Hello how are you?
I need help getting a collision of a GameObject.
That is, I created an Empty GameObject in my scene with the following script:
Public GameObject test_Plate;
void OnCollisionEnter (Collision col) {
//I need info collision test_Plate
}
What I need, is to have no script in me Object(test_Plate) in Scena
I use C#.
Wait answers!!! Hug <3
You can find the information of a collision from the parameter you named “col”. Read about what’s in it
But the parameter col name. Does not look for the information from the object to insert the script?
I need information from another object parallel to my empty object
OnCollisionEnter works with a collider to know what the object has collided with. At least one of the two objects need a rigidbody for the collision to register. It cannot establish communications between 2 object which will never meet. Since you say you are using an empty object, OnCollisionEnter will never fire off. It will be better if you state what you are trying to do.
ok, I understand. It is impossible to do what I thought.
So, how do I create an empty object manager, where does my scene work? I need to create buttons and perform actions (it is a puzzle game).
How do I create many buttons that produce different actions each one, when the button is pressed?
What should I use? Can you show me examples?
When I read this I read it as the Empty Object never intending to hit the test plate. but instead it wants to know when anything else hits the plate.
what you can do is write a monobehaviour that has a public event (personally I’m used to using UnityEvents) and an OnCollisionEnter. when Unity messages the OncollisionEnter, inside you pass off the collision data through the public event. finally at runtime your empty object can add this class to the testplate via AddComponent, then subscribe to the event, and listen when anything hits that test plate. finally be sure to clean up your events when the empty object is disabled (so you don’t have orphaned handlers) or if you change the test plate reference.
Yess exactly, is thiss
Ohh okkkk, I understand, I can create an OnCollisionEnter in my empty object script and from there add the component to “test_plate” and almost get information from when they step on it.
Can you give me code examples? I’m pretty new at programming.
My final goal is to create manys buttons and when I step on them with my “player” do something.
Thx broo, hugg!
I have the code here. but as an exercise to better yourself try and see what you can come up with first before looking at it. It should also help you understand what I’ve done in my code and why I’ve done it.
First as a disclaimer, I wrote this code to use Collisions. however in your specific use case I would have more likely used Triggers, and have trigger volumes over plates where entities would stand. Triggers would have more consistent enter/exit states, plus from the sounds of it you don’t really need all that collision data that comes inside a Collision object. However Triggers vs Collisions doesn’t change the code too much so I continued with Collisions. you can make it a personal exercise to convert it to using triggers.
Code
The code I’ve provided is a stub, so on its own it won’t do much (at all). There are several different ways you can set this up, personally I prefer to write my code so that it exploits the Inspector as much as possible, as you can see with the code I wrote.
public class CollisionEvent: UnityEngine.Events.UnityEvent<GameObject,Collision>{}
public class CollisionDispatcher: MonoBehaviour
{
public CollisionEvent OnCollisionEntered;
public CollisionEvent OnCollisionUpdated;
public CollisionEvent OnCollisionExiteded;
private OnCollisionEnter(Collision col)
{
OnCollisionEntered.Invoke(gameObject,col);
}
private OnCollisionStay(Collision col)
{
OnCollisionUpdated.Invoke(gameObject,col);
}
private OnCollisionExit(Collision col)
{
OnCollisionExited.Invoke(gameObject,col);
}
}
public class CollisionListener: MonoBehaviour
{
[serializeField] private Gameobject m_collidee;
private GameObject m_lastValidatedCollidee;
public GameObject Collidee
{
get{return m_collidee;}
set
{
if(m_collidee == value) return;
RemoveDispatcher(m_collidee);
AddDispatcher(value);
m_collidee = value;
m_lastValidatedCollidee = value;
}
}
}
private void OnEnable()
{
AddDispatcher(m_collidee);
}
private void OnDisable()
{
RemoveDispatcher(m_collidee);
}
private void OnValidate()
{
#if UNITY_EDITOR
if(!UnityEditor.EditorApplication.isPlaying)
return;
#endif
if(m_collidee == m_lastValidatedCollidee)
return;
RemoveDispatcher(m_lastValidatedCollidee);
AddDispatcher(m_collidee);
m_lastValidatedCollidee = m_collidee;
]
private void AddDispatcher(GameObject target)
{
if(!target) return;
var dispatcher = target.GetComponent<CollisionDispatcher>();
if(!dispatcher)
dispatcher = target.AddComponent<CollisionDispatcher>();
dispatcher.OnCollisionEntered.AddListener(WhenCollisionEnters);
dispatcher.OnCollisionUpdated.AddListener(WhenCollisionUpdates);
dispatcher.OnCollisionExiteded.AddListener(WhenCollisionExits);
}
private void RemoveDispatcher(GameObject target)
{
if(!target) return;
var dispatcher = target.GetComponent<CollisionDispatcher>();
if(! dispatcher) return;
dispatcher.OnCollisionEntered.RemoveListener(WhenCollisionEnters);
dispatcher.OnCollisionUpdated.RemoveListener(WhenCollisionUpdates);
dispatcher.OnCollisionExiteded.RemoveListener(WhenCollisionExits);
//don't remove the dispatcher from the target, some other class might be needing it.
// we just don't need to be listening to it.
}
private void WhenCollisionEnters(GameObject target, Collision collision)
{
// stuff to do when target enters a contact
}
private void WhenCollisionUpdates(GameObject target, Collision collision)
{
// stuff to do while target stays in contact
}
private void WhenCollisionExits(GameObject target, Collision collision)
{
// stuff to do when target leaves contact
}
Since you’re a beginner there are likely several things in the code which you may not understand. For me I didn’t hold back to make it easier for a beginner to read, I simply wrote it how I would like to use it.
Luckily this is the internet so information on Unity API, C#, Properties vs fields, Events, and even design patterns can all be easily found. It just takes practice and study. Plus you can always ask directly in the forums, but before you do try and search if your question has already been answered, you’ll typically find a solution faster that way.