How to make game window transparent using opacity from camera

Development Programming & Scripting C++
,
3

:video_game: How to Make a Game Window Transparent Using Camera Opacity

:white_check_mark: 1. Unity (C#)

If you’re using Unity, you can adjust the Camera’s background and alpha to make the game window partially or fully transparent:

Steps:

  1. Set the camera background color alpha to 0:

    Camera.main.clearFlags = CameraClearFlags.SolidColor;
Camera.main.backgroundColor = new Color(0, 0, 0, 0); // RGBA (0 alpha)

  2. Enable transparency in the build:

    • Go to Project Settings → Player.

    • Under Windows → Resolution and Presentation, enable:

      • Allow Transparency (only works with certain settings)

    • Set the rendering mode to use alpha (in URP or HDRP).

  3. Use a transparent shader or materials in your scene as needed.

  4. Note: This might only work in Windowed mode and may require special window flags (see below).

:white_check_mark: 2. SDL2 (C++ or Python)

For simpler 2D games using SDL2:

SDL_SetWindowOpacity(window, 0.5f); // 50% transparent

Make sure to:

  • Use a window with the SDL_WINDOW_ALWAYS_ON_TOP | SDL_WINDOW_BORDERLESS flags.
  • This works on platforms like Windows and Linux with proper backend support.

:white_check_mark: 3. Win32 API (C++)

If you are making your game with native Win32:

SetWindowLong(hwnd, GWL_EXSTYLE,
    GetWindowLong(hwnd, GWL_EXSTYLE) | WS_EX_LAYERED);
SetLayeredWindowAttributes(hwnd, 0, 128, LWA_ALPHA); // 128 = 50% opacity

:smiley: