

CODE
This is my player controller script:

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

public class PlayerController : MonoBehaviour
{
    public Rigidbody2D rb;

    public GameObject Shield;

    public float moveSpeed = 4.3f;
    public float sheildSpeed = 2f;
    
    Vector2 movement;

    bool isDead = false;

    void Update()
    {
        movement.x = Input.GetAxisRaw("Horizontal");
        movement.y = Input.GetAxisRaw("Vertical");

        Vector3 mouseScreen = Input.mousePosition;
        Vector3 mouse = Camera.main.ScreenToWorldPoint(mouseScreen);

        transform.rotation = Quaternion.Euler(0, 0, Mathf.Atan2(mouse.y - transform.position.y, mouse.x - transform.position.x) * Mathf.Rad2Deg - 90); 

        if (Input.GetMouseButtonDown(0)) {
            Shield = Instantiate(Shield, transform.position + transform.forward + transform.up, transform.rotation);
            Shield.transform.parent = transform;
        }

        if (Input.GetMouseButtonUp(0)) {
            Shield.transform.parent = null;
        } 
    }

    void FixedUpdate() {
        if (!isDead) {
            rb.MovePosition(rb.position + movement * moveSpeed * Time.fixedDeltaTime);
        }
    }
}

and this is the sheild script:

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

public class ShieldController : MonoBehaviour
{
    public float sheildSpeed = 2f;

    void FixedUpdate()
    {
        this.GetComponent<Rigidbody2D>().MovePosition(this.transform.up * sheildSpeed);       
    }
}

NOTE
I hope have provided enough information for you to be able to help me, but if you need / want more details just leave aaa comment and I will hopefully reply with whatever you need :)

score 1 · Accepted Answer · 2021-09-07T12:07:38.433

Hey I tested this in my own project and got it working

Change this

void FixedUpdate()
{
    this.GetComponent<Rigidbody2D>().MovePosition(this.transform.up * sheildSpeed);       
}

Into this

public void LaunchForward(float speed)
{
    this.GetComponent<Rigidbody2D>().velocity = transform.up * speed;
}

I also edited the spawning a bit into this

public GameObject Shield;
public GameObject ShieldInstance;

if (Input.GetMouseButtonDown(0))
    {
        if (ShieldInstance != null) { return; }
        ShieldInstance = Instantiate(Shield, transform.position + transform.forward + transform.up, transform.rotation);
        ShieldInstance.transform.parent = transform;
    }

if (Input.GetMouseButtonUp(0))
    {
        ShieldInstance.transform.parent = null;
        ShieldInstance.GetComponent<ShieldController>().LaunchForward(5f);
        Destroy(ShieldInstance, 3f);
    }

But the primary problem was the physics on the shield itself, the code was colliding with 2 functions which caused the weird behaviour I think

Edit: Setting the velocity is required only once, so a dedicated method is appropriate here (credit derHugo). Although you could have this method in the player class, having it in its own class is better if you want to have more complex behaviour in your game

Setting the velocity in `FixedUpdate` is quite unnecessary .. would be enough to do so exactly **once** ... Instead of the `if (this.transform.parent != null) { return; }` I would rather do it via a dedicated method you call when release the button — derHugo, Sep 07 '21 at 06:50
Hi you're right, I'll edit the post above to append these changes — , Sep 07 '21 at 12:01

Projectiles not moving, and not starting from the player (Unity 2D / C#)

1 Answers1