Decent lightmapper preview?

Unity Engine
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1

Hi,
the new lightmapper system in Unity 6 it’s somewhat cool and improved some technical shortcomings of the past, but right now the new “preview” system for baking it’s really a step backwards in terms of quality of life and usability. In previous versions I was able to work in realtime, tweaking light intensities and having the changes reflect almost instant feedback in lightmapping, watching a lowres but manageable preview comprised of both direct and indirect lighting. That was awesome. Right now, unless I’m missing something, the only way to get “realtime” lightmapping preview is by switching the viewport to the “lightmapping” debug view and selecting the “preview” render mode. Problem is, I can only see indirect lighting loosing context of the overal scene and hence involving a lot of trial and error to jump from one mode to another, do a bake, wait etc.

Is there a way in current Unity 6 to overcome this issue?

Ps: sorry for selecting the “2d sprites” category for the post, but this new forum style is giving issues on my browser, menu items keep disappearing after one millisecond so for me it’s impossible to choose the right options

2

This. By messing a round with internal values (m_SceneView.camera.useInteractiveLightBakingData) I can view render the scene in Textured mode with the preview lightmap, but it can only get generated and updated when in Debug lighting modes.

(To modify the value of useInteractiveLightBakingData I used 0Harmony)

EDIT: If a secondary SceneView is opened and set to lightmap debug mode and previewing lightmaps, even if that scene is not in focus, the preview lightmap will get generated.

EDIT 2:
I made this small tool that, while not perfect, helps with it. Click on “Tools/Lightmap preview mode” to open a temporary window. While it’s open, the scene view will show the interactive preview light baking. It does not update lightprobes. When done, close the window.
This window opens another SceneView window, it’s a hack so that the lightmapper does it’s thing, otherwise does nothing. It works even if it the window is not visible.

Code (also saved here Lightmap Preview Mode in final render instead of using debug mode. · GitHub)

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

public class LightmapPreviewModeWindow : EditorWindow {
	[MenuItem("Tools/Lightmap preview mode")]
	public static void Get() {
		GetWindow<LightmapPreviewModeWindow>().Show();
	}

	[InitializeOnLoadMethod]
	static void Init() {
		var s_ShowInteractiveLightBakingToggleCameraModes = typeof(SceneView).GetField("s_ShowInteractiveLightBakingToggleCameraModes", BindingFlags.NonPublic | BindingFlags.Static);
		(s_ShowInteractiveLightBakingToggleCameraModes.GetValue(null) as HashSet<DrawCameraMode>).Add(DrawCameraMode.Textured);
	}

	SceneView dummySceneInDebugMode;
	SceneView lastScene;

	void OnEnable2() {
		bool thisHasFocus = this.hasFocus;
		dummySceneInDebugMode = CreateWindow<SceneView>("Ignore", typeof(LightmapPreviewModeWindow));
		dummySceneInDebugMode.cameraMode = SceneView.GetBuiltinCameraMode(DrawCameraMode.BakedLightmap);
		dummySceneInDebugMode.debugDrawModesUseInteractiveLightBakingData = true;
		dummySceneInDebugMode.wantsLessLayoutEvents = true;
		if (thisHasFocus) {
			ShowTab();
		}
		lastScene = SceneView.lastActiveSceneView;
	}

	void OnDisable() {
		dummySceneInDebugMode?.Close();
		if (lastScene != null) lastScene.debugDrawModesUseInteractiveLightBakingData = false;
	}

	void OnGUI() {
		if (dummySceneInDebugMode == null) {
			OnEnable2();
			return;
		}
		GUILayout.Label("Lightmap preview mode", EditorStyles.boldLabel);
		EditorGUILayout.HelpBox("Real time lightmap preview to configure lights quickly", MessageType.Info);
		EditorGUILayout.HelpBox("Doesn't update Lightprobes", MessageType.Warning);
		EditorGUILayout.HelpBox("Close this window when done", MessageType.Info);
		var scene = SceneView.lastActiveSceneView;
		if (scene != lastScene) {
			if (lastScene != null) lastScene.debugDrawModesUseInteractiveLightBakingData = false;
		}
	}

	void Update() {
		lastScene = SceneView.lastActiveSceneView;
		if (lastScene != null) {
			lastScene.debugDrawModesUseInteractiveLightBakingData = true;
			var sceneCam = lastScene.camera;
			dummySceneInDebugMode.camera.transform.SetPositionAndRotation(sceneCam.transform.position, sceneCam.transform.rotation);
			dummySceneInDebugMode.camera.fieldOfView = sceneCam.fieldOfView;
		}
	}
}