Develop Reference

Cannot convert vector3 to collider?

I'm trying to make a 3D racing game on Unity and I am currently looking to program checkpoints. Right now I have hit a roadblock in which I can't convert vector3 to collider. Any advice?
private void OnTriggerEnter3D(Collider Checkpoint)
{
if (Checkpoint.tag == "Checkpoint")
{
Checkpoint = transform.position;
}
}

Checkpoint is a Collider data type. Try it with Checkpoint.transform.position

A Collider is not at all a Vector3. I invite you to read the documentation for both types to understand better what each is used for.
As mentioned in another comment, if you want to access a Collider position, you should use Collider.transform.position (so
Checkpoint.transform.position
in your case). A Collider component should be attached to the object your rigidbody is supposed to collide to.
If you want the Collider to respond phisically to impacts, as mentioned in the documentation, you should attach a Rigidbody to it.

Unity Physics.Raycast with LayerMask does not detect object on layer. Used bitshifting, tried inverting layer, still nothing works

novice to intermediate Unity developer here. I've been hitting a pretty significant roadblock the past ~2 days concerning the raycast detection of objects with specific layers. I've been researching this issue quite a lot, and all the solutions I've found don't seem to reflect the strange issue I'm facing.
Basically, the problem follows this sequence of events:
My player character has a vision cone shaped trigger mesh called 'InSightBox' which detects all objects with the tag 'Mob' and adds them to a List of colliders called 'MobsInRange'.
public List<Collider> mobsInRange;
public List<Collider> GetColliders()
{
return mobsInRange;
}
// Start is called before the first frame update
void Start()
{
mobsInRange = new List<Collider>();
}
// Update is called once per frame
void Update()
{
}
//add enemy with tag 'mob' to list
private void OnTriggerEnter(Collider other)
{
if(!mobsInRange.Contains(other) && other.tag == "Mob")
{
mobsInRange.Add(other);
}
}
//remove enemy with tag 'mob' to list
private void OnTriggerExit(Collider other)
{
if (mobsInRange.Contains(other) && other.tag == "Mob")
{
mobsInRange.Remove(other);
}
}
This list is then fed up to the root/parent player game object containing everything relating to the player.
public Transform closestMob;
public List<Collider> mobs;
public Transform GetClosestEnemy()
{
Transform tMin = null;
float minDist = Mathf.Infinity;
Vector3 currentPos = transform.position;
foreach(Collider trans in mobs)
{
//find enemy with closest distance and set tMin to it. Method returns tMin
float dist = Vector3.Distance(trans.transform.position, currentPos);
if(dist < minDist)
{
tMin = trans.transform;
minDist = dist;
}
}
//Debug.Log(tMin);
return tMin;
}
The player then uses a 'Look at' method to find the closest of all 'mobs' to the player. The player will set their forward transform to look at the closest mob.
Problem Step ---> 4) When the player raises their gun and attempts to shoot the closest enemy, a ray is cast with a layermask that looks only for objects on the layer 'Enemy', the 8th layer. When the ray detects the enemy, the enemy script should fire its 'TakeDamage' method which decreases the 'curHealth' variable by 8. Only problem is, the cast doesn't seem to detect the enemy object on the 'Enemy' layer.
LayerMask layerMask = 1 << 8;
void Fire()
{
//play the audio of the gunshot
StartCoroutine("SetPlaying");
RaycastHit hit;
//cast a ray from the player forward and check if the hit object is on layer 'Enemy'
if (Physics.Raycast(transform.position, transform.forward, out hit, Mathf.Infinity, layerMask))
{
//if hit object is an enemy, set its 'gotShot' bool to true
print("hit enemy");
closestMob.GetComponent<EnemyBase>().gotShot = true;
}
//play gunshot sound and stop player from turning
source.clip = fireSound;
source.PlayOneShot(fireSound, gunshotVolumeScale);
turnSpeed = 0;
}
I'll also note that all the solutions I've seen to this issue are not working for me. I declared an int variable called 'layerMask' and initialized it in Awake() by bit shifting layer 8 into it (i.e. int layerMask = 1 << 8), but it still isn't detecting it. The enemy contains all that I belive it should need for this to work, including a rigidbody, a capsule collider, the associated scripts, as well as being on the 'Enemy' layer.
This is where it gets weird (at least to my knowledge), when I invert the mask in the cast (~layerMask), it does exactly what I'd expect, and begins firing the code within the raycasts if statement when the player 'shoots' anything that doesn't have the 'Enemy' layer.
Any help would be suuuper appreciated as I'm getting to the point of slamming my face into the desk :/
Side Note: I'm getting to the point where I may just attach a 'fire range' cube trigger to my player and enabled it when the Fire() event is triggered, then have that check for game objects with the tag 'mob' as that kind of detection works most consistent to me.

First, be sure that you didn't confuse layers with tags. They are different.
Second, get rid of any implicit actions and references, i.e. don't use bitshifting, layer indices, or any non-straightforward reference. Instead, create something like this:
[SerializedField] private LayerMask _layerMask;
Use inspector to assign needed layer(s).
This way you will explicitly see, which layer you are using. This is useful not only for you, but for you in future, when you forget layers' indices. Also, for anyone who aren't familiar with the project.
Third is for debug. Be sure that your raycasting works as intended at other aspects:
Try remove layerMask and see if the ray goes where you want it to
Use custom gizmos to check if you cast the ray in a right direction
Try using RaycastAll. Maybe some objects catch (block) your ray earlier than you think

Looks like the issue was that I had my 'Enemy' prefab which contained the necessary components (RigidBody, Collider, scripts, NavmeshAgent) nested inside an empty game object. I thought at first to make something a prefab you needed to have it inside an Empty. I see now that is rather redundant and not necessary (at least in my case).
Physics.RaycastAll solved this issue as it no longer got 'halted' by the parent empty's collider and also hit the child.
I actually got it working just using a regular Physics.Raycast by rebuilding the Enemy prefab as just a single Capsule object (which I'll replace with character meshes later on).
Side Note
Before I got this new method working, I also used a different one that achieves the same goal in a pretty lightweight manner.
I added a long and thin box trigger to the front of my player so that it has enough distance to collide with any enemies within the shooting range.
I then enable the trigger any time the player enters their 'Aiming' state. If the trigger collides with any mesh that has the tag "Mob', it sets a bool on the player that indicates if the enemy is in range.
Then if the enemy is in range && the player enters the 'Firing Gun' state, a method in the Enemy Base script is fired that decrements the enemy health by a publicly decided variable called damagetaken.
Both the Raycast method and the box trigger method work equally well for me, but the box trigger one just took less time to figure out and gave me less headache haha.
Hope this helps anyone else in a bind!!!!!

OnCollisionEnter not working with duplicate of an object

So I have a wall where the player can jump on and it detect the collision and reduce the gravity. This is working fine.
This is what it looks like
Mossy Wall (L)
and here is the code:
private void OnCollisionEnter2D(Collision2D collision)
{
if (collision.gameObject.CompareTag("MossWall"))
{
onMossyWall = true;
}
}
private void OnCollisionExit2D(Collision2D collision)
{
if (collision.gameObject.CompareTag("MossWall"))
{
onMossyWall = false;
}
}
As you can see it's pretty basic, all I want is to set onMossyWall to true when there is a collision and it works perfectly for this one.
Now I want to do the same but for an opposite wall, I copy the object (Moss Walls (R)), and rotate the platform effector so that it's on the opposite direction, and yet nothing happens. onMossyWall stay false. The tag is the same and the object is basically the same as the first one, why isn't this working ?
Mossy Wall (R)
I assume I must have forgotten something stupid but I have been looking for solutions for a while and I found nothing that works. I tried with a different tag but still nothing.

As unity docs states:
OnCollisionEnter is called when this collider/rigidbody has begun
touching another rigidbody/collider.
So please make sure you have colliders on both objects and one of the object must have a rigidbody.

How can I access the component of an instantiated object in Unity?

Ok so here's what's happening
I have this "Bullet" script with an "ApplyForce" method, attached to a Bullet prefab
public void ApplyForce (Vector2 direction)
{
const float magnitude = 5f;
GetComponent<Rigidbody2D>().AddForce(magnitude * direction, ForceMode2D.Impulse);
}
And a "Ship" script that will instantiate a Bullet and try to access its "Bullet" component to then access the "ApplyForce" method to apply a force in the same direction the ship is facing
// check for shooting input (left ctrl key) and fire
if (Input.GetKeyDown(KeyCode.LeftControl))
{
GameObject bullet = Instantiate(bulletPrefab, transform.position, transform.rotation);
bullet.GetComponent<Bullet>().ApplyForce(thrustDirection);
}
Problem is, it doesn't work. It sends this error:
NullReferenceException: Object reference not set to an instance of an object
Ship.Update () (at Assets/scripts/Ship.cs:56)
I get that my problem is how to properly access the newly instantiated GameObject, but I couldn't find a proper way to do it. So here I am asking for your assistance.
I apologize for any newbie mistake that may anger you as I am fairly new to coding/programming and have next to 0 experience with this

Ok guys I found the problem: I am an absolute idiot! :D
I forgot to attach the Bullet script to the Bullet prefab

which line is line 56? one common thing you can try is:
bullet.GetComponentInChildren<Bullet>().ApplyForce(thrustDirection);
if that still doesn't work and that is line 56, make sure that the 'thrustDirection' variable is not null.

Object not being destroyed when shot with a bullet - UNITY3D C#

So in my game, there's a gun that sprays bullets, and I'm trying to make a gameObject destroy on collision with the bullets. The bullets are based off of one gameObject (Capsule). I've tried these two scripts so far:
using UnityEngine;
using System.Collections;
public class whenshot : MonoBehaviour {
void OnCollisionEnter(Collision col)
{
if (col.gameObject.name == "Bullet")
{
Destroy(col.gameObject);
}
}
}
and:
using UnityEngine;
using System.Collections;
public class whenshot : MonoBehaviour {
void OnCollisionEnter(Collision col)
{
if (col.gameObject.name == "Bullet")
{
Destroy(this); //the difference between the two is that I changed "col.gameObject" to "this"
}
}
}
I'm shooting the object but it's not disappearing/destroying itself. How can I fix this?
Here's a visual if it helps:

this refers to the object instance of the caller (this is basic OOP), i.e., whenshot, and not gameObject. So the second sample is effectively Destroying the instance of the script from the gameObject it is attached to.
The first script is technically fine, and should work, provided these conditions are met:
Either the projectile (bullet) or the target (or both) have a non-kinematic rigidbody component attached. (Unity docs.)
Both have 3D Collider components.
The name of every single bullet gameObject that collides with the target is exactly "Bullet".
All projectile objects have this script as a component.
Some suggestions
Use prefabs and tags: take your bullet primitive and store it as a prefab. Add a tag to the prefab called "Bullet". Do the same for the target and tag it as "Target". Tag the player as "Player". In the "gunController", set a reference to the bullet prefab and make it Instantiate bullets on whatever trigger you're using. In the bullet's script, use CompareTag("Target") instead of == and Destroy both the target gameObject and this.gameObject.
It seems to me that the above is the behaviour you want. If that is the case, there is no delay between collision and destruction, and hence no need to simulate physics whatsoever. Unless you have some other physics interactions with bullets/targets, mark the one without a rigidbody as a Trigger.
A Strong Suggestion
Go through Unity tutorials.

This is an example from a 2D Game I made a while back, but i think it might help.
void OnTriggerEnter2D(Collider2D other)
{
if (other.tag == "Destroyable")
{
Destroy(other.gameObject);
}
}
I used this to destroy certain blocks when the player would shoot them so many times, just switch them to the 3D Collider and Trigger, but it should do the trick for ya (i hope ^^).
edit: this script should be attached to your bullet prefab

Ok so I figured it out, it's kind of weird but apparently I was making the bullets move too fast... I had to slow down the "Bullet_Forward_Force" float to about 150f to make it work. Thanks to everyone who answered though.

I can't comment so I will make an answer:
You can make the bullet go fast, just set the collision detection to continious dynamic.
It has an almost %100 success rate.