How do I get and manipulate Transform values without changing the original Transform?

Question

I want to add spread and inacurracy to my top-down shooter. The bullets spread as they should, but my gun kinda wiggles because it thinks I'm changing its Transform. My code so far looks like this:

 protected void InstantiateBullet(float spread)
 {
     Transform clickTransform = transformAtClick;

     float deviation = Random.Range(-inaccuracy, inaccuracy);
     float actualAngle = clickTransform.eulerAngles.z;
     Vector3 euler = Vector3.forward * (actualAngle + spread + deviation);

     clickTransform.rotation = Quaternion.Euler(euler);

     GameObject bullet = Instantiate(bulletPrefab, firePoint.position, clickTransform.rotation);

     Rigidbody2D rb = bullet.GetComponent<Rigidbody2D>();
     rb.AddForce(clickTransform.right * bulletSpeed * Time.fixedDeltaTime, ForceMode2D.Impulse);
 }

What I think is the problem is that all Transforms store a reference to gameObject.transform, but I'm not sure. Honestly, I don't know how to provide any further information, so I hope this is enough.

Answer 1

Best Answer

Answer by Namey5 · Nov 18, 2020 at 05:59 AM

A Transform is a class, which in C# means that it is a reference type. As such, setting a Transform equal to another Transform doesn't make a new copy, it just points to the same Transform (which is why adjusting a value on either will change the original). In this case, you don't even need a Transform at all and can just use vectors and quaternions to get your desired rotation;

  protected void InstantiateBullet(float spread)
  {
      float deviation = Random.Range(-inaccuracy, inaccuracy);
      Quaternion clickRotation = Quaternion.AngleAxis (transformAtClick.eulerAngles.z + spread + deviation, Vector3.forward);
      GameObject bullet = Instantiate(bulletPrefab, firePoint.position, clickRotation);
      Rigidbody2D rb = bullet.GetComponent<Rigidbody2D>();
      rb.AddForce((clickRotation * Vector3.right) * bulletSpeed * Time.fixedDeltaTime, ForceMode2D.Impulse);
  }

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theProdWorm · Nov 18, 2020 at 01:19 PM 0

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Thank you very much, this works perfectly!

I did search a lot beforehand and found out the difference between classes and structs, and tried making a struct out of the Transform object. Of course, this did not work. I did figure out I should just use Quaternions and Vectors but I just couldn't figure out how rotation works. The point where I gave up was when I read something about Quaternions using a fourth dimension. Why do they have to be so complicated?...

Answer 2

Answer by MurphyMurph_21 · Nov 18, 2020 at 06:03 AM

I think if you add the euler rotation to the firePoint.position instead of the clickTransform.position it should work @theProdWorm

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theProdWorm · Nov 18, 2020 at 01:24 PM 0

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Thing is, the firePoint is the reference that the transformAtClick gets when I click the fire button. What I tried to do was get a copy of the firePoint, but no matter what I did, I'd get a reference to it instead.

How do I get and manipulate Transform values without changing the original Transform?

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