XShaderCompiler ("Cross Shader Compiler")

Features

• Cross compiles HLSL shader code (Shader Model 4 and 5) into GLSL
• Simple to integrate into other projects
• Low overhead translation (i.e. avoidance of unnecessary wrapper functions)
• Dead code removal
• Code reflection
• Meaningful report output
• Commentary preserving
• Written in C++11

Language Bindings

• C Wrapper (ISO C99)
• C# Wrapper

License

3-Clause BSD License

Documentation

• Getting Started with XShaderCompiler (PDF)
• XShaderCompiler Reference Manual (PDF)

Progress

Version: 0.11 Alpha (Do not use in production code!)

See the TODO.md file for more information.

Feature	Progress	Remarks
Vertex Shader	~80%	Few language features are still left
Tessellation Control Shader	~20%	InputPatch and patch-constant-function translation in progress
Tessellation Evaluation Shader	~20%	OutputPatch translation in progress
Geometry Shader	~60%	Code generation is incomplete
Fragment Shader	~80%	Few language features are still left
Compute Shader	~80%	Few language features are still left

Offline Compiler

The following command line translates the "Example.hlsl" file with the vertex shader entry point "VS", and the fragment shader entry point "PS":

xsc -E VS -T vert Example.hlsl -E PS -T frag Example.hlsl

The result are two GLSL shader files: "Example.VS.vert" and "Example.PS.frag".

Library Usage (C++)

#include <Xsc/Xsc.h>
#include <fstream>
#include <iostream>

int main()
{
    // Input file stream (use std::stringstream for in-code shaders).
    auto inputStream = std::make_shared<std::ifstream>("Example.hlsl");

    // Output file stream (GLSL vertex shader)
    std::ofstream outputStream("Example.VS.vert");

    // Fill the shader input descriptor structure
    Xsc::ShaderInput inputDesc;
    inputDesc.sourceCode     = inputStream;
    inputDesc.shaderVersion  = Xsc::InputShaderVersion::HLSL5;
    inputDesc.entryPoint     = "VS";
    inputDesc.shaderTarget   = Xsc::ShaderTarget::VertexShader;

    // Fill the shader output descriptor structure
    // Use outputDesc.options, outputDesc.formatting, and outputDesc.nameMangling for more settings
    Xsc::ShaderOutput outputDesc;
    outputDesc.sourceCode = &outputStream;

    // Optional output log (can also be a custom class)
    Xsc::StdLog log;

    // Optional shader reflection data (for shader code feedback)
    Xsc::Reflection::ReflectionData reflectData;

    // Translate HLSL code into GLSL
    try
    {
        bool result = Xsc::CompileShader(inputDesc, outputDesc, &log, &reflectData);
    }
    catch (const std::exception& e)
    {
        std::cerr << e.what() << std::endl;
    }

    return 0;
}

Library Usage (C#)

using System;
using System.IO;

namespace Example
{
    class Program
    {
        static void Main()
        {
            // Create instance of the XShaderCompiler
            var compiler = new XscCompiler();

            // Fill the shader input descriptor structure
            var inputDesc = new XscCompiler.ShaderInput();
            inputDesc.SourceCode     = File.ReadAllText("Example.hlsl");
            inputDesc.ShaderVersion  = XscCompiler.InputShaderVersion.HLSL5;
            inputDesc.EntryPoint     = "VS";
            inputDesc.Target         = XscCompiler.ShaderTarget.VertexShader;

            // Fill the shader output descriptor structure
            // Use outputDesc.Options, outputDesc.Formatting, and outputDesc.MameMangling for more settings
            var outputDesc = new XscCompiler.ShaderOutput();

            // Optional output log (can also be a custom class)
            var log = compiler.StandardLog;

            // Optional shader reflection data (for shader code feedback)
            var reflectData = new XscCompiler.ReflectionData();

            // Translate HLSL code into GLSL
            try
            {
                bool result = compiler.CompileShader(inputDesc, outputDesc, log, reflectData);

                if (result)
                {
                    // Write output shader code
                    File.WriteAllText("Example.VS.vert", outputDesc.SourceCode);
                }
            }
            catch (Exception e)
            {
                Console.WriteLine(e);
            }
        }
    }
}

Real-time Debugger

A real-time debugger with UI is provided. Although this debugger is mainly used for developement of the compiler itself, it can also be used for a quick translation overview, to see how language constructs are being cross compiled.

Example of the real-time debugger (requires wxWidgets 3.1.0 or later):

Language Differences

Here is a brief outline of High-Level differences between HLSL and GLSL, which XShaderCompiler is able to translate properly:

Feature	HLSL	GLSL
Separation of Textures and Samplers	Yes	Only for Vulkan
Structure Inheritance	Yes	No
Nested Structures	Yes	No
Anonymous Structures	Yes	No
Structure Member Functions	Yes	No
Default Parameters	Yes	No
Object-Oriented Intrinsics	Yes	No
Multiple Entry Points	Yes	No
Type Aliasing	Yes	No
L-Values of Input Semantics	Yes	No
Implicit Type Conversion	Extensive	Restricted