RedNoise Python bindings

Python ctypes bindings for the RedNoise CPU software renderer. They call the stable C ABI declared in include/rednoise/rednoise.h. There is no compiled extension module: the bindings load the RedNoise shared library at runtime. The native library is built and bundled into the package, so a normal install is self-contained.

Install

pip install rednoise

Prebuilt wheels ship the native library, so on a supported platform this is all you need. Installing from an sdist compiles the native library on your machine via CMake, so you need a C++23-capable compiler (GCC 12+, Clang 15+, or MSVC 2022+) and CMake 3.24 or newer. The build uses the vendored glm in third_party/ and runs fully offline; it does not fetch SDL3 or any other optional dependency.

Under the hood, pip install drives scikit-build-core and CMake to build only the installable rednoise library (-DBUILD_LIB=ON, everything else off) and installs the resulting shared library into the importable rednoise/ package:

• Linux: librednoise.so
• macOS: librednoise.dylib
• Windows: rednoise.dll

Pillow is optional and only needed for Image.to_pillow() or saving non-PNG formats:

pip install "rednoise[pillow]"

Library discovery

The bundled library is found automatically. For development against a separately built library, the bindings locate it in this order:

1. The library bundled next to the package (what a wheel installs).
2. The REDNOISE_LIBRARY environment variable (an explicit path to the file).
3. The system search path (ctypes.util.find_library("rednoise")).
4. Common local build paths (build/, next to the package, and similar).

To override with a locally built library, set REDNOISE_LIBRARY:

# Linux
export REDNOISE_LIBRARY="$PWD/build/librednoise.so"

# macOS
export REDNOISE_LIBRARY="$PWD/build/librednoise.dylib"

# Windows (cmd)
set REDNOISE_LIBRARY=%CD%\build\rednoise.dll

Develop from a local checkout

Install the bindings straight from this directory:

pip install ./bindings/python

Add the Pillow extra with:

pip install "./bindings/python[pillow]"

You can still build the shared library by hand from the repository root and point REDNOISE_LIBRARY at it:

cmake -B build -S . -DBUILD_LIB=ON -DBUILD_APP=OFF
cmake --build build

Usage

import rednoise

print(rednoise.version())

with rednoise.Scene.load_obj("assets/cornell-box.obj") as scene:
    print("triangles:", scene.triangle_count)
    image = scene.render(mode="pathtraced", width=400, height=300, samples=64)
    image.save("cornell.png")

Scene.render accepts a render mode as a RenderMode enum, an integer, or a name string: "wireframe", "rasterised", "raytraced", or "pathtraced". The returned Image exposes .rgba (raw RGBA8 bytes), .size, .save(path), and .to_pillow() when Pillow is installed.

A complete runnable example lives in example.py. Run it from the repository root (after building the library and setting REDNOISE_LIBRARY):

python bindings/python/example.py