NullReferenceException

Unity Courses Ask
#1

This newest lesson seems to have caused me some issues. When targeting my new ability, I get an error that reads “NullReferenceException: Object reference not set to an instance of an object
RPG.Combat.Projectile.GetAimLocation () (at Assets/OurScripts/Combat/Projectile.cs:50)
RPG.Combat.Projectile.Start () (at Assets/OurScripts/Combat/Projectile.cs:25)”

I checked the enemy in the ability’s effect radius and he has a collider, which is set to be a trigger. Not sure where else to look. My code should be identical to Sam’s, since I copied and pasted it exactly once I saw I had issues to check if it would fix anything.

#2

When I say “Exactly” I mean my SpawnProjectile code specifically

#3

The problem is on line 50. Check what is on that line and you can determine what could be null

#4

Lines 48 to 56 read:

private Vector3 GetAimLocation()

        {

            CapsuleCollider targetCapsule = projTarget.GetComponent<CapsuleCollider>();

            if(targetCapsule == null)

            {

                return projTarget.transform.position;

            }

            return projTarget.transform.position + Vector3.up * targetCapsule.height / 1.8f;

        }

But the target has a capsule collider, so I’m not sure why it isn’t registering.

#5

If I counted corectly, then it’s not the capsule collider but projTarget that’s null. You need to check if projTarget is null before trying to get components from it

#6

This is line 50

 CapsuleCollider targetCapsule = projTarget.GetComponent<CapsuleCollider>();

I just have some blank lines to make the code easier for me to read.

#7

yes, that’s what I counted. projTarget is null. You need to check that is is not null before you try to get components from it

#8

But shouldn’t the code from this lecture make sure there’s a target with these lines?

Health health = target.GetComponent<Health>();
                if (health)
                {
                    Projectile projectile = Instantiate(projectileToSpawn);
                    projectile.transform.position = spawnPosition;
                    projectile.SetTarget(health, data.GetUser(), damage);
                }
#9

The code from the official project is very similar in Projectile already from what I can tell:

 private Vector3 GetAimLocation()
        {
            CapsuleCollider targetCapsule = target.GetComponent<CapsuleCollider>();
            if (targetCapsule == null)
            {
                return target.transform.position;
            }
            return target.transform.position + Vector3.up * targetCapsule.height / 2;
        }
#10

Actually, the official code I can see in the repo checks if it’s null

        private Vector3 GetAimLocation()
        {
            if (target == null)
            {
                return targetPoint;
            }
            CapsuleCollider targetCapsule = target.GetComponent<CapsuleCollider>();
            if (targetCapsule == null)
            {
                return target.transform.position;
            }
            return target.transform.position + Vector3.up * targetCapsule.height / 2;
        }
#11

Is that the latest code? I believe I looked at the code from this particular lecture, unless I am just looking at especially old code. Either way, I will see if the version you’ve posted works.

#12

It’s the latest code in the repository.

The function is being called in Start. I’m not 100% sure about the order of events here, but Start may be called before your SetTarget is, so that will cause the issue

#13

Yeah, going through the next lecture, that’s when they start adding some of this stuff. So I will get back to this post once I do the next lecture and see if some of these issues resolve.

#14

Figured it out, it wasn’t a code issue at all. I made a very silly mistake and was using a prefab spawn effect instead of a projectile spawn effect.

#15

This topic was automatically closed 24 hours after the last reply. New replies are no longer allowed.

Privacy & Terms