Htykuut

I'm a total newcomer to unity and I was just wondering how to set a material from C#?

I have a prefab model and I can change the texture from the editor no problem. What I want to do is randomly set the material when an instance of the prefab is generated.

Here is the field I want to change:

And I am creating these with the following code:

Instantiate(eggPrefab, spawnPos, Quaternion.identity);

(Where eggPrefab is a public Transform).

I hope that is enough information!

Thank you.

I think mixing the random material behaviour with creation behaviour is overcomplicating things. Just create a component that randomises a GameObject's material on Start and it will run when you instantiate your prefab.

public class MaterialRandomiser : MonoBehaviour {



  [SerializeField]

  private Material _materials;

  [SerializeField]

  private Renderer _renderer;



  public void Start () {

    ChangeMaterial();

  }



  public void Reset () {

    _renderer = GetComponent<Renderer>();

  }



  public void ChangeMaterial () {

    _renderer.material = SelectRandomMaterial();

  }



  private Material SelectRandomMaterial () {

    return _materials[Random.Range(0, _materials.Length)];

  }



}

Attach it to your prefab and now when you spawn them, they will have random materials. You now also have the option to use the same code on non-prefab objects as well. Just don't forget to assign the materials!

After you instantiate the GameObject, get the MeshRenderer from it then change it's material:

public GameObject eggPrefab;

public Vector3 spawnPos;

public Material mat;



void Start()

{

    GameObject obj = Instantiate(eggPrefab, spawnPos, Quaternion.identity);

    obj.GetComponent<MeshRenderer>().material = mat;

}

If you don't have the material then you can create one with a shader and assign it to the MeshRenderer:

GameObject obj = Instantiate(eggPrefab, spawnPos, Quaternion.identity);



//Find the Standard Shader

Material mat = new Material(Shader.Find("Standard"));

//Set Texture on the material

//mat.SetTexture("_MainTex", yourTexture);



obj.GetComponent<MeshRenderer>().material = mat;

Finally, if you have more than one material then use the materials property instead of the material property and assign your array of material to it:

GameObject obj = Instantiate(eggPrefab, spawnPos, Quaternion.identity);



//Find the Standard Shader

Material mat = new Material(Shader.Find("Standard"));

//Set Texture on the material

//mat.SetTexture("_MainTex", yourTexture);



//Create array of mats (Create one for example)

Material mats = new Material[1];

mats[0] = mat;



obj.GetComponent<MeshRenderer>().materials = mats;

Edit:

I missed the random part. If you want random material selection, just use Random.Range to select one item from the array of Material.

public GameObject eggPrefab;

public Vector3 spawnPos;

public Material mats;



void Start()

{

    GameObject obj = Instantiate(eggPrefab, spawnPos, Quaternion.identity);

    int matIndex = UnityEngine.Random.Range(0, mats.Length);

    obj.GetComponent<MeshRenderer>().material = mats[matIndex];

}

You could do the following using an materials array.

    public Material materialsArray;

    public GameObject prefab;

    private Vector3 pos = new Vector3(0, 0, 0);

    private Quaternion rot = Quaternion.identity;



    private void Start()

    {

        Material mat = RandomMaterial(materialsArray);

        InstantiateWithMaterial(prefab, pos, rot, mat);

    }



    public Material RandomMaterial(Material _array_)

    {

        return _array_[Random.Range(0, _array_.Length)];

    }



    public void InstantiateWithMaterial(GameObject _prefab_, Vector3 _pos_, Quaternion _rot_, Material _mat_)

    {

        GameObject obj_ = Instantiate(_prefab_, _pos_, _rot_);

        obj_.gameObject.GetComponent<MeshRenderer>().material = _mat_;

    }

This should work how you want, just place on an empty GameObject and populate the materials array with all the materials you want.