Lightmaps and shadows, other lighting questions

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Lightmaps and shadows, other lighting questions

marcinn

Hi.

A noob's questions.

Is possible to bake lightmaps with soft shadows for directional light? I'm experimenting with outdoor scenery. There are many trees, so dynamic shadows are too heavy. GIProbe is too heavy, too. I'd like to bake direct and indirect lights, but preserve dynamic shadows for characters. I set baking mode for directional light to "All", but there are no shadows visible. When I turn on shadows for directional light, they're generated dynamically.

I'm using HTerrain plugin. Does baking lightmap works as expected with it? I would like to know if I am doing something wrong, or if there are any limitations. I think that grass is not taking indirect light, that's why it is almost black in shaded areas (see below). I can workaround this by increasing ambient light, but then I'm jumping into another problem - interiors. I have few houses that the player can enter. When I'm increasing ambient light, interiors looks wrong. That's why I'm trying to keep ambient light as low as possible.

EDIT: I forgot to mention, that screens are taken with GIProbe enabled (for testing).

And here is a screen without GIProbe, but with increased ambient lighting:

Shadows are disabled for now.

Kind Regards! Marcin

cybereality

So baked shadows and real-time shadows don't mix right now. It's one or the other. For a game like yours, you probably want to use bake mode indirect and then use standard shadow mapping in real time for direct shadows. If performance is an issue, you can use bake mode all and use a fake blob shadow for the character. Though in a large open world, light baking is less useful as you will have to bake too large an area and deal with seams. So real-time is probably a better idea. If you lower the range and settings of the shadow, it should be fast enough.

Calinou

I'd like to bake direct and indirect lights, but preserve dynamic shadows for characters. I set baking mode for directional light to "All", but there are no shadows visible. When I turn on shadows for directional light, they're generated dynamically.

Having a baked light cast both static and dynamic shadows requires shadowmasking, which is not implemented yet. I have a pull request that implements it for 3.x, but it doesn't support HDR or denoising. It'll likely take a while for this pull request to be in a mergeable state (if ever).

marcinn

I have a pull request that implements it for 3.x, but it doesn't support HDR or denoising. It'll likely take a while for this pull request to be in a mergeable state (if ever).

That's exactly what is missing. I haven't written about it before, but with dynamic shadows the forest in my scene gets brighter as the distance from the camera increases (max distance for shadows is way less than camera's far culling distance)

Meanwhile I found https://github.com/lawnjelly/godot-llightmap, but I haven't tested it yet. Can this help somehow with PR 51330?

cybereality

If you use shadow cascades, you can get pretty good coverage. You won't get the whole world. Even AAA games like Assassin's Creed have a cut-off on the shadow if you look closely. But you can adjust the ranges so that is looks convincing and only the far distance is not shadowed. If you add fog, you can hide this a bit.

Calinou

@marcinn said: Meanwhile I found https://github.com/lawnjelly/godot-llightmap, but I haven't tested it yet. Can this help somehow with PR 51330?

For most use cases, that separate module is no longer useful now that Godot has a CPU lightmapper in core (since Godot 3.3). It also doesn't provide shadowmasking anyway.

marcinn

@cybereality, thanks for all suggestions. At this moment I'd like to know possibilities and limitations of the engine. I wanted to focus on the visual layer, but keeping best performance as possible.

@Calinou I compiled your branch (merged with upstream's 3.x). The solution is promising and I achieved a good performance - up to 20fps full screen FHD in "Always Shadowmask" mode.

However I found some issues / limitations:

Missing property to disable shadow casting of baked meshes. The lack of one switch is getting more painful as LODs number increases (I'm using your plugin / script).
I have trouble lighting the ground, but this may be related to HTerrain plugin itself (it creates terrain chunks dynamically). In my 2nd test scene there is no baked light nor shadows. But in my main scene, the terrain seems to be lighted somehow (no directional light here):

But should look like this (with directional light and shadows enabled):

Not related to shadowask branch: I have trouble with baking lights for LODs - only LOD0 looks good, and others (less detailed) are too dark. I made sure that all meshes are visible, have uv2s, and have light baking enabled. I suspect that one (first?) mesh is covering others, so light can't be baked properly. I have no idea how to bake light for LODs. This is more visible for buildings than trees.

Baked shadows are quite different than dynamic shadows in same conditions (see screenshots)

Are these limitations, or just the result of my lack of knowledge?

Thanks, Marcin

cybereality

That doesn't look correct to me. Baked and real time will definitely look different, but not dramatically so. I would assume it has something to do with the terrain plug-in, but I've never used it.

Calinou

Missing property to disable shadow casting of baked meshes. The lack of one switch is getting more painful as LODs number increases (I'm using your plugin / script).

You can set the Cast Shadow property to Off on MeshInstances after baking lightmaps to do this. There is no way to have this be considered to On for lightmap baking only yet. However, disabling real-time shadow casting for a baked object will make dynamic objects appear to glow in its shadow, as they will not receive any shadow from the baked object. Therefore, I'm not sure if it makes sense to provide a built-in property for this yet.

marcinn

Thanks. Unfortunately, while checking new version of G4 and removing .godot caches, I incidentally removed directory with all projects. I'm trying to recover anything, but ext4 is not friendly in such cases. Weeks of work lost in seconds.

Use git. Make backups.

Best wishes, Marcin

cybereality

Yeah, won't get into my whole story how I lost 1 years worth of work, but after that I have crazy backups. I have a cloud and local auto-backup. I use Git. And I also manually copy the projects over to a second drive whenever I've made major progress (usually like every few weeks, just in case). I think this is safe. I used to try multiple cloud backups, but they end up conflicting and messing up the version history. But I think this is enough.

marcinn

Yes, Git + backup to 2nd drive sounds good enough. Git does not like binaries / big files. I was too lazy to cleanup projects and setup lfs. Funny fact: 20+ years ago I was making prototypes of games and I lost everything, too. :#

cybereality

You want to make sure one of the solutions is automatic though. Because you can forget to push to git. But if you have a backup service, you don't have to worry about it. And the chance of the cloud backup and git dying at the same time is low (but still not a bad idea to have a manual backup once every 2 weeks to be safe).

marcinn

@cybereality I recreated the project from partially recovered files and going back to lightmapping. I've found old topics on reddit about making meshes unique before baking. I didn't knew about this.

I'm building the scene by placing object instances on it, by drag&drop, by duplicating them, or by using the scatter tool. For now let's talk about simple dragging items on the scene.

So, I have a house object saved as a separate scene. The root node is Spatial, because it will handle LODs.

After placing it on the main scene, only the Spatial reference is visible in the tree:

I can't make it's mesh unique, because I have no access to it's MeshInstances. Should I make it local first, and then make unique meshes for LODs which will be used in baking? Is losing references to original object scenes a part of official workflow with static lightmapper?

Thanks. Marcin

marcinn

Hi.

Sorry for asking another noob question. I've baked directional light using mode "All" in Godot 3.4.2-stable, then I disabled the light. I see that tree shadows are baked too, but instead leaves (normally cut with alpha scissors in material) there are visible shadows of meshes (planes used for leaves). Is expected that shadows are baked in "All lights" mode?

My trees are built from two meshes - one for casting shadows only (Use in baked light set to true, Generate lightmaps disabled), and second for the tree itself (no shadows, Use in baked light and Generate lightmaps enabled). Please bear in mind that ground is built with HTerrain plugin, which isn't working (or isn't working well) with baked lighting, so let's focus on the house and trees.

I think I can use detailed mesh for creating precise shadows, bake them in "All" mode, and achieve better performance for low end GPUs. I'll try this later, but still wondering is this expected, knowing that Calinou's shadowmaps branch isn't merged yet. Of course the lighting and shadowing during gameplay are very limited due to their static nature, but I can sacrifice them for a performance.

I'm trying to achieve something similar to SpinTires / MudRunner - a good visuals and performance. They baked almost everything, there are no dynamic lights except one for car's front lights, there are faked shadow blobs for cars, quite limited visibility, and color tricks for day-night cycle. My hardware can drive ST/MR up to 35fps on full screen. My test project in Godot, with all lights baked, achieves similar performance. That's good.

FYI: there is interesting article about tricks used in SpinTires: https://www.gamedeveloper.com/programming/mud-and-water-of-spintires-mudrunner

Regards, Marcin

Calinou

Is expected that shadows are baked in "All lights" mode?

Yes, as both direct and indirect light is baked when using the All bake mode. Direct light casts a pretty obvious shadow, since it's quite bright.

The fact that alpha scissor isn't working with such shadows is probably a bug (or a missing feature in the lightmapper). I can't find any open issues about it on GitHub, so feel free to create an issue there with a minimal reproduction project attached.

marcinn

@Calinou said:

Yes, as both direct and indirect light is baked when using the All bake mode.

Ok, thanks.

The fact that alpha scissor isn't working with such shadows is probably a bug (or a missing feature in the lightmapper).

That's something else. I created a test project and alpha scissor gives a shadow.

There is something wrong with my mesh used for shadowing the tree, which works for dynamic shadows but not for baked. The mesh was used in baking lights without making it unique, so maybe it is broken somehow.

But when I created asset from the scratch (from glb file), it works as expected. The one thing is that baked shadows are more blurry (also for ultra quality).

The difference between baked and dynamic shadows

I can live with that, but I'll give shadowmasking another try.

Thanks.

cybereality

For low end and mobile you basically have to use bake mode all. Real time shadows are too slow unless for very small scenes. While you can reduce settings (like resolution) and get it playable, the graphics will not look that great. So it is better to just bake everything if possible. For the leaves, check the Depth Draw Mode on the Parameters for the Material. It should be on Opaque Pre-Pass. I just tested and confirmed this works with shadows with alpha scissor.

marcinn

Thanks. I'll check that.

marcinn

Hi.

Do you know any workaround for baking lightmaps for LODs?

Lightmap isn't baked for hidden objects, so all LOD meshes must be visible in editor. This causes a second issue - LOD meshes are overlapped by themselves, so lightmap generated for them is wrong (they're mostly in shadow).

I've recorded a short video showing these issues:

Note: cube-lod0 mesh is slightly bigger than cube-lod1 to visualize the issue.