""" A Pillow loader for .dds files (S3TC-compressed aka DXTC) Jerome Leclanche <jerome@leclan.ch> Documentation: https://web.archive.org/web/20170802060935/http://oss.sgi.com/projects/ogl-sample/registry/EXT/texture_compression_s3tc.txt 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/ """ import struct from io import BytesIO from PIL import Image, ImageFile # Magic ("DDS ") DDS_MAGIC = 0x20534444 # DDS flags DDSD_CAPS = 0x1 DDSD_HEIGHT = 0x2 DDSD_WIDTH = 0x4 DDSD_PITCH = 0x8 DDSD_PIXELFORMAT = 0x1000 DDSD_MIPMAPCOUNT = 0x20000 DDSD_LINEARSIZE = 0x80000 DDSD_DEPTH = 0x800000 # DDS caps DDSCAPS_COMPLEX = 0x8 DDSCAPS_TEXTURE = 0x1000 DDSCAPS_MIPMAP = 0x400000 DDSCAPS2_CUBEMAP = 0x200 DDSCAPS2_CUBEMAP_POSITIVEX = 0x400 DDSCAPS2_CUBEMAP_NEGATIVEX = 0x800 DDSCAPS2_CUBEMAP_POSITIVEY = 0x1000 DDSCAPS2_CUBEMAP_NEGATIVEY = 0x2000 DDSCAPS2_CUBEMAP_POSITIVEZ = 0x4000 DDSCAPS2_CUBEMAP_NEGATIVEZ = 0x8000 DDSCAPS2_VOLUME = 0x200000 # Pixel Format DDPF_ALPHAPIXELS = 0x1 DDPF_ALPHA = 0x2 DDPF_FOURCC = 0x4 DDPF_PALETTEINDEXED8 = 0x20 DDPF_RGB = 0x40 DDPF_LUMINANCE = 0x20000 # dds.h DDS_FOURCC = DDPF_FOURCC DDS_RGB = DDPF_RGB DDS_RGBA = DDPF_RGB | DDPF_ALPHAPIXELS DDS_LUMINANCE = DDPF_LUMINANCE DDS_LUMINANCEA = DDPF_LUMINANCE | DDPF_ALPHAPIXELS DDS_ALPHA = DDPF_ALPHA DDS_PAL8 = DDPF_PALETTEINDEXED8 DDS_HEADER_FLAGS_TEXTURE = (DDSD_CAPS | DDSD_HEIGHT | DDSD_WIDTH | DDSD_PIXELFORMAT) DDS_HEADER_FLAGS_MIPMAP = DDSD_MIPMAPCOUNT DDS_HEADER_FLAGS_VOLUME = DDSD_DEPTH DDS_HEADER_FLAGS_PITCH = DDSD_PITCH DDS_HEADER_FLAGS_LINEARSIZE = DDSD_LINEARSIZE DDS_HEIGHT = DDSD_HEIGHT DDS_WIDTH = DDSD_WIDTH DDS_SURFACE_FLAGS_TEXTURE = DDSCAPS_TEXTURE DDS_SURFACE_FLAGS_MIPMAP = DDSCAPS_COMPLEX | DDSCAPS_MIPMAP DDS_SURFACE_FLAGS_CUBEMAP = DDSCAPS_COMPLEX DDS_CUBEMAP_POSITIVEX = DDSCAPS2_CUBEMAP | DDSCAPS2_CUBEMAP_POSITIVEX DDS_CUBEMAP_NEGATIVEX = DDSCAPS2_CUBEMAP | DDSCAPS2_CUBEMAP_NEGATIVEX DDS_CUBEMAP_POSITIVEY = DDSCAPS2_CUBEMAP | DDSCAPS2_CUBEMAP_POSITIVEY DDS_CUBEMAP_NEGATIVEY = DDSCAPS2_CUBEMAP | DDSCAPS2_CUBEMAP_NEGATIVEY DDS_CUBEMAP_POSITIVEZ = DDSCAPS2_CUBEMAP | DDSCAPS2_CUBEMAP_POSITIVEZ DDS_CUBEMAP_NEGATIVEZ = DDSCAPS2_CUBEMAP | DDSCAPS2_CUBEMAP_NEGATIVEZ # DXT1 DXT1_FOURCC = 0x31545844 # DXT3 DXT3_FOURCC = 0x33545844 # DXT5 DXT5_FOURCC = 0x35545844 def _decode565(bits): a = ((bits >> 11) & 0x1f) << 3 b = ((bits >> 5) & 0x3f) << 2 c = (bits & 0x1f) << 3 return a, b, c def _c2a(a, b): return (2 * a + b) // 3 def _c2b(a, b): return (a + b) // 2 def _c3(a, b): return (2 * b + a) // 3 def _dxt1(data, width, height): # TODO implement this function as pixel format in decode.c ret = bytearray(4 * width * height) for y in range(0, height, 4): for x in range(0, width, 4): color0, color1, bits = struct.unpack("<HHI", data.read(8)) r0, g0, b0 = _decode565(color0) r1, g1, b1 = _decode565(color1) # Decode this block into 4x4 pixels for j in range(4): for i in range(4): # get next control op and generate a pixel control = bits & 3 bits = bits >> 2 if control == 0: r, g, b = r0, g0, b0 elif control == 1: r, g, b = r1, g1, b1 elif control == 2: if color0 > color1: r, g, b = _c2a(r0, r1), _c2a(g0, g1), _c2a(b0, b1) else: r, g, b = _c2b(r0, r1), _c2b(g0, g1), _c2b(b0, b1) elif control == 3: if color0 > color1: r, g, b = _c3(r0, r1), _c3(g0, g1), _c3(b0, b1) else: r, g, b = 0, 0, 0 idx = 4 * ((y + j) * width + x + i) ret[idx:idx+4] = struct.pack('4B', r, g, b, 255) return bytes(ret) def _dxtc_alpha(a0, a1, ac0, ac1, ai): if ai <= 12: ac = (ac0 >> ai) & 7 elif ai == 15: ac = (ac0 >> 15) | ((ac1 << 1) & 6) else: ac = (ac1 >> (ai - 16)) & 7 if ac == 0: alpha = a0 elif ac == 1: alpha = a1 elif a0 > a1: alpha = ((8 - ac) * a0 + (ac - 1) * a1) // 7 elif ac == 6: alpha = 0 elif ac == 7: alpha = 0xff else: alpha = ((6 - ac) * a0 + (ac - 1) * a1) // 5 return alpha def _dxt5(data, width, height): # TODO implement this function as pixel format in decode.c ret = bytearray(4 * width * height) for y in range(0, height, 4): for x in range(0, width, 4): a0, a1, ac0, ac1, c0, c1, code = struct.unpack("<2BHI2HI", data.read(16)) r0, g0, b0 = _decode565(c0) r1, g1, b1 = _decode565(c1) for j in range(4): for i in range(4): ai = 3 * (4 * j + i) alpha = _dxtc_alpha(a0, a1, ac0, ac1, ai) cc = (code >> 2 * (4 * j + i)) & 3 if cc == 0: r, g, b = r0, g0, b0 elif cc == 1: r, g, b = r1, g1, b1 elif cc == 2: r, g, b = _c2a(r0, r1), _c2a(g0, g1), _c2a(b0, b1) elif cc == 3: r, g, b = _c3(r0, r1), _c3(g0, g1), _c3(b0, b1) idx = 4 * ((y + j) * width + x + i) ret[idx:idx+4] = struct.pack('4B', r, g, b, alpha) return bytes(ret) class DdsImageFile(ImageFile.ImageFile): format = "DDS" format_description = "DirectDraw Surface" def _open(self): magic, header_size = struct.unpack("<II", self.fp.read(8)) if header_size != 124: raise IOError("Unsupported header size %r" % (header_size)) header_bytes = self.fp.read(header_size - 4) if len(header_bytes) != 120: raise IOError("Incomplete header: %s bytes" % len(header_bytes)) header = BytesIO(header_bytes) flags, height, width = struct.unpack("<3I", header.read(12)) self.size = (width, height) self.mode = "RGBA" pitch, depth, mipmaps = struct.unpack("<3I", header.read(12)) reserved = struct.unpack("<11I", header.read(44)) # pixel format pfsize, pfflags = struct.unpack("<2I", header.read(8)) fourcc = header.read(4) bitcount, rmask, gmask, bmask, amask = struct.unpack("<5I", header.read(20)) if fourcc == b"DXT1": self.decoder = "DXT1" codec = _dxt1 elif fourcc == b"DXT5": self.decoder = "DXT5" codec = _dxt5 else: raise NotImplementedError("Unimplemented pixel format %r" % fourcc) self.tile = [ (self.decoder, (0, 0) + self.size, 0, (self.mode, 0, 1)) ] def load_seek(self, pos): pass class DXT1Decoder(ImageFile.PyDecoder): _pulls_fd = True def decode(self, buffer): try: self.set_as_raw(_dxt1(self.fd, self.state.xsize, self.state.ysize)) except struct.error: raise IOError("Truncated DDS file") return 0, 0 class DXT5Decoder(ImageFile.PyDecoder): _pulls_fd = True def decode(self, buffer): try: self.set_as_raw(_dxt5(self.fd, self.state.xsize, self.state.ysize)) except struct.error: raise IOError("Truncated DDS file") return 0, 0 Image.register_decoder('DXT1', DXT1Decoder) Image.register_decoder('DXT5', DXT5Decoder) def _validate(prefix): return prefix[:4] == b"DDS " Image.register_open(DdsImageFile.format, DdsImageFile, _validate) Image.register_extension(DdsImageFile.format, ".dds")