Annoy.NET

Annoy.NET is a cross-platform C# wrapper for Spotify's Annoy. It can be used from Unity and from regular .NET applications through the Annoy.Net NuGet package.

Unity

1. Download annoy.net.unitypackage from the GitHub release assets.
2. Import it into your Unity project.
3. Unity will install the wrapper under Assets/Annoy.NET.
4. The release unitypackage includes the native plugins for Windows, Linux, and macOS.

NuGet

Install the managed wrapper and the platform-specific native library with:

dotnet add package Annoy.Net

The NuGet package ships native assets for win-x64, linux-x64, and osx-x64.

Usage

using System;  
using UnityEngine;  
using AnnoyWrapper;  
  
public class Test : MonoBehaviour  
{  
    void Start()  
    {
        using (var index = Annoy.Index(512, AnnoyMetric.Angular))
        {
            Annoy.AddItem(index, 0, new float[512]);  
            Annoy.AddItem(index, 1, new float[512]);  
            Annoy.AddItem(index, 2, new float[512]);  
            Annoy.Build(index, 10);  
            Debug.Log(Annoy.GetNItems(index)); // 3  
        }
    }}

Project Layout

• dev.trainhead.annoy.net/ contains the Unity-facing package content, samples, and Unity runtime tests.
• src/Annoy.Net/Annoy.Net.csproj exposes the same managed API for non-Unity consumers and produces the Annoy.Net NuGet package.
• tests/Annoy.ManagedSmoke/ contains a cross-platform .NET smoke test that runs against the native library.
• tests/Annoy.NuGetSmoke/ validates the packaged .nupkg through a real PackageReference.

Setup & Build Instructions

1. Clone this repository

git clone https://github.com/TrainHead-software/annoy.net.git
cd annoy.net

2. Clone the Annoy source inside project folder

git clone https://github.com/spotify/annoy.git annoy

3. Build the native library using CMake:

cmake -S annoy_clang -B build -DCMAKE_BUILD_TYPE=Release
cmake --build build --config Release

This produces annoy_c.dll on Windows, libannoy_c.so on Linux , and libannoy_c.dylib on macOS.

4. Run the native and managed smoke tests:

ctest --test-dir build --output-on-failure
dotnet run --project tests/Annoy.ManagedSmoke/Annoy.ManagedSmoke.csproj

5. Build the Unity package locally:

pwsh ./scripts/New-UnityPackage.ps1 -OutputPath ./dist/annoy.net.unitypackage -WindowsLibrary ./build/Release/annoy_c.dll

Add -LinuxLibrary and -MacLibrary when those binaries are available locally. In GitHub Actions, the release workflow injects all native libraries automatically before publishing annoy.net.unitypackage.

6. Build the NuGet package locally:

pwsh ./scripts/New-NuGetPackage.ps1 -OutputDirectory ./dist/nuget -WindowsLibrary ./build/Release/annoy_c.dll

Add -LinuxLibrary and -MacLibrary when those binaries are available locally.

License

This project includes and wraps Spotify Annoy, a C++ library for approximate nearest neighbors.