PostProcessingScene work - a way to temporarily modify scenes at build time

PostProcessingSceneUtilities.cs

using UnityEngine;
using UnityEditor;
using UnityEditor.Callbacks;
using System.Collections.Generic;

// @kurtdekker
//
// Makes temporary changes to scenes when building.
//
// Obviously this must live in an Editor/ folder.

public static class PostProcessingSceneUtilities
{
	[PostProcessSceneAttribute (2)]
	public static void OnPostprocessScene()
	{
		RemoveStaticFlagsHelper( complain: false);
	}

	[MenuItem( "Assets/Remove Static Flags")]
	static void RemoveStaticFlags()
	{
		RemoveStaticFlagsHelper( complain: true);
	}

	static void RemoveStaticFlagsHelper( bool complain = false)
	{
		var ToChange = new List<GameObject>();

		var trs = GameObject.FindObjectsOfType<Transform>();

		if (complain)
		{
			Debug.Log( "trs.Length = " + trs.Length);
		}

		foreach( var tr in trs)
		{
			var go = tr.gameObject;

			if (go.isStatic)
			{
				ToChange.Add( go);
			}
		}

		var ToChangeArray = ToChange.ToArray();

		if (ToChangeArray.Length > 0)
		{
			if (complain)
			{
				Debug.Log( System.String.Format(
					"Removing {0} static flags.", ToChangeArray.Length));
			}
		}
		else
		{
			if (complain)
			{
				Debug.LogWarning( "No objects marked static found!");
			}
		}

		Undo.RecordObjects( ToChangeArray, "Remove Static");

		// actual doing the work here...

		foreach( var go in ToChangeArray)
		{
			// I used to do this, but this means it cannot be used in
			// games that use Unity navigation:
//			go.isStatic = false;

			// the point of this whole thing is only to remove lightmap
			// static flags, so let's just do that!
			var flags = GameObjectUtility.GetStaticEditorFlags( go);
#if UNITY_2020_1_OR_NEWER
			flags &= ~(StaticEditorFlags.ContributeGI);
#else
			flags &= ~(StaticEditorFlags.LightmapStatic);
#endif
			GameObjectUtility.SetStaticEditorFlags( go, flags);
		}
	}
}