PrefabToIcon

PrefabToIcon.cs

using UnityEngine;

public class PrefabToIcon
{
    private float _distanceThreshold;

    private readonly int _iconWidth = 512;
    private readonly int _iconHeight = 512;

    private readonly Vector3 _scale = new Vector3(1, 1, 1);
    private readonly Quaternion _rotation = Quaternion.Euler(new(345.8529f, -30f, 14.28433f));

    private Camera _camera;
    private LayerMask _layerMask;
    private RenderTexture _prevRenderTexture;

    private int _LayerMaskToLayer(LayerMask mask) => (int)Mathf.Log(mask.value, 2);

    private void _SetLayerRecursively(GameObject gameObject, LayerMask targetLayer)
    {
        gameObject.layer = _LayerMaskToLayer(targetLayer);

        foreach (Transform child in gameObject.transform)
        {
            _SetLayerRecursively(child.gameObject, targetLayer);
        }
    }

    private GameObject _CreatePrefabClone(ref GameObject prefab)
    {
        var cameraTransform = _camera.transform;
        var prefabClone = Object.Instantiate(prefab);
        prefabClone.transform.position = cameraTransform.position + (cameraTransform.forward * _distanceThreshold);
        prefabClone.transform.rotation = _rotation;
        prefabClone.transform.localScale = _scale;
        return prefabClone;
    }

    private GameObject _CreateGameObjectWithCamera()
    {
        var cameraGameObject = new GameObject();
        
        _camera = cameraGameObject.AddComponent<Camera>();
        
        return cameraGameObject;
    }

    private void _SetupCamera()
    {
        _camera.cullingMask = _layerMask;
        _camera.clearFlags = CameraClearFlags.SolidColor;
        _camera.nearClipPlane = 0.01f;
        _camera.backgroundColor = Color.gray;
        _camera.targetTexture = RenderTexture.GetTemporary(_iconWidth, _iconHeight, 24);
        _camera.Render(); 
    }

    private Texture2D _CreateTexture2DOfPrefab()
    {
        var targetTexture = _camera.targetTexture;
        RenderTexture.active = targetTexture;

        var iconTexture = new Texture2D(targetTexture.width, targetTexture.height);
        iconTexture.ReadPixels(new Rect(0, 0, targetTexture.width, targetTexture.height), 0, 0);
        iconTexture.Apply();

        return iconTexture;
    }

    private void _ClearSettings(ref GameObject prefabClone, ref GameObject cameraGameObject)
    {
        _camera.clearFlags = CameraClearFlags.Skybox;
        _camera.targetTexture = null;

        RenderTexture.ReleaseTemporary(_camera.targetTexture);

        Object.DestroyImmediate(prefabClone);
        Object.DestroyImmediate(cameraGameObject); 
    }
    
    public Texture2D CreateIconOf(GameObject prefab, LayerMask targetLayer, float distanceThreshold = 1f)
    {
        _distanceThreshold = distanceThreshold;
        _layerMask = targetLayer;
    
        var cameraGameObject = _CreateGameObjectWithCamera();
    
        var prefabClone = _CreatePrefabClone(ref prefab);

        _SetLayerRecursively(prefabClone, targetLayer);
        
        _SetupCamera();
    
        var iconTexture = _CreateTexture2DOfPrefab();
        
        _ClearSettings(ref prefabClone, ref cameraGameObject);
    
        return iconTexture;
    }
}