How do I give my ejected bullet shell a speed plus the player's current speed?

Question

If my player is running around in the game and I eject a shell from his gun when I fire, how do I make sure the speed the shell travels is in addition to the speed the player is already moving?

Basically, I want it to always look like the shell is flying out and off to the right of the gun regardless of what direction the player is running around in or how fast they are moving, as it looks wrong just now with the shell looking like it's flying more to the left if I move right and more to the right if I move left, so I want to set the shell's speed on top of whatever speed the player is already moving in whatever direction.

You know, like if I throw something while stationary vs in a vehicle moving at 60mph, the object will travel at its normal speed plus my current speed so it will actually be moving faster if I throw it from the moving car.

Answer 1

Answer by JVene · Aug 21, 2018 at 08:37 PM

Get the Rigidbody component of the gun. Instantiate the casing, let's say it's 'c'. Get 'c's Rigidbody, then copy the gun's velocity with something like:

  c_rb.velocity = gun_rb.velocity;

Where c_rb is the casing's Rigidbody, and gun_rb is the gun's Rigidbody. Then apply the ejection force.

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impurekind · Aug 23, 2018 at 01:45 PM 0

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Well, I tried the following and it didn't work (the part at the bottom with "shellsRigidbody.velocity = gunsRigidbody.velocity;" says there's an error with both of those parts):

This is what I have inside my Update function:

 GameObject gun = GameObject.Find("GunNewPC");
 
             if (gun != null)
             {
                 Rigidbody gunsRigidbody;
                 gunsRigidbody = GetComponent<Rigidbody>();
             }
 
             GameObject shell = GameObject.Find("BulletShell");
 
             if (shell != null)
             {
                 Rigidbody shellsRigidbody;
                 shellsRigidbody = GetComponent<Rigidbody>();
             }
 
             Instantiate(bulletShell, transform.position, transform.rotation); // This is set to just off to the side of the gun
 
             shellsRigidbody.velocity = gunsRigidbody.velocity;

What did I do wrong?

Note: The object this script is attached to is a child of my gun object, which is in turn a child of my player object, just in case that's relevant.

JVene impurekind · Aug 23, 2018 at 06:25 PM 0

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This is a simple little issue. The gunsRigidbody and the shellsRigidbody are created inside the brackets of an 'if' statement, which means they completely evaporate outside the brackets of those 'if' statements. The are considered local (and only local) to the block of code between those brackets. The technical phrase is that they only have scope inside the brackets.

$$anonymous$$ove the declaration of Rigidbody gunsRigidbody and Rigidbody shellsRigidbody outside (and before you use them) the brackets of the if statments. This does not apply to the call to GetComponent, those are not affected or part of the problem.

Note, this means that one or the other could be null, so consider testing.

impurekind JVene · Aug 23, 2018 at 11:31 PM 0

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Note, it's not working. Here's what I have so far:

 void Update()
     {
         if (OVRInput.GetDown(OVRInput.Button.SecondaryIndexTrigger) || Input.Get$$anonymous$$ouseButtonDown(0)) // Secondary means Right Hand for Oculus Touch
         {
             audioSource.Play();
             RaycastGun();

             Rigidbody gunsRigidbody;
             Rigidbody shellsRigidbody;
 
             Instantiate(bulletShell, transform.position, transform.rotation); // This is set to just off to the side of the gun
 
             GameObject gun = GameObject.Find("GunNewVR");
             gunsRigidbody = gun.GetComponent<Rigidbody>();
 
             GameObject shell = GameObject.Find("BulletShell");
             shellsRigidbody = shell.GetComponent<Rigidbody>();
 
             shellsRigidbody.velocity = gunsRigidbody.velocity;
 
             Instantiate(gunFlash, shotOrigin.position, transform.rotation); // The barrel of the gun
         }
     }

Clearly I'm not understanding something here (and this is my trying to interpret what you're saying and put it in there correctly)--maybe there's something you think is obvious but isn't to me--so if you could just show me how it's supposed to be written properly, it really would be appreciated.

I'm not learning a single thing from all my mistakes; I'm just wasting time making a lot of mistakes.

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How do I give my ejected bullet shell a speed plus the player's current speed?

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