texture2ddecoder

A pure Rust no-std texture decoder for the following formats: - ATC - Adreno Texture Compression (detailed paper) - ASTC - Adaptive Scalable Texture Compression - BCn - Block Compression - ETC - Ericsson Texture Compression - PVRTC - PowerVR Texture Compression

and with alloc: - Crunch & Unity's Crunch (unity branch)

Features

alloc (optional, default)

• ~35% faster pvrtc decoding
• crunch decoding

Functions

Provides a decode function for each format, as well as a block decode function all formats besides PVRTC. Besides some exceptions, the signature of the decode functions is as follows:

    fn decode_format(data: &[u8], width: usize, height: usize, image: &mut [u32]) -> Result<(), &'static str>
    // data: the compressed data, expected to be width * height / block_size in size
    // width: the width of the image
    // height: the height of the image
    // image: the buffer to write the decoded image to, expected to be width * height in size
    fn decode_format_block(data: &[u8], outbuf: &mut [u32]) -> Result<(), &'static str>
    // data: the compressed data (block), expected to be block_size in size
    // outbuf: the buffer to write the decoded image to, expected to be block_size in size

The exceptions are: - ASTC: the (block) decode function takes the block size as an additional parameter - BC6: there are two additional decode functions for the signed and unsigned variants - PVRTC: the decode function takes the block size as an additional parameter, and there are two additional decode functions for the 2bpp and 4bpp variants - Crunch & Unity's Crunch: The texture's dimensions and metadata are stored in the file itself, the header must be parsed with crnd_get_texture_info() from CrnTextureInfo struct first, then pass the metadata to the decoder. There's no block decompression function.

Here is a list of the formats and their corresponding functions: - ATC - decode_atc_rgb4 - decode_atc_rgb4_block - decode_atc_rgba8 - decode_atc_rgba8_block - ASTC - decode_astc - decode_astc_block - various decode_astc_(block_)_x_y functions, where x and y are the block size - BCn - decode_bc1 - decode_bc1_block - decode_bc3 - decode_bc3_block - decode_bc4 - decode_bc4_block - decode_bc5 - decode_bc5_block - decode_bc6 - decode_bc6_block - decode_bc6_signed - decode_bc6_block_signed - decode_bc6_unsigned - decode_bc6_block_unsigned - decode_bc7 - decode_bc7_block - ETC - decode_etc1 - decode_etc1_block - decode_etc2_rgb - decode_etc2_rgb_block - decode_etc2_rgba1 - decode_etc2_rgba1_block - decode_etc2_rgba8 - decode_etc2_rgba8_block - decode_eacr - decode_eacr_block - decode_eacr_signed - decode_eacr_signed_block - decode_eacrg - decode_eacrg_block - PVRTC - decode_pvrtc - decode_pvrtc_2bpp - decode_pvrtc_4bpp - Crunch - decode_crunch - Unity Crunch - decode_unity_crunch

Roadmap

• documentation
• replacing u32 color output with RGBA structure
• finding the original sources for the decoders
• supporting more than BGRA32 output
• adding additional formats

Format Progress

• [x] ATC-RGB
• [x] ATC-RGBA
• [x] ASTC
• [x] BC1
• [x] BC3
• [x] BC4
• [x] BC5
• [x] BC6
• [x] BC7
• [x] EAC-R
• [x] EAC-RG
• [x] ETC1
• [x] ETC2
• [x] ETC2-A1
• [x] ETC2-A8
• [x] PVRTCI-2bpp
• [x] PVRTCI-4bpp
• [x] Crunched
• [x] DXT1
• [x] DXT5
• [x] ETC1
• [x] ETC2-A8

License & Credits

This crate itself is dual-licensed under MIT + Apache2.

The texture compression codecs themselves have following licenses: | Codec | License | Source | |----------------|---------------|---------------------------------------------------------------------------------------------------------------------------------------| | ATC | MIT | Perfare/AssetStudio - Texture2DDecoderNative/atc.cpp | | ASTC | MIT* | Ishotihadus/mikunyan - ext/decoders/native/astc.c | | BCn | MIT* | Perfare/AssetStudio - Texture2DDecoderNative/bcn.cpp | | ETC | MIT* | Ishotihadus/mikunyan - ext/decoders/native/etc.c | | f16 | MIT | Maratyszcza/FP16 | | PVRTC | MIT* | Ishotihadus/mikunyan - ext/decoders/native/pvrtc.c | | Crunch | PUBLIC DOMAIN | BinomialLLC/crunch | | Crunch (Unity) | ZLIB | Unity-Technologies/crunch | * in doubt if these are the original source and have not just taken/adopted the code from somewhere else