ShaderTranslator

Cross-platform shader translation library for GZDoom, providing unified shader compilation from GLSL/HLSL to SPIR-V to Metal Shading Language (MSL) and HLSL.

Overview

ShaderTranslator provides a complete shader compilation pipeline for modern graphics APIs:

Supported Workflows:

GLSL → SPIR-V → MSL (Metal)
              → HLSL (D3D12)

HLSL → SPIR-V → MSL (Metal)    [Optional: requires DXC]
              → HLSL (D3D12)

Target Platforms:

• Metal (MSL): macOS/iOS Metal renderer
• Direct3D 12 (HLSL): Windows D3D12 renderer (optional)

Features

• Unified API: Compile from GLSL or HLSL to any target language
• SPIR-V Caching: Cache intermediate bytecode for faster re-compilation
• Platform Optimizations: Metal version targeting (2.0-2.4), HLSL shader models
• Resource Reflection: Automatic binding point translation
• Shader Stages: Vertex, Fragment, Compute shader support
• Preprocessor: Define macros for conditional compilation

Building

ShaderTranslator is built as part of the GZDoom build system when Vulkan or Metal support is enabled.

CMake Options

• SHADER_TRANSLATOR_ENABLE_HLSL: Enable HLSL output (SPIR-V → HLSL) (default: ON)
• SHADER_TRANSLATOR_ENABLE_HLSL_INPUT: Enable HLSL input (HLSL → SPIR-V via DXC) (default: OFF)
• SHADER_TRANSLATOR_USE_SYSTEM_DXC: Use system DXC from VulkanSDK instead of bundled (default: ON)

Dependencies

Required:

• glslang: GLSL to SPIR-V compilation (from ZVulkan)
• SPIRV-Cross: SPIR-V to MSL/HLSL translation (from ZVulkan)
  • spirv-cross-core
  • spirv-cross-glsl
  • spirv-cross-msl

Optional:

• spirv-cross-hlsl: HLSL output support (enabled with SHADER_TRANSLATOR_ENABLE_HLSL)
• DXC (DirectX Shader Compiler): HLSL input support (enabled with SHADER_TRANSLATOR_ENABLE_HLSL_INPUT)
  • Available in VulkanSDK 1.3.216+

Usage

Unified Shader Compiler (Recommended)

#include <shadertranslator/shader_translator.h>

using namespace ShaderTranslator;

// Create unified compiler
ShaderCompiler compiler;

// Example 1: Compile GLSL vertex shader to MSL
std::string glslVertex = R"(
    #version 450
    layout(location = 0) in vec3 position;
    layout(location = 1) in vec2 texCoord;

    void main() {
        gl_Position = vec4(position, 1.0);
    }
)";

auto result = compiler.CompileGLSL(
    glslVertex,
    ShaderStage::Vertex,
    TargetLanguage::MSL,
    PlatformVersion{ .metalVersion = 22 }  // Metal 2.2
);

if (result.success) {
    std::string mslCode = result.source;
    // Use with MTLDevice newLibraryWithSource:
}

// Example 2: Compile GLSL to HLSL with defines
std::vector<std::string> defines = { "USE_TEXTURES", "SHADOW_QUALITY 2" };
auto hlslResult = compiler.CompileGLSL(
    glslVertex,
    ShaderStage::Vertex,
    TargetLanguage::HLSL,
    PlatformVersion{ .hlslShaderModel = 60 },
    defines
);

// Example 3: Cache SPIR-V for faster recompilation
compiler.CompileGLSL(glslVertex, ShaderStage::Vertex, TargetLanguage::SPIRV);
std::vector<uint32_t> cachedSPIRV = compiler.GetLastSPIRV();
// Save to disk, then later:
SPIRVTranslator translator;
auto fastResult = translator.TranslateToMSL(cachedSPIRV, 22);

Low-Level SPIR-V Translation

// If you already have SPIR-V bytecode
SPIRVTranslator translator;
std::vector<uint32_t> spirvBytecode = /* ... */;

auto result = translator.TranslateToMSL(spirvBytecode, 22);  // Metal 2.2

Integration

ShaderTranslator is designed to be library-agnostic and can be used standalone or integrated into larger projects. It uses SPIRV-Cross and glslang from the ZVulkan library directory but is built as a separate library.

License

Same as GZDoom (GPL with additional permissions - see parent LICENSE files)

Architecture

ShaderTranslator/
├── include/shadertranslator/
│   └── shader_translator.h    # Public API
├── src/
│   └── spirv_translator.cpp   # SPIRV-Cross wrapper implementation
├── CMakeLists.txt             # Build configuration
└── README.md                  # This file

The library relies on glslang and SPIRV-Cross from ../ZVulkan/src/ but is built independently.

Metal Version Support

Metal Version	macOS Version	Features
2.0	10.13+	Base Metal 2 support
2.1	10.14+	Additional features
2.2	10.15+	More features
2.3	11.0+	Advanced features
2.4	12.0+	Latest features

Contributing

When modifying ShaderTranslator:

1. Maintain compatibility with the public API in shader_translator.h
2. Keep the library focused on translation only
3. Test with both MSL and HLSL outputs (if HLSL enabled)
4. Update this README for any API changes