fbxex_bin2json.py

# SPDX-License-Identifier: MIT

# fbxex_bin2json
# usage: /path/to/python3 /path/to/fbxex_bin2json.py /path/to/bg.fbx.bin
# Use with fbxex2gltf to convert to gltf

import sys
import json
import struct

def read_unpack(fmt, f):
	return struct.unpack(fmt, f.read(struct.calcsize(fmt)))

def trim_null(s):
	return s[:s.find(b"\x00")]

def convert_fbxex(f):
	if f.read(16) != b"fbxex\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00":
		raise Exception("Not fbxex format")
	json_root = {}
	fbxex_obj = {}
	json_root["fbxex"] = fbxex_obj
	f.read(4) # ???
	texture_obj = {}
	fbxex_obj["texture"] = texture_obj
	texture_obj["count"] = int.from_bytes(f.read(4), byteorder="little")
	for i in range(texture_obj["count"]):
		texture_s_obj = {}
		texture_obj[str(i)] = texture_s_obj
		texture_s_obj["filename"] = trim_null(f.read(128)).decode("ASCII")
		texture_s_obj["index"] = i
	f.read(4) # ???
	material_obj = {}
	fbxex_obj["material"] = material_obj
	material_obj["count"] = int.from_bytes(f.read(4), byteorder="little")
	for i in range(material_obj["count"]):
		material_s_obj = {}
		material_obj[str(i)] = material_s_obj
		material_s_obj["filename"] = trim_null(f.read(128)).decode("ASCII")
		material_s_obj["index"] = int.from_bytes(f.read(4), byteorder="little")
		material_s_obj["texture_index"] = int.from_bytes(f.read(4), byteorder="little")
		material_s_obj["value"] = list(read_unpack('fffffffffffffffff', f))
	f.read(4) # ???
	node_obj = {}
	fbxex_obj["node"] = node_obj
	node_obj["count"] = int.from_bytes(f.read(4), byteorder="little")
	for i in range(node_obj["count"]):
		f.read(4) # ???
		node_s_obj = {}
		node_obj[str(i)] = node_s_obj
		node_s_obj["type"] = int.from_bytes(f.read(4), byteorder="little")
		if node_s_obj["type"] not in [0, 1]:
			raise Exception("Unknown node type")
		node_s_obj["child"] = int.from_bytes(f.read(4), byteorder="little", signed=True)
		node_s_obj["sibling"] = int.from_bytes(f.read(4), byteorder="little", signed=True)
		if node_s_obj["type"] == 1:
			node_s_obj["blendmode"] = int.from_bytes(f.read(4), byteorder="little")
			node_s_obj["alpha"] = int.from_bytes(f.read(4), byteorder="little")
			node_s_obj["matrix"] = list(read_unpack('ffffffffffffffff', f))
			node_vertex_s_obj = {}
			node_s_obj["vertex"] = node_vertex_s_obj
			node_vertex_s_obj["count"] = int.from_bytes(f.read(4), byteorder="little")
			for ii in range(node_vertex_s_obj["count"]):
				node_vertex_s_obj[str(ii)] = list(read_unpack('ffffffffffff', f))
			node_material_s_obj = {}
			node_s_obj["material"] = node_material_s_obj
			node_material_s_obj["count"] = int.from_bytes(f.read(4), byteorder="little")
			for ii in range(node_material_s_obj["count"]):
				node_material_s_s_obj = {}
				node_material_s_obj[str(ii)] = node_material_s_s_obj
				node_material_s_s_obj["index"] = int.from_bytes(f.read(4), byteorder="little")
				node_material_s_s_obj["vertexindexcount"] = int.from_bytes(f.read(4), byteorder="little")
				node_material_s_s_obj["vertexindex"] = [int.from_bytes(f.read(4), byteorder="little") for iii in range(node_material_s_s_obj["vertexindexcount"])]
	f.read(4) # ???
	anime_obj = {}
	fbxex_obj["anime"] = anime_obj
	anime_obj["count"] = int.from_bytes(f.read(4), byteorder="little")
	for i in range(anime_obj["count"]):
		anime_obj[str(i)] = list(read_unpack('Iffffffffffffffff', f))
	return json_root

if __name__ == "__main__":
	d = None
	with open(sys.argv[1], "rb") as f:
		d = convert_fbxex(f)
	with open(sys.argv[1] + ".json", "wb") as f:
		f.write(json.dumps(d).encode("ASCII"))