Im not sure if theres a better solution, but you could use a texture array or some other fancy object like that, and have 8 layers of float textures, so you then just sample each layer separately. (maybe theres a RGBA float format so you only need 2 textures?)

Im not sure if theres a better solution, but you could use a texture array or some other fancy object like that, and have 8 layers of float textures, so you then just sample each layer separately.