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I'm creating a resource pack with lots of emissive textures. I'm having trouble retexturing the signal aspect for the single and dual signals. I've located the corresponding images and created emissive textures, however, the signals don't use it.

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I need information on whether it is possible to create an emissive texture for the signals or is it hard coded.

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As I recall, emissive lighting required a special model that specified which quads were affected, so would require some code changes to work.

You might be able to achieve it with an add-on do the heavy lifting, but it is beyond resource packs alone.

If I recall, Signals are TESRs with special opengl code for emissivity on the lamps. I don't know enough about emissive textures to recommend a solution. (Possible they could be redesigned to use 'emissive textures', if I knew how to do that. But it's not a priority.)