ObstaclePlaceholder.cs

using Sirenix.OdinInspector;
using UnityEngine;
#if UNITY_EDITOR
#endif

/// <summary>
/// Placed where an obstacle will be spawned when the game loads.
/// Used to fake nested prefabs in a pre-2018.3 world.
/// </summary>
[ExecuteInEditMode]
[SelectionBase]
public class ObstaclePlaceholder : MonoBehaviour
{
	/// <summary>
	/// The obstacle that will be used for this placeholder.
	/// </summary>
	[ValueDropdown("DropdownValuesFunction")]
	public GameObject Obstacle;

	/// <summary>
	/// Odin Inspector doesn't let us use ValueDropdown on the same field as
	/// InlineEditor... so we use this workaround so we can still show the preview
	/// without sacrificing the dropdown box.
	/// </summary>
	[InlineEditor(InlineEditorModes.LargePreview)]
	[ShowInInspector]
	[HideLabel]
	public GameObject ObstacleForPreview => Obstacle;

	private GameObject previewObject;
	private GameObject previewSource;

	/// <summary>
	/// Passes through DropdownValuesFunction from ObstacleTypes
	/// for use with OdinInspector.
	/// </summary>
	public ValueDropdownList<GameObject> DropdownValuesFunction() =>
		ObstacleTypes.DropdownValuesFunction();

	/// <summary>
	/// The object that's currently being used for the preview.
	/// </summary>
	public GameObject PreviewObject => previewObject;

	// all this code deals with displaying the preview
	// so we only need to include it in the editor
#if UNITY_EDITOR
	private void Update()
	{
		// if we're playing, destroy any preview objects if any still exist
		if(Application.isPlaying)
		{
			if(previewObject != null)
			{
				DestroyImmediate(previewObject);
			}

			return;
		}

		// if the obstacle changed since last frame, replace the current preview
		if(
			Obstacle != null &&
			(previewObject == null || previewSource != Obstacle))
		{
			// destroy if necessary
			if(previewObject != null)
			{
				DestroyImmediate(previewObject);
			}

			// create preview object
			// we create an empty object for the parent to apply the hideflags to because HideFlags.HideInHierarchy
			// also implicitly makes it unselectable, and we want them to be selectable
			previewObject = new GameObject("Preview Parent");
			previewObject.transform.parent = transform;
			previewObject.transform.localScale = Vector3.one;
			previewObject.transform.localPosition = Vector3.zero;
			previewObject.hideFlags = HideFlags.HideAndDontSave;
			previewSource = Obstacle;

			var obs = Instantiate(Obstacle, previewObject.transform);
			obs.transform.localPosition = Vector3.zero;
			obs.hideFlags = HideFlags.HideInInspector;

			// apply hideflags to children
			foreach(var t in obs.GetComponentsInChildren<Transform>())
			{
				t.gameObject.hideFlags = obs.hideFlags;
			}
		}
	}
#endif
}