Bullet hole random rotation and size

Question

Hi! I'm new to the Unity and I'm learning how to make a basic FPS. Right now, I'm stuck at making bullet holes have random rotation along the normal.

My code:

 public float Cooldown = 0.1f;
 float CooldownRemaining = 0;
 public float Range = 100.0f;
 public float BulletHoleOffset = 1.0f;

 public GameObject debrisPrefab;
 public GameObject BulletHole;


 // Use this for initialization
 void Start () {
     
 }
 
 // Update is called once per frame
 void Update () {
     CooldownRemaining -= Time.deltaTime;
     if (Input.GetMouseButton(0) && CooldownRemaining <= 0)
     {
         CooldownRemaining = Cooldown;
         Ray ray = new Ray(Camera.main.transform.position + Camera.main.transform.forward, Camera.main.transform.forward);
         RaycastHit hit;

         if(Physics.Raycast(ray, out hit, Range))
         {
             Vector3 hitPoint = hit.point;

             if (debrisPrefab != null)
             {
                 //Particle effect
                 Instantiate(debrisPrefab, hitPoint, Quaternion.FromToRotation(Vector3.up, hit.normal));
                 //Bullet Hole
                 Instantiate(BulletHole, hitPoint + (hit.normal * BulletHoleOffset), Quaternion.FromToRotation(Vector3.forward, hit.normal));
             }
         }
     }    
 }

I'm stuck at "Quaternion.FromToRotation(Vector3.forward, hit.normal));" since I don't know where to "plug" random rotation along the normal. I managed to get a random rotation along particular axis, but it didn't look good since it didn't align with the normal.

Similar to above. How to achive random hole size?

Thanks in advance!

Answer 1

Best Answer

Answer by Cherno · Sep 28, 2015 at 10:42 AM

Use Transform.Rotate, note that oyu can pass a parameter that tells the method to use local space (which is always the default value if you don't pass the parameter). Rotate random degrees around the local y-axis and you are set :) For the random scale, just pass a Vector3 composed of random values to the bullet Transform's localScale variable.

 //Bullet Hole
 GameObject bulletHole =  Instantiate(BulletHole, hitPoint + (hit.normal * BulletHoleOffset), Quaternion.FromToRotation(Vector3.forward, hit.normal));
 float randomRot = Random.Range(0f, 360f);
 bulletHole.transform.Rotate(bulletHole.transform.right * randomRot);
 float randomScale = Random.Range(0.5f, 1.5f);
 bulletHole.transform.localScale = new Vector3(randomScale ,randomScale ,randomScale);

EDIT: CORRECTED CODE & SOLUTION (See comments below);

 public float Cooldown = 0.1f;
       float CooldownRemaining = 0;
       public float Range = 100.0f;
       public float BulletHoleOffset = 1.0f;
       public GameObject debrisPrefab;
       public GameObject BulletHole;
       // Use this for initialization
       void Start () {
           
       }
       
       // Update is called once per frame
       void Update () {
           CooldownRemaining -= Time.deltaTime;
           if (Input.GetMouseButton(0) && CooldownRemaining <= 0)
           {
               CooldownRemaining = Cooldown;
               Ray ray = new Ray(Camera.main.transform.position + Camera.main.transform.forward, Camera.main.transform.forward);
               RaycastHit hit;
               if(Physics.Raycast(ray, out hit, Range))
               {
                   Vector3 hitPoint = hit.point;
                   if (debrisPrefab != null)
                   {
                       //Particle effect
                       Instantiate(debrisPrefab, hitPoint, Quaternion.FromToRotation(Vector3.up, hit.normal));
                       //Bullet Hole
                       GameObject bulletHole =  Instantiate(BulletHole, hitPoint + (hit.normal * BulletHoleOffset), Quaternion.identity) as GameObject;
        bulletHole.transform.rotation = Quaternion.FromToRotation(bulletHole.transform.up, hit.normal) * bulletHole.transform.rotation;
   float randomRot = Random.Range(0f, 360f);
        bulletHole.transform.Rotate(0, randomRot, 0);
        float randomScale = Random.Range(0.5f, 1.5f);
        bulletHole.transform.localScale = new Vector3(randomScale ,randomScale ,randomScale);
                   }
               }
           }    
       }

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MadAce · Sep 28, 2015 at 07:06 PM 0

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I really appreciate your help! I've managet to get random scale, which is good. Unfortunately, rotation doesn't seem to work. This is my code now:

GameObject bulletHole = Instantiate(BulletHole, hitPoint + (hit.normal * BulletHoleOffset), Quaternion.FromToRotation(Vector3.forward, hit.normal)) as GameObject;

float randomRot = Random.Range(0f, 360f); bulletHole.transform.Rotate(bulletHole.transform.right * randomRot); float randomScale = Random.Range(0.1f, 0.2f); bulletHole.transform.localScale = new Vector3(randomScale, randomScale, randomScale);

I've tried adding "...transform.right * randomRot, "Space.Self"), but saw no changes.

This is how it looks like: http://puu.sh/kruIv/6a1db77791.jpg

Cherno MadAce · Sep 28, 2015 at 08:06 PM 1

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Ok, I thought you had the normal aligment already covered.

Note that you use the following code for the alignment:

 Quaternion.FromToRotation(Vector3.forward, hit.normal));

You use Vector3, which always means world space (Vector3.forward = positive z on the z axis). You want to use local space:

 Quaternion.FromToRotation(bulletHole.transform.forward, hit.normal));

In the end, the axis you have to use depends on the bulletHole's pivot orientation, so experiement a bit and use bulletHole.transform.up if forward is the wrong axis (or even bulletHole.transform.right).

The same goes for the random rotation; experiemtn with different axes:

 bulletHole.transform.Rotate(bulletHole.transform.up * randomRot);

or

 bulletHole.transform.Rotate(bulletHole.transform.forward * randomRot);

MadAce Cherno · Sep 29, 2015 at 04:39 PM 0

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Ugh, somehow I managed to delete the comment. -_-

Unfortunately, it still doesn't work. I tried transform.up, forward and right. No dice. It just changes the rotation of the hole, but it's not aligned with the normal at all. This is what I get: http://puu.sh/ksueQ/34985c94b3.jpg On the bright side, they seem to face tghe same local axis. When I use Vector3, holes are aligned with normal, but then random rotation doesn't work. Also, on which axis does "bulletHole.transform.Rotate(bulletHole.transform.forward*randomRot)" rotate the object?

I have to ask, the original bullethole prefab (which is located in prefab folder) is zeroed out and is rotated 90 degrees on the x axis. When I run the game mode, shoot boxes a few tome, get back to edit mode, I see that original prefab (in the folder) now has random x,y,z position and rotation. Is that normal?

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MadAce · Sep 29, 2015 at 06:05 PM 0

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Unfortunately, it still doesn't work. This is what I get: http://puu.sh/ksueQ/34985c94b3.jpg No matter if I use transform.up, forward or right. It just rotates in a different way, but is never aligned with normal. On the bright side, they seem to face same local axis on any normal.

I also couldn't use "Quaternion.FromToRotation(bulletHole.transform.forward, hit.normal));" I had to use "BulletHole". I even tried rena$$anonymous$$g everything to "bulletHole" everywhere. Same thing happens. Only time I get holes to appear exactly on normal is when I use Vector3.

I also have to ask, my default prefab (located in "prefab" folder) is zeroed out and rotated 90 degrees on the x axis. But if I run the game, shoot the boxes, go back to editing, the original prefab (in the folder) now has random x,y and z rotation and position. Is this normal?

Cherno MadAce · Sep 29, 2015 at 06:30 PM 1

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Be very careful now. Look at how you named you variables.

The variable that holds a reference to your prefab is called "BulletHole". This is ONLY USED ONCE: You pass it to the Instantiate function. the temporary "bulletHole" variable is the variable that holds the clone that is instantiated, and this is also the gameobject (or rather, it's transform) for all the bulletHole.transform.up etc. rotation and whatnot operations.

To make myself even more clear:

  public float Cooldown = 0.1f;
      float CooldownRemaining = 0;
      public float Range = 100.0f;
      public float BulletHoleOffset = 1.0f;
      public GameObject debrisPrefab;
      public GameObject BulletHole;
      // Use this for initialization
      void Start () {
          
      }
      
      // Update is called once per frame
      void Update () {
          CooldownRemaining -= Time.deltaTime;
          if (Input.Get$$anonymous$$ouseButton(0) && CooldownRemaining <= 0)
          {
              CooldownRemaining = Cooldown;
              Ray ray = new Ray(Camera.main.transform.position + Camera.main.transform.forward, Camera.main.transform.forward);
              RaycastHit hit;
              if(Physics.Raycast(ray, out hit, Range))
              {
                  Vector3 hitPoint = hit.point;
                  if (debrisPrefab != null)
                  {
                      //Particle effect
                      Instantiate(debrisPrefab, hitPoint, Quaternion.FromToRotation(Vector3.up, hit.normal));
                      //Bullet Hole
                      GameObject bulletHole =  Instantiate(BulletHole, hitPoint + (hit.normal * BulletHoleOffset), Quaternion.identity) as GameObject;
       bulletHole.transform.rotation = Quaternion.FromToRotation(bulletHole.transform.up, hit.normal) * bulletHole.transform.rotation;
  float randomRot = Random.Range(0f, 360f);
       bulletHole.transform.Rotate(bulletHole.transform.up * randomRot);
       float randomScale = Random.Range(0.5f, 1.5f);
       bulletHole.transform.localScale = new Vector3(randomScale ,randomScale ,randomScale);
                  }
              }
          }    
      }

MadAce Cherno · Sep 29, 2015 at 06:52 PM 0

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I'm starting to believe it's not possible to achive. I literally copy-pasted your code and it gave me this error: http://puu.sh/ksDtL/79009a4686.png

Bullet hole random rotation and size

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