Lightmap support broken

[JulianGro]

A test world is available here: https://metaverse.kuro.ryuu.eu/public/Bazaar/Worlds/ThroneRoom/throne.json Apparently, lightmap support broke between version 2025.03.3 and 2025.05.1

[HifiExperiments]

I suspect it’s not properly selecting the other tex coord set? lightmaps used to always assume the second set, but now respect the value from the model, but that could be an issue in the model itself or something on our side

or…it could be from the material layering stuff that maybe broke the pipeline selection

[HifiExperiments]

ah ok I see, the material JSONs overrides the lightmap, e.g.: "lightMap": "textures/lightmap-furniture.png"

I think it will now need to be: "lightMap": { "url": "textures/lightmap-furniture.png", "texCoord": 1 }

[JulianGro]

I checked it with https://sandbox.babylonjs.com/ and it has the same behaviour. If you provide a lightmap without specifying which UV set to use, it also just uses the first UV set. I don't think anyone other than @keeshii has actually used lightmaps, so we should probably just keep the change to act the same as other pieces of software.

Specifying the UV set like in your latest comment works properly. Same banners with UV set specified:

[ksuprynowicz]

@JulianGro Are you sure it's the correct screenshot? On the screenshot you posted lightmaps are broken. Do they work correctly when UV set is specified?

[JulianGro]

@JulianGro Are you sure it's the correct screenshot? On the screenshot you posted lightmaps are broken. Do they work correctly when UV set is specified?

Yes. I only fixed the banners. Not the rest of the world.

[ksuprynowicz]

Ah, makes sense.

[HifiExperiments]

are we good to close this then?

[JulianGro]

I guess so. We changed this a long time ago and no one has complained, so I don't think this even needs much of a notice.