slang-spirv-compiler-helper

CLI tool that compiles Slang shaders to SPIR-V and generates C++20 module files (.cppm) with #embed for the bytecode and compile-time reflection data.

Layout

slang-spirv-compiler-helper/
├── CMakeLists.txt
├── CMakePresets.json
├── vcpkg.json
├── cmake/
│   ├── ConfigureClangTidy.cmake
│   └── SlangSpirVCompiler.cmake       # CMake module for build-system integration
├── src/
│   ├── CMakeLists.txt
│   └── cli_tool/
│       ├── CMakeLists.txt
│       ├── main.cpp                    # CLI entry point
│       └── ShaderReflection.cppm       # Shared type module (copy into your project)
├── examples/
│   ├── compile_examples.sh            # Run to test all example shaders
│   ├── output/                        # Generated .spv + .cppm files
│   └── shaders/                       # Example .slang files
└── external/
    └── cppLoggingInterface/

Prerequisites

• CMake ≥ 3.15
• A C++20-capable compiler
• vcpkg available with VCPKG_ROOT set

Build

cmake --preset default
cmake --build build --parallel

The CLI executable is placed at build/bin/<config>/slang-spirv-compiler.

Usage

slang-spirv-compiler <input.slang> [-e entry] [-s stage] [-o prefix] \
    <namespace...> <class-name>

Each invocation produces two files:

• <prefix>.spv — SPIR-V binary
• <prefix>.cppm — C++20 module with #embedd bytecode + constexpr reflection

The positional arguments define the module, namespace, and struct names:

Argument	Example	Produces
App Fragment	namespace segments	module Shaders.App.Fragment.… namespace Shaders::App::Fragment
ComplexFragmentShader	last segment = struct name	struct ComplexFragmentShader

Example

slang-spirv-compiler shaders/triangle.slang -e main -s fragment \
    -o build/generated/triangle MyApp Triangle

Generated triangle.cppm:

export module Shaders.MyApp.Triangle;
import ShaderReflection;
export namespace Shaders::MyApp {
struct Triangle {
    static std::span<const std::uint32_t> GetSpirvWords() noexcept { ... }  // #embed
    static vk::raii::ShaderModule CreateModule(vk::raii::Device const&) { ... }
    static constexpr ShaderStage GetStage() noexcept { return ShaderStage::eFragment; }
    static constexpr std::span<const Binding> GetBindings() noexcept { ... }
private:
    static constexpr std::array<Binding, 3> kBindings{{ ... }};
};
}

CMake integration

Include the module, compile shaders, and add them to your target:

# Option A: add to module path
list(APPEND CMAKE_MODULE_PATH "/path/to/slang-spirv-compiler-helper/cmake")
include(SlangSpirVCompiler)

# Option B: include directly
# include(/path/to/slang-spirv-compiler-helper/cmake/SlangSpirVCompiler.cmake)

# Compile shaders — each row creates an add_custom_command so CMake
# rebuilds only the shaders whose source changed.
# Generated module: Shaders.MyApp.mesh_vert (etc.)
# Generated namespace: Shaders::MyApp
# Generated struct: mesh_vert (etc.)
add_slang_shaders(
    TARGET      MyShaders
    OUTPUT_DIR  "${CMAKE_BINARY_DIR}/generated/shaders"
    NAMESPACE   MyApp
    SHADER_DIR  "${CMAKE_SOURCE_DIR}/shaders"
    COMPILER    slang-spirv-compiler
    OPT_LEVEL   2
    SHADERS
        mesh_vert  mesh.slang    vertex   main
        mesh_frag  mesh.slang    fragment main
        compute    compute.slang compute  computeMain
)

# The function automatically copies ShaderReflection.cppm (the shared
# module) into OUTPUT_DIR and lists all .cppm files in the target
# property SLANG_CPPM_FILES:
get_target_property(SHADER_CPPM MyShaders SLANG_CPPM_FILES)
target_sources(my_app PRIVATE ${SHADER_CPPM})

| OPT_LEVEL | 0, 1, 2, or 3 | Optimization level passed as -O flag to the compiler (default: none) |

If you keep the cmake module outside the project tree (e.g. installed), set SHARED_MODULE_DIR before calling add_slang_shaders:

set(SHARED_MODULE_DIR "/path/to/ShaderReflection.cppm/dir")
include(/path/to/SlangSpirVCompiler.cmake)

Manual use (without cmake module)

If you don't use add_slang_shaders(), copy ShaderReflection.cppm from src/cli_tool/ into your project and add generated .cppm files with:

set_source_files_properties(generated/triangle.cppm PROPERTIES
    COMPILE_OPTIONS "-Wno-c23-extensions"
)

Examples

Run examples/compile_examples.sh after building to compile all 8 example shaders:

File	Style	Stage	Bindings
triangle.slang	HLSL compat register + [[vk::binding]]	fragment	ConstantBuffer, Texture2D, Sampler
vertex.slang	HLSL compat register + [[vk::binding]]	vertex	ConstantBuffer
compute.slang	HLSL compat register + [[vk::binding]]	compute	RW/RO StructuredBuffer
parameter_block.slang	register + [[vk::binding]]	fragment	ParameterBlock + ConstantBuffer
hlsl_compat_auto.slang	register, no [[vk::binding]]	fragment	Auto-assigned bindings
mixed_binding.slang	Mixed explicit + auto	fragment	Explicit ConstantBuffer + auto textures
pure_slang.slang	Pure Slang, no annotations	fragment	Auto-assigned
pure_slang_explicit.slang	Pure Slang + [[vk::binding]]	fragment	Fully explicit