ryuko

ryuko(流光, meaning "flowing light") is a transpiler from a custom shader language to GLSL.

Features

1. Shader Parsing

   Parses GLSL code to extract functions and varyings.

2. Transformation

   Modifies main shader functions' return values, ensuring compatibility with Vulkan requirements:

   • Vertex shader: vert()'s return expression is converted into assignment to gl_Position.
   • Fragment shader: frag()'s return expression is assigned to a custom out variable.

3. GLSL Code Emission

   Transpiles and emits modified vertex and fragment shader code to separate GLSL files.

4. Error Handling

   Provides detailed error messages with formatted outputs for easier debugging.

Getting Started

Prerequisites

• C++ Compiler: Requires a compiler that supports C++20.
• Libraries:
  • fmt: For formatted text output.
• CMake: Building the project.
• mei: Building the project.

⚠️ Requires the fmt xrepo package to be installed. It can be installed with:

xrepo install -y fmt

Compilation

Clone the repository:

git clone https://github.com/straightcurve/ryuko.git
cd ryuko

Generate CMakeLists.txt

npx @sweetacid/mei

Create a build directory:

mkdir build && cd build

Configure and build:

cmake ..
make

Code Structure

Parser

Extracts functions, varyings and shader version.

Transpiler

Modifies shader code to align with Vulkan requirements:

• Rewrites return statements into appropriate assignments.
• Adds varying variable declarations when necessary.

Emitter

Responsible for emitting the final GLSL code:

• Ensures functions are emitted in dependency order.
• Handles GLSL version declarations and varying declarations.

Main Functionality (transpile)

Orchestrates the parsing, transpiling and emission of shaders.

Example Input/Output

Input Shader:

#version 450

varying vec4 Position;
varying vec4 Color;

vec4 vert() {
    Color = vec4(Position.zyx, 1.0);

    return vec4(Position.xyz, 1.0);
}

vec4 frag() {
    return Color;
}

Output Vertex Shader:

#version 450

layout (location = 0) in vec4 Position;
layout (location = 0) out vec4 Color;

void main() {
    Color = vec4(Position.zyx, 1.0);
    gl_Position = vec4(Position.xyz, 1.0);
}

Output Fragment Shader:

#version 450

layout (location = 0) in vec4 Color;
layout (location = 0) out vec4 ryuko_outColor;

void main() {
    ryuko_outColor = Color;
}

Error Handling

Reports errors such as:

• Missing vertex or fragment main functions.
• Invalid GLSL syntax (partial).
• Parsing failures due to unsupported constructs.

License

This project is licensed under the MIT License. See the LICENSE file for details.

Contributing

Contributions are welcome! Feel free to submit issues or pull requests for bug fixes, enhancements, or additional features.