basisu_c_sys 0.9.0

# Rust binding and wrappers for the Basis Universal pure C API.

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Rust binding and wrappers for the basisu pure C API, through FFI on native and wasm32. See also <https://github.com/BinomialLLC/basis_universal/wiki#encoder-and-transcoding-c-api-documentation>.

This crate also contains an optional high level API that is easier to use with `wgpu-types`. Enabling the `extra` cargo feature to use the high level `BasisuEncoder` and `BasisuTranscoder`.

## Implementation details on wasm build

Greatly inspired by <https://github.com/rafaelbeckel/test-c-rust-wasm>

The wasm build compiles the Basis Universal C++ sources together with a vendored
[musl](https://musl.libc.org/) libc and emscripten
[libc++/libc++abi](https://github.com/emscripten-core/emscripten) directly from source.

⚠️ Note: this requires a relatively new clang version (Ubuntu 26.04 with clang 21 is tested in CI).

## Feature flags

- `encoder`: Enable basisu encoder, which will significantly increase the binary size. By default only transcoder is enabled.
- `serde`: Enable `serde` on some structs.
- `extra`: Enable extra high level encoder and transcoder API that is easier to use with `wgpu-types`.
- `std`

Feature flags to enable specific transcode target:

- `transcode_etc1s_bc1`
- `transcode_etc1s_bc3`

- `transcode_default`:
  - `transcode_etc1s_bc4_5`
  - `transcode_etc1s_bc7`
  - `transcode_etc1s_etc2`
  - `transcode_uastc`
  - `transcode_uastc_hdr`
  - `transcode_xuastc`
  - `transcode_astc`

It's recommended to disable unused targets (especially for ETC1S) to reduce binary size.

PVRTC1, ATC, FXT1, PVRTC2 are always disabled since they are rarely used. Note: Some combinations may fail to compile due to upstream bugs.