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"""
A Pillow loader for .ftc and .ftu files (FTEX)
Jerome Leclanche <jerome@leclan.ch>
The contents of this file are hereby released in the public domain (CC0)
Full text of the CC0 license:
https://creativecommons.org/publicdomain/zero/1.0/
Independence War 2: Edge Of Chaos - Texture File Format - 16 October 2001
The textures used for 3D objects in Independence War 2: Edge Of Chaos are in a
packed custom format called FTEX. This file format uses file extensions FTC
and FTU.
* FTC files are compressed textures (using standard texture compression).
* FTU files are not compressed.
Texture File Format
The FTC and FTU texture files both use the same format. This
has the following structure:
{header}
{format_directory}
{data}
Where:
{header} = {
u32:magic,
u32:version,
u32:width,
u32:height,
u32:mipmap_count,
u32:format_count
}
* The "magic" number is "FTEX".
* "width" and "height" are the dimensions of the texture.
* "mipmap_count" is the number of mipmaps in the texture.
* "format_count" is the number of texture formats (different versions of the
same texture) in this file.
{format_directory} = format_count * { u32:format, u32:where }
The format value is 0 for DXT1 compressed textures and 1 for 24-bit RGB
uncompressed textures.
The texture data for a format starts at the position "where" in the file.
Each set of texture data in the file has the following structure:
{data} = format_count * { u32:mipmap_size, mipmap_size * { u8 } }
* "mipmap_size" is the number of bytes in that mip level. For compressed
textures this is the size of the texture data compressed with DXT1. For 24 bit
uncompressed textures, this is 3 * width * height. Following this are the image
bytes for that mipmap level.
Note: All data is stored in little-Endian (Intel) byte order.
"""
from __future__ import annotations
import struct
from enum import IntEnum
from io import BytesIO
from . import Image, ImageFile
MAGIC = b"FTEX"
class Format(IntEnum):
DXT1 = 0
UNCOMPRESSED = 1
class FtexImageFile(ImageFile.ImageFile):
format = "FTEX"
format_description = "Texture File Format (IW2:EOC)"
def _open(self):
if not _accept(self.fp.read(4)):
msg = "not an FTEX file"
raise SyntaxError(msg)
struct.unpack("<i", self.fp.read(4)) # version
self._size = struct.unpack("<2i", self.fp.read(8))
mipmap_count, format_count = struct.unpack("<2i", self.fp.read(8))
self._mode = "RGB"
# Only support single-format files.
# I don't know of any multi-format file.
assert format_count == 1
format, where = struct.unpack("<2i", self.fp.read(8))
self.fp.seek(where)
(mipmap_size,) = struct.unpack("<i", self.fp.read(4))
data = self.fp.read(mipmap_size)
if format == Format.DXT1:
self._mode = "RGBA"
self.tile = [("bcn", (0, 0) + self.size, 0, 1)]
elif format == Format.UNCOMPRESSED:
self.tile = [("raw", (0, 0) + self.size, 0, ("RGB", 0, 1))]
else:
msg = f"Invalid texture compression format: {repr(format)}"
raise ValueError(msg)
self.fp.close()
self.fp = BytesIO(data)
def load_seek(self, pos):
pass
def _accept(prefix):
return prefix[:4] == MAGIC
Image.register_open(FtexImageFile.format, FtexImageFile, _accept)
Image.register_extensions(FtexImageFile.format, [".ftc", ".ftu"])
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