AssetDatabase.IsMainAsset

Проверяет, является ли ассет основным ассетом в окне Project.

Например, у импортированной модели есть корневой GameObject и несколько мешей и дочерних GameObject в развёрнутом состоянии. Корневой GameObject в этом случае — основной ассет.

using UnityEditor;
using UnityEngine;

public class Scriptable : ScriptableObject
{
}

public class AssetDatabaseExamples : MonoBehaviour
{
    [MenuItem("AssetDatabase/Is Main Asset Example")]
    static void IsMainAssetExample()
    {
        var materialAsset = new Material(Shader.Find("Standard"));

        //materialAsset is still in memory, therefore this will be False
        Debug.Log(AssetDatabase.IsMainAsset(materialAsset));

        //Create a Scriptable object
        var scriptableAssetPath = "Assets/ScriptableObjects/NewObject.asset";
        var mainAsset = ScriptableObject.CreateInstance<Scriptable>();
        AssetDatabase.CreateAsset(mainAsset, scriptableAssetPath);

        //Add the Material Asset to the Scriptable object, so that the Material becomes a Sub Asset of the Scriptable object
        AssetDatabase.AddObjectToAsset(materialAsset, scriptableAssetPath);
        AssetDatabase.SaveAssets();

        //This will be false because material asset has been added to the main Asset and is now a Sub Asset
        Debug.Log(AssetDatabase.IsMainAsset(materialAsset));

        //Remove the subAsset from the Scriptable object and create it as an Asset
        AssetDatabase.RemoveObjectFromAsset(materialAsset);
        AssetDatabase.CreateAsset(materialAsset, "Assets/Materials/New Mat0.mat");

        //This will be True because the material is now the main Asset
        Debug.Log(AssetDatabase.IsMainAsset(materialAsset));
    }
}