A python script to pack multiple files into 6 textures.

combine.py

import os
import png
import random

A = 255
B = 127

files_to_combine = [
    (["baseColor", "subsurface"], "tex1"),
    (["metallic", "specular", "specularTint", "roughness"], "tex2"),
    (["anisotropic", "sheen", "sheenTint", "clearcoat"], "tex3"),
    (["shadingNormal", "clearcoatGloss"], "tex4"),
    (["iridescence"], "tex6")
    (["emissive", "emissiveStrength"], "tex7")
]

orig_dir = "./images/"
dir = "./packed_images/"

name = "whatever"

while name != "thin" and name != "solid":
    name = input("thin or solid?: ")

if name == "thin":
    files_to_combine.append(
        (["specTrans", "diffuseTrans", "flatness"], "tex5"))
elif name == "solid":
    files_to_combine.append((["specTrans", "scatterDistance"], "tex5"))

for combination in files_to_combine:
    print(*combination)
    p = []
    numcols = 2048
    numrows = 2048
    for _ in range(0, numrows):
        x = []
        for _ in range(0,  numcols):
            x.append(0)
            x.append(0)
            x.append(0)
            x.append(0)
        p.append(x)
    for file in combination[0]:
        print(file)
        r = png.Reader(filename=orig_dir + file + ".png")
        t = r.read()
        for idx1, l in enumerate(t[2]):
            for idx, line in enumerate(l):
                p[idx1][idx] = min((p[idx1][idx]) + line, 255)
    w = png.Writer(2048, 2048, greyscale=False, alpha=True)
    f = open(dir + combination[1] + ".png", 'wb')
    w.write(f, p)
    print("Done writing " + dir + combination[1] + ".png")
    f.close()

    # for u in range(0, numrows):
    #     for i in range(0, numcols):
    #         p[u][i] += t[2][u][i]