116 lines
3.4 KiB
Python
116 lines
3.4 KiB
Python
"""
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A Pillow loader for .ftc and .ftu files (FTEX)
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Jerome Leclanche <jerome@leclan.ch>
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The contents of this file are hereby released in the public domain (CC0)
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Full text of the CC0 license:
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https://creativecommons.org/publicdomain/zero/1.0/
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Independence War 2: Edge Of Chaos - Texture File Format - 16 October 2001
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The textures used for 3D objects in Independence War 2: Edge Of Chaos are in a
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packed custom format called FTEX. This file format uses file extensions FTC
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and FTU.
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* FTC files are compressed textures (using standard texture compression).
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* FTU files are not compressed.
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Texture File Format
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The FTC and FTU texture files both use the same format. This
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has the following structure:
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{header}
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{format_directory}
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{data}
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Where:
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{header} = {
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u32:magic,
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u32:version,
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u32:width,
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u32:height,
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u32:mipmap_count,
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u32:format_count
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}
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* The "magic" number is "FTEX".
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* "width" and "height" are the dimensions of the texture.
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* "mipmap_count" is the number of mipmaps in the texture.
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* "format_count" is the number of texture formats (different versions of the
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same texture) in this file.
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{format_directory} = format_count * { u32:format, u32:where }
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The format value is 0 for DXT1 compressed textures and 1 for 24-bit RGB
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uncompressed textures.
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The texture data for a format starts at the position "where" in the file.
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Each set of texture data in the file has the following structure:
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{data} = format_count * { u32:mipmap_size, mipmap_size * { u8 } }
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* "mipmap_size" is the number of bytes in that mip level. For compressed
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textures this is the size of the texture data compressed with DXT1. For 24 bit
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uncompressed textures, this is 3 * width * height. Following this are the image
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bytes for that mipmap level.
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Note: All data is stored in little-Endian (Intel) byte order.
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"""
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from __future__ import annotations
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import struct
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from enum import IntEnum
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from io import BytesIO
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from . import Image, ImageFile
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MAGIC = b"FTEX"
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class Format(IntEnum):
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DXT1 = 0
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UNCOMPRESSED = 1
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class FtexImageFile(ImageFile.ImageFile):
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format = "FTEX"
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format_description = "Texture File Format (IW2:EOC)"
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def _open(self) -> None:
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if not _accept(self.fp.read(4)):
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msg = "not an FTEX file"
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raise SyntaxError(msg)
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struct.unpack("<i", self.fp.read(4)) # version
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self._size = struct.unpack("<2i", self.fp.read(8))
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mipmap_count, format_count = struct.unpack("<2i", self.fp.read(8))
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self._mode = "RGB"
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# Only support single-format files.
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# I don't know of any multi-format file.
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assert format_count == 1
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format, where = struct.unpack("<2i", self.fp.read(8))
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self.fp.seek(where)
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(mipmap_size,) = struct.unpack("<i", self.fp.read(4))
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data = self.fp.read(mipmap_size)
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if format == Format.DXT1:
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self._mode = "RGBA"
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self.tile = [("bcn", (0, 0) + self.size, 0, 1)]
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elif format == Format.UNCOMPRESSED:
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self.tile = [("raw", (0, 0) + self.size, 0, ("RGB", 0, 1))]
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else:
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msg = f"Invalid texture compression format: {repr(format)}"
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raise ValueError(msg)
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self.fp.close()
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self.fp = BytesIO(data)
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def load_seek(self, pos: int) -> None:
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pass
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def _accept(prefix: bytes) -> bool:
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return prefix[:4] == MAGIC
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Image.register_open(FtexImageFile.format, FtexImageFile, _accept)
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Image.register_extensions(FtexImageFile.format, [".ftc", ".ftu"])
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