The bot is just there is get any obvious answers out of the way I think 😉
I think your best bet might be to import to a DCC via a .JSON importer, then export from there.
There may be other projects like this one where you can import into Blender:
https://github.com/NarrowsProjects/blender_json_to_mesh_spine_4.0_builder
(I would paste it as the script but this forum cuts off the url at '.0_builder' and breaks the link, just manually copy and paste it from above.)
But it's Spine version 4.0, and using Blender 3.4 and doesn't transfer bone deformation.
I would just keep looking or support one of the existing projects, you may find other projects like it that do what you need and they may just need some backing and support to add that one last necessary feature.
If not, you'd potentially be waiting on my IO between Spine and Blender.
SimonHeggie/Blender-Spine-IO
My current focus is on the exporter. You COULD commission me to drop my exporter for now and focus on the importer and GLTF export solution that you can use through blender. Because it does require some specific runtime helpers, and plenty of work, but had planned on making it eventually. Otherwise there's some manual work here to bridge some gaps.
You would in theory import your spine character to blender then export as GLTF using a basic rgb/emission (1)/Alpha PBR setup.
You may be aware that there are some of the differences in what GLTF can do compared to Spine; From my experience you will be better off relying on bone/empty driven animation for instance to drive shader stuff like fades and dims on the engine side while keeping a useful rig to work on.
Because there are dedicated solutions for this, by they don't work for every engine. Then, you could get an extension to the standard PBR shader to add blend at least multiply and additive blend modes.
aaronfranke/gltf-extensionstree/OMI_materials_blend/extensions/2.0/OMI_materials_blend
That stuff is possible with some cross engine custom GLTF extensions.
Combining geo can cause sorting issues unless it's baked into the sorting index of your geometry, AND that's being read by the engine. Gotta combine both geo, textures and shaders like Spine does in order to justify using GLTF instead of .JSON for serious real time projects.
People like us working on these solutions for you could do with donations to allow us to live long enough to keep working on these project 😉
Our focus is what ever puts food on the table just like anyone else, so if you want to see this kind of flexibility, you could support people like me.
-S
