How can I check if a GameObject contain a meshrenderer but not contain any collider and then add a collider to it?

3
votes
using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class AddColliders : MonoBehaviour
{
    public List<GameObject> objectsToAddCollider = new List<GameObject>();

    // Start is called before the first frame update
    void Start()
    {
        AddDescendantsWithTag(transform, objectsToAddCollider);
    }

    // Update is called once per frame
    void Update()
    {

    }

    private void AddDescendantsWithTag(Transform parent, List<GameObject> list)
    {
        foreach (Transform child in parent)
        {
            if (child.gameObject.GetComponent<MeshRenderer>() != null
                && child.gameObject.GetComponent<)
            {
                list.Add(child.gameObject);
            }
            AddDescendantsWithTag(child, list);
        }
    }
}

At this line I'm checking that there is a mesh renderer attached to the gameobject but how do I check if it don't have attached any collider type ? And then how to add a mesh collider to it ?

This is what I tried so far :

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class AddColliders : MonoBehaviour
{
    public List<GameObject> objectsToAddCollider = new List<GameObject>();

    // Start is called before the first frame update
    void Start()
    {
        AddDescendantsWithTag(transform, objectsToAddCollider);
    }

    // Update is called once per frame
    void Update()
    {

    }

    private void AddDescendantsWithTag(Transform parent, List<GameObject> list)
    {
        foreach (Transform child in parent)
        {
            if (child.gameObject.GetComponent<MeshRenderer>() != null
                && child.gameObject.GetComponent<Collider>() == null)
            {
                child.gameObject.AddComponent<MeshCollider>();
                list.Add(child.gameObject);
            }
            AddDescendantsWithTag(child, list);
        }
    }
}

But then in the end when adding a break point on the line :

AddDescendantsWithTag(transform, objectsToAddCollider);

I see that the gameobjects in the List objectsToAddCollider in the Collider this message :

collider = System.NotSupportedException: collider property has been deprecated

Collider

2
c#unity3d

2 Answers

5
votes

GameObject.collider was deprecated and removed in version 2019.1.0.

You can't use it for debugging anymore.

To check if there is a Collider of any type use

var collider = child.GetComponent<Collider>();

to simply check if it exists you could also do

if(child.GetComponent<Collider>())
{
    Debug.Log("Collider found");
}

again since Collider (or better said Unity's type Object from which it inherits) implements an implicit bool operator which equals != null.

A very nice way to add the component if it does not exist in a single line is therefore

Collider collider = child.GetComponent<Collider>() ? collider : child.gameObject.AddComponent<Collider>();

or even slightly shorter

Collider collider = child.GetComponent<Collider>() ?? child.gameObject.AddComponent<Collider>();

Note: Typed on smartphone so no warranty but I hope the idea gets clear.

2
votes

You can use Collider as it is the base class for all colliders. 

    private void AddDescendantsWithTag(Transform parent, List<GameObject> list)
{
    foreach (Transform child in parent)
    {
        if (child.gameObject.GetComponent<MeshRenderer>() != null
            && child.gameObject.GetComponent<Collider>()) // You can modify this line according to your requirement. 
        {
            list.Add(child.gameObject);
        }
        AddDescendantsWithTag(child, list);
    }
}