sub_sphere

The substance material-array surface shader: one material shades every sphere in the 9×9 grid. Roughness and metallic derive in-shader from the sphere's grid position (part-local world position against center + spacing — roughness sweeps +z, metallic sweeps +x), the albedo ramps porcelain dielectrics into a silver→gold→copper metal run, and shading is the engine forward PBR plus a fresnel-weighted, roughness-blurred specular and hemispheric irradiance from the shared studio_env() — so the metal half of the array reflects the same cove, softbox ring and rim slits the dome renders. array_albedo() is mirrored in sub_floor so floor reflections of the spheres carry the same ramp.