Simplify this code

Question

 GameObject a = new GameObject();
 GameObject b = new GameObject();
 a.transform.position = transform.position;
 b.transform.parent = a.transform;
 b.transform.localPosition = Vector3.zero;
 b.transform.localRotation = Quaternion.identity*Quaternion.Euler(180, 90, 90);
 a.transform.LookAt(target.transform);
 transform.rotation = b.transform.rotation;
 Destroy(a);
 Destroy(b);

The purpose of this code is to rotate a transform to point at an object. I want it to be as if the parent of the transform looked at the object, and the child had a local rotation of (180, 90, 90). This code does what I want, however, it creates and destroys two game objects every frame, which I'm certain is unnecessary. So, I would greatly appreciate if anyone could tell me how to rewrite this code so that it doesn't create any game objects.

Answer 1

Best Answer

Answer by Namey5 · Sep 10, 2020 at 05:32 AM

One trick when working with quaternions is to just think of them as rotations - when multiplying by a quaternion (from right to left), you are simply performing a rotation.

 //Find the rotation from our transform in the direction of the target
 Quaternion rot = Quaternion.LookRotation (target.transform.position - transform.position);
 //Set the rotation to (180,90,90) and then rotate by the look rotation
 transform.rotation = rot * Quaternion.Euler (180, 90, 90);

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Quelfth · Sep 10, 2020 at 03:11 PM 0

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What I missed yesterday was that the rot quaternion needs to be on the left of my (180, 90, 90) quaternion.

Answer 2

Answer by Aviryx · Sep 10, 2020 at 03:04 AM

without creating gameobjects at runtime? I mean you would just have the two cubes already created and reference them?

 public GameObject cube1;
 public GameObject cube2;

If you're problem is running the code inside Update you could do something like this: (You could either do something to the cubes in Update after the gameobjects are created, or invoke a method that does something)

 public class SomeClass : Monobehaviour
 {
     private bool hasCreatedGameObjects;

     void Update()
     {
         if (!hasCreatedGameObjects)
         {
              hasCreatedGameObjects = true;

              GameObject a = new GameObject();
              GameObject b = new GameObject();

              DoSomethingWithCubes(); // call a method that does something to the cubes
         }

          // or do something with cubes per frame
     }
 }

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Quelfth · Sep 10, 2020 at 04:28 AM 0

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No, it's not that I'm trying to avoid creating them at runtime, I'm trying to avoid them existing at all.

You've failed to answer my question for two reasons: 1) You're still creating game objects. 2) You're code doesn't do what mine does.

Simplify this code

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