URP lighting for Skeleton Lit Unity Issues

spudonkey

Hello, I am currently having issues with the URP shader, in particular the skeleton lit one.

The part of the image attached on the left is a character I have imported from spine and the one on the left is some of my dressing sprites. As you can see the black linework in the left of the image seems to not be affected by the scene lighting and is super dark, the light colours exported by spine also get super bleached out using the skeleton lit shader.

It would be great to get consistant lighting across the board as at the moment they stick out a little too much. The tint option also doesn't appear to be working as when I turn it on I get this weird pink and green view. (See also attached.)

Any assistance would be most appreciated!

Spinebot

It seems like you are experiencing issues with the Universal Render Pipeline/2D/Spine/Skeleton Lit shader in Unity, where the lighting is not affecting your Spine assets as expected. This could be due to several factors, such as incorrect shader settings or issues with the normal maps. First, ensure that you are using the latest version of the Spine URP shaders and the spine-unity runtime. You might also want to check if the Light Affects Additive property is enabled, as it can influence how lighting affects your assets. Additionally, resetting the material in the Inspector and reassigning the texture and properties might help resolve any stray keywords or settings that could be causing the issue. If the problem persists, consider creating a minimal Unity project that replicates the issue and send it to Esoteric Software for further investigation.

Harald

@spudonkey Please also be sure to check the used Unity project color space (Linear vs Gamma color space) and whether you're perhaps using incorrect texture or material settings. See the documentation section here:
https://esotericsoftware.com/spine-unity-assets#Correct-Texture-Packer-export
If it's only the lit shader which appears off and the unlit shader appears normally it must be something else however. In that case please do send us a minimal Unity reproduction project to contact@esotericsoftware.com as Spinebot mentioned. You can send it as a zip file, briefly mentioning this forum thread URL so that we know the context.

spudonkey

Thanks for your speedy response Harald.
I have gone through the documentation with a fine tooth comb and everything appears to be set up correctly.

I have taken your advice and sent an email over citing this thread with a unity package with instructions on how to reproduce the difference I am seeing. Hopefully someone move versed with shaders than me will save the day...

Harald

@spudonkey I can see nothing obviously incorrectly lit in your example scene. There is a slight difference however in that your Shader Graph sprite shader ignores Environment lighting, which the Universal Render Pipeline/Spine/Skeleton Lit shader respects. So when turning off the Directional Light GameObject in your scene, your TX_Archer_Blue is completely black while the Spine skeleton GameObject shows some IBL lighting from the skybox.

If you don't want any environment light, you should in the Lighting window under the Environment tab set the Environment Lighting - Source to Color and as Ambient Color set pure black.

I noticed that you're not using the latest spine-unity 4.2 unitypackage (or a modified one), so you might also want to update that to the latest one in your project.

BTW: Please note that we prefer receiving a directly zipped project directory (without Library dir and the like), not a zip file of a unitypackage (here zipping it is not helpful). This makes it 1) faster to load for us and 2) safer to ensure all settings are equivalent to yours. I don't know your used Unity version for example.

spudonkey

Apologies, I have not had to package something up like that before for unity I will endevour to get the correct files to you next time.

I thought I was on the correct issue as downloaded from the links provided on the page you linked -
spine-unity 4.2 (updated 2025-09-26, changelog) & Unity 2019.3-6000.1: spine.urp-shaders 4.2 (updated 2025-09-01).

We are using Unity 6.000.028f1 so I thought these were the correct versions to use?

I see what you mean about my shader not taking on the ambient lighting. Which is confusing as it does in my project, however it does take on the direct lighting and it illustrates the difference in regards to the black linework. As you can see below linework of the Spine shader does not take on any lighting whether that be ambient or directional (see examples attached, one being strong ambient and the other strong directional.)

I have also done some experimenting and if I raise my linework value I can get a similar result with using the URP Spine Lit shader so I guess I have a workaround if needs be but it is a little puzzling why it is not working how I thought it would.

Harald

spudonkey Apologies, I have not had to package something up like that before for unity I will endevour to get the correct files to you next time.

No worries, it was not as explicitly stated in the first place and can obivoulsy be misunderstood easily.

spudonkey I thought I was on the correct issue as downloaded from the links provided on the page you linked -
spine-unity 4.2 (updated 2025-09-26, changelog) & Unity 2019.3-6000.1: spine.urp-shaders 4.2 (updated 2025-09-01).

Yes, these packages are the correct latest version. I just noticed that multiple files were imported/modified when I imported the spine-unity 2025-09-26 package. Whatever the reason for the difference, if you're using the latest version in your project, everything is fine.

We are using Unity 6.000.028f1 so I thought these were the correct versions to use?

Yes.

I see what you mean about my shader not taking on the ambient lighting. Which is confusing as it does in my project, however it does take on the direct lighting and it illustrates the difference in regards to the black linework. As you can see below linework of the Spine shader does not take on any lighting whether that be ambient or directional (see examples attached, one being strong ambient and the other strong directional.)

If your texture color is pure black, then it shouldn't take on any multiplicative light by definition. Multiplying RGB (0, 0, 0) with anything will still be (0, 0, 0). I wonder why you receive anything other than black in your other shaders?

Your albedo (previously simplified as "diffuse") texture color basically defines the material's reflectivity of light, 0 meaning not reflecting anything.

spudonkey I have also done some experimenting and if I raise my linework value I can get a similar result with using the URP Spine Lit shader so I guess I have a workaround if needs be but it is a little puzzling why it is not working how I thought it would.

The main question is why does your other shader turn black into anything but black when lit.

spudonkey

Ah you genius!

Yup it was my shader, I followed a tutorial on how to get a sprite shader and it had me multiply the textures via the vertex colour and unhooking that fixed my black values (and retained the shadows so I am not sure why they had this step in the guide).

Thanks for all the help!

Harald

@spudonkey Glad it helped, thanks for your kind words. 😃

I followed a tutorial on how to get a sprite shader and it had me multiply the textures via the vertex colour and unhooking that fixed my black values

That does not explain why your black becomes brighter though, multiplying texture RGB value (0, 0, 0) with any vertex color is still (0, 0, 0).

spudonkey

I get what you are saying but unhooking that multiply did fix it, potentially something weird in Unity shader graphs?

Harald

That's strange indeed. Are you sure you had a multiply operation and not an addition there? You could share a screenshot of the nodes if you like. Anyway, no need to dig deeper into this mystery if you've got a working solution already.