Rust binding for the Shaderc library.
This crate contains the higher-level Rust-friendly interface for the
Shaderc library. For the lower-level C interface, please see the
[shaderc-sys](https://docs.rs/shaderc-sys) crate.
The [Shaderc](https://github.com/google/shaderc) library provides an API
for compiling GLSL/HLSL source code to SPIRV modules. It has been shipping
in the Android NDK since version r12b.
The order of preference in which the build script will attempt to obtain
Shaderc can be controlled by several options, which are passed through to
shaderc-sys when building shaderc-rs:
1. The option `--features build-from-source` will prevent automatic library
detection and force building from source.
2. If the `SHADERC_LIB_DIR` environment variable is set to
`/path/to/shaderc/libs/`, it will take precedence and
`libshaderc_combined.a` (and the glslang and SPIRV libraries on Linux)
will be searched in the `/path/to/shaderc/libs/` directory.
3. On Linux, `/usr/lib/` will be automatically searched for system libraries
if none of the above were given.
4. If no other option was set or succeeded, shaderc-sys will fall back to
checking out and compiling a copy of Shaderc. This procedure is quite
slow.
# Examples
Compile a shader into SPIR-V binary module and assembly text:
```
use shaderc;
let source = "#version 310 es\n void EP() {}";
let mut compiler = shaderc::Compiler::new().unwrap();
let mut options = shaderc::CompileOptions::new().unwrap();
options.add_macro_definition("EP", Some("main"));
let binary_result = compiler.compile_into_spirv(
source, shaderc::ShaderKind::Vertex,
"shader.glsl", "main", Some(&options)).unwrap();
assert_eq!(Some(&0x07230203), binary_result.as_binary().first());
let text_result = compiler.compile_into_spirv_assembly(
source, shaderc::ShaderKind::Vertex,
"shader.glsl", "main", Some(&options)).unwrap();
assert!(text_result.as_text().starts_with("; SPIR-V\n"));
```