Feature Request Prefab Level Generation - Light Probe Support

Levitas · Nov 3, 2020

TLDR: We need LightProbes.positions to not be read only.

We have a procedurally generated map (via rooms) and we want to take our game to the next level by baking lighting in those rooms. I figured out how to bake light maps and change them at runtime, but the only thing stopping us from moving forward is Light Probes. Light Probes can not be moved at run time, the code seems to be buried and hidden, directly from serialization. No way to change or recreate them.

I have been searching for a solution to this problem for weeks and I am really hoping to draw a bit of attention here, because at this moment, there are no tools, no source code, no work arounds that I can find for this problem, and I'm seeing a lot of people stuck in the same situation as me.

This presentation from The Elder Scrolls: Blades shows their solution to this exact problem. It is very nice, but from the looks of it they basically had to rewrite the lighting system. If I could, If I even knew where to begin, I would happily do the same. Are there any classes I can take? I feel the subject is too broad to be self-taught.

Unless I can get help, my current and only course of action is to rewrite the light probe system, and I'm not sure if I can do it alone.

Thank you for your time!

Extrys · Nov 9, 2020

yes please

funkyCoty · Nov 11, 2020

a good place to start learning is to just go to the Unity download archives and download the source code for the builtin shaders. just browse around, search for anything light probe related. skim through stuff like the ShadeSH9 macro.

Extrys · Nov 12, 2020

I meant, to add the light probes in a procedural way, so we can add new proves via code and change their positions and so

thefranke · Dec 1, 2020

Hey Levitas,

can you describe the way you procedurally generate your levels in a bit more detail? Are those spawned at regular positions? I.e. is this some kind of grid where you add rooms to other rooms at fixed positions?

Cheers

Doodel · Dec 16, 2020

I just necroed a thread from 2012 in the general support forum (sorry for that) that asked the same question but is better placed here i guess.

In the thread robert from Unity gives an answer to why Lightprobes.positions is read-only.:

robert said: ↑

LightProbes.positions is read-only, because changing the relative positions of probes requires re-tessellating the space with tetrahedra and re-generating all the data associated with it. For now that code is editor-only, so you can't use it at runtime. Also it takes some time to do that, so for larger probe sets it would have to be done asynchronously.
Click to expand...

In Unity 2019.3 these missing functions were finally added: LightProbes.Tetrahedralize and LightProbes.TetrahedralizeAsync

So now it seems there is a way to recalculate the lightprobe data in runtime but Lightprobes.positions is still read-only. Is this just an oversight or am I missing something here?

Levitas · Jan 30, 2021

thefranke said: ↑

Hey Levitas,

can you describe the way you procedurally generate your levels in a bit more detail? Are those spawned at regular positions? I.e. is this some kind of grid where you add rooms to other rooms at fixed positions?

Cheers
Click to expand...

As I understand it, I can load a set of light probes at run time and Tetrahedralize them, but I have to know where those light probes are going to be in world space beforehand.
This won't work for us since we instantiate our room prefabs to create a random maze, so to speak.
We need a way to save the light probes per prefab and convert from local to world space after level gen.

thefranke · Feb 1, 2021

Levitas said: ↑

As I understand it, I can load a set of light probes at run time and Tetrahedralize them, but I have to know where those light probes are going to be in world space beforehand.
This won't work for us since we instantiate our room prefabs to create a random maze, so to speak.
We need a way to save the light probes per prefab and convert from local to world space after level gen.
Click to expand...

So, in relation to the geometry around them, probes are fixed in the prefabs and have fixed lighting, it's just that you want to instantiate those blocks of geometry to build the level, correct? I.e. each room is a kind of a closed lighting system?

The probe system never allowed for modification after baking. I recently changed that so you one can at least additively load probes with the re-tetrahedralization feature, but I think we can loosen that restriction even further for prefabs. I got this noted in the probe backlog, but unfortunately I have no solution right now you could use.

Levitas · Feb 7, 2021

thefranke said: ↑

So, in relation to the geometry around them, probes are fixed in the prefabs and have fixed lighting, it's just that you want to instantiate those blocks of geometry to build the level, correct? I.e. each room is a kind of a closed lighting system?

The probe system never allowed for modification after baking. I recently changed that so you one can at least additively load probes with the re-tetrahedralization feature, but I think we can loosen that restriction even further for prefabs. I got this noted in the probe backlog, but unfortunately I have no solution right now you could use.
Click to expand...

This is exactly what we need. Thank you very much for your time and effort here, it is greatly appreciated. We patiently wait for such an update.

Extrys · Feb 8, 2021

thefranke said: ↑

So, in relation to the geometry around them, probes are fixed in the prefabs and have fixed lighting, it's just that you want to instantiate those blocks of geometry to build the level, correct? I.e. each room is a kind of a closed lighting system?

The probe system never allowed for modification after baking. I recently changed that so you one can at least additively load probes with the re-tetrahedralization feature, but I think we can loosen that restriction even further for prefabs. I got this noted in the probe backlog, but unfortunately I have no solution right now you could use.
Click to expand...

yeah, the exact thing available to do with additive scene loading would be amazing with prefabs.

Anyways being able to change the positions so they are not readonly would make it easier to build our own procedural additive light probes
and even creating a dots powered version for runtime baking

Currently, if I want to do a transition between different backed light prove groups I'm restricted to change only the Spherical Harmonics and blend between them, but I can not do that with the positions nor creating my own randomizer for procedurally generated bake data

Probably an option would be making the light probe data being stored inside the LightproveGroup component instead of the Scene, so switching between different backed light proveGroups components/prefabs could be a solution

Daniel_Nagy · Feb 19, 2021

+1 for this, it would make workflow much easier!

DGordon · Feb 21, 2021

Anything to make GI + randomization not require lots of in depth knowledge or time trying to get it to work ... gets a huge +1 from me .

MicCode · Feb 24, 2021

+1 to runtime modification of light probe

l33t_P4j33t · Mar 15, 2021

if you are PROgrammer, you can do AssetBundle.LoadFromMemory(bytes[]) on a runtime generated asset bundle that has your desired light probe layout

TheZombieKiller said: ↑

You can modify LightProbes.positions using a SerializedObject in the editor, but that's not available at runtime.

The LightProbe API is annoyingly limited at runtime, especially so when you know that you can construct an AssetBundle in memory to get around it (a similar issue applies to the Font class, and I've used the same technique to get around it before).

The problem with that approach though is that you need to have knowledge of the file format and you need to know how to construct one correctly for your particular Unity version.
Click to expand...

Aurigan · Mar 16, 2021

Another +1 for some way to use light probes in proc-gen layouts!

apkdev · Sep 20, 2021

My project needs this API too. Is there a technical reason why implementing this has been postponed for so long? Is the laughably scuffed Asset Bundle workaround really what I'll have to resort to?

geonegames · Jan 24, 2022

+1. Without the ability to change light probe positions at runtime, it's infeasible to use baked lighting in procedural games unless you're willing to effectively create your own implementation of light probes.

Support for light probe groups in prefabs would be a magnificent addition.

Extrys · Jan 24, 2022

geonegames said: ↑

+1. Without the ability to change light probe positions at runtime, it's infeasible to use baked lighting in procedural games unless you're willing to effectively create your own implementation of light probes.

Support for light probe groups in prefabs would be a magnificent addition.
Click to expand...

You actually can, you just need to copy the whole light probe data of the scene, modify the position of the copied data, and then re apply that data as the current light probe data

apkdev · Jan 24, 2022

Extrys said: ↑

You actually can, you just need to copy the whole light probe data of the scene, modify the position of the copied data, and then re apply that data as the current light probe data
Click to expand...

RPGia · Feb 27, 2022

Aurigan said: ↑

Another +1 for some way to use light probes in proc-gen layouts!
Click to expand...

+1

RPGia · Sep 17, 2022

bump

emrys90 · Nov 5, 2022

Any news on this?

RPGia · Nov 24, 2022

bump

RPGia · Jan 25, 2023

Bump

Pema-Malling · Mar 30, 2023

Hey everyone, I’d like to point out a few release notes from the recent 2023.2.0a8 release, which should be useful to several of the users in this thread:

> Graphics: Add API for modifying positions of LightProbes objects.
> GI: Add API for accessing global light probe data used in rendering as well as for individual scenes.

Essentially, we’ve added an API which allows moving light probes at runtime at the granularity of individual probe positions. Below is an example snippet from the documentation showing how to additively load a scene and move the probes associated with it. We’d like to expand a bit upon the API in the future, but it should cover most of the use cases we identified in its current state.

Code (CSharp):

using System.Collections;

using UnityEngine;

using UnityEngine.SceneManagement;

public class MoveLightProbesExample : MonoBehaviour

{

void Start()

{

StartCoroutine(LoadSceneAndMoveLightProbes());

}

IEnumerator LoadSceneAndMoveLightProbes()

{

// Fully load a scene containing light probes additively.

Scene additiveScene = SceneManager.LoadScene("AdditiveScene", new LoadSceneParameters(LoadSceneMode.Additive));

yield return null;

// Get the light probes for the scene.

LightProbes lightProbes = LightProbes.GetInstantiatedLightProbesForScene(additiveScene);

// Move the light probes slightly.

Vector3[] positions = lightProbes.GetPositionsSelf();

for (int i = 0; i < positions.Length; i++)

{

positions[i] += Vector3.one;

}

lightProbes.SetPositionsSelf(positions, true);

// Tetrahedralize to apply the changes to light probe positions.

LightProbes.TetrahedralizeAsync();

}

}

Looking forward to seeing how this will be used If you encounter issues, please use the bug reporter instead of posting here - it is much faster for us to notice and fix issues that way. I can answer questions about the API here, though.

RPGia · Apr 18, 2023

Pema-Malling said: ↑

Hey everyone, I’d like to point out a few release notes from the recent 2023.2.0a8 release, which should be useful to several of the users in this thread:

> Graphics: Add API for modifying positions of LightProbes objects.
> GI: Add API for accessing global light probe data used in rendering as well as for individual scenes.

Essentially, we’ve added an API which allows moving light probes at runtime at the granularity of individual probe positions. Below is an example snippet from the documentation showing how to additively load a scene and move the probes associated with it. We’d like to expand a bit upon the API in the future, but it should cover most of the use cases we identified in its current state.

Code (CSharp):

using System.Collections;

using UnityEngine;

using UnityEngine.SceneManagement;

public class MoveLightProbesExample : MonoBehaviour

{

void Start()

{

StartCoroutine(LoadSceneAndMoveLightProbes());

}

IEnumerator LoadSceneAndMoveLightProbes()

{

// Fully load a scene containing light probes additively.

Scene additiveScene = SceneManager.LoadScene("AdditiveScene", new LoadSceneParameters(LoadSceneMode.Additive));

yield return null;

// Get the light probes for the scene.

LightProbes lightProbes = LightProbes.GetInstantiatedLightProbesForScene(additiveScene);

// Move the light probes slightly.

Vector3[] positions = lightProbes.GetPositionsSelf();

for (int i = 0; i < positions.Length; i++)

{

positions[i] += Vector3.one;

}

lightProbes.SetPositionsSelf(positions, true);

// Tetrahedralize to apply the changes to light probe positions.

LightProbes.TetrahedralizeAsync();

}

}

Looking forward to seeing how this will be used If you encounter issues, please use the bug reporter instead of posting here - it is much faster for us to notice and fix issues that way. I can answer questions about the API here, though.
Click to expand...

Hello, thank you for this update.

What about the issue reported at:

https://forum.unity.com/threads/lighting-data-asset-was-a-mistake.547591/#post-8936436

TheZombieKiller · Apr 19, 2023

Would it be possible for there to be an additional API for resizing the positions array within the LightProbes object? I was very excited to see these APIs mentioned in the changelog but then found that I'm still not able to use light probes for runtime-generated scenes because I cannot resize the array

The only workaround I know of is to pre-fill a blank "template" scene with a large number of dummy probes and then modify them at runtime, but that naturally comes with many limitations and can't cover multi-scene use cases.

Other than this though, the APIs are great! It's a much-appreciated step forward for the lighting functionality available at runtime.

Pema-Malling · Apr 19, 2023

@TheZombieKiller Hey there. Thanks for the feedback, and for pointing out that your use case isn't sufficiently supported. I'll try to pick to my words carefully in this response, since I don't want to make any false promises. The use case you pointed it out is one of a few which we identified while working on the API, but decided not to support in the first iteration of it, instead focusing on the use case of piecing together pre-baked scenes at runtime. In other words, it is something we have tracked internally, but I can't give you an ETA, other than saying it is probably unlikely for 2023.1 or 2023.2.

Pema-Malling · Apr 19, 2023

To give a bit more context, the primary issue with this use case is that a LightProbes object currently stores data from an arbitrary amount of scenes, with an arbitrary amount of probe groups. This makes the meaning of resizing the data a bit ambiguous, and would invalidate some unexposed per-probe-group data, which we'd like to keep unexposed, since it's likely to change. That change would be breaking, though, and would affect our ability to be backwards compatible with existing light probe API, as well as the functionality of Enlighten RTGI.

TheZombieKiller · Apr 19, 2023

That makes much more sense and explains why the API is limited in the way it currently is, thanks! Just knowing that it's being tracked internally is good enough for me

RPGia · Apr 20, 2023

TheZombieKiller said: ↑

The only workaround I know of is to pre-fill a blank "template" scene with a large number of dummy probes and then modify them at runtime, but that naturally comes with many limitations and can't cover multi-scene use cases..
Click to expand...

So are you going with this solution? I'm interested in this. It sounds like you have to use lightmapped prefabs, and not lightmapped additive scenes with this method?

TheZombieKiller · Apr 20, 2023

RPGia said: ↑

So are you going with this solution? I'm interested in this. It sounds like you have to use lightmapped prefabs, and not lightmapped additive scenes with this method?
Click to expand...

Right now what we do is use
MaterialPropertyBlock.CopySHCoefficientArraysFrom
to assign probe lighting via our own system, rather than using the built-in light probe system. It has lots of caveats though (an example being incompatibility with the SRP batcher) which is why it'd be preferable to use the built-in light probe system if possible, but the template scene workaround isn't good enough for our use cases.

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Feature Request Prefab Level Generation - Light Probe Support

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DGordon

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Feature Request Prefab Level Generation - Light Probe Support

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