Lighting.j3md require Proper normal (vertex/face direction) in Mesh. it is you need to fill this:
mesh.setBuffer(VertexBuffer.Type.Normal, 3, nb);
for full quad for example you can fill it like:
nb.put(normalDirection.x).put(normalDirection.y).put(normalDirection.z);
nb.put(normalDirection.x).put(normalDirection.y).put(normalDirection.z);
nb.put(normalDirection.x).put(normalDirection.y).put(normalDirection.z);
nb.put(normalDirection.x).put(normalDirection.y).put(normalDirection.z);
Also it require Light so it will not be just black and Front of face will be lit. it can be done with:
rootNode.addLight(al) //ambient light - overall light not depends on normals, but normals you need to see front faces
rootNode.addLight(dl) //directional light - it depends on normals from your mesh
As i know this 2 things(light/normals) is required for your Lighting.j3md to not be “black”(not lit).
Unshaded do not need light/normals. PBR also need lightProbe to make metallic work. As you can see each material can have some “requirements”.
Anyway imo TestCase is always easiest way to solve.