Integrate Unity into Windows applications

You can use the Unity as a Library feature to integrate the Unity Runtime Library in Windows applications.

This feature enables you to include Unity-powered features in your application, such as:

• 3D/2D Real-Time Rendering
• AR Experience
• 3D model interaction
• 2D mini-games

The Unity Runtime Library exposes controls to manage when and how to load, activate, and unload content within the application.

On Windows, you can embed a Unity build into your application in the following ways:

• Launch Unity as an external build - This is the easier option.
• Embed Unity within your existing operating system process

Launch Unity as an external build

You can launch Unity as an external build from your application and specify a window in which Unity will initialize and render with the -parentHWND 'HWND' delayed command line argument.

When you pass -parentHWND 'HWND' delayed, the Unity application hides while the command runs. To successfully embed the window, you must:

For an example of a Unity application embedded in a window, refer to the EmbeddedWindow downloadable example.

Resize the window

To resize the Unity window, check its GWLP_USERDATA in Microsoft’s GetWindowLongPtr function:

• Its lowest bit is set to 1 when the graphics initialize and it’s safe to resize.
• Its second lowest bit is set to 1 after the Unity splash screen finishes displaying.

Embed Unity within your existing operating system process

To embed Unity within your existing operating system process:

1. Load UnityPlayer.dll directly into your Win32 application.

2. Call the UnityMain entry point with the following signature:

   extern "C" int UnityMain2(HINSTANCE hInst, LPCWSTR customDataFolder, LPWSTR szCmdLine, int nCmdShow);
   

3. Pass command line arguments to Unity via the lpCmdLine parameter. You can use this to control settings such as resolution, job threads, or the parent HWND.

For a full list of valid arguments you can pass to lpCmdLine, refer to the Unity Standalone Player command line arguments documentation.

Additional resources

• Using Unity as a Library in other applications
• Unity Standalone Player command line arguments