Headless mode

Headless mode runs the engine without a window or rendering. Systems and networking still tick, which is how the multiplayer server runs.

Enabling

Set config.headless = true:

Engine::ApplicationConfig config;
config.headless = true;
Engine::Application app(config);
app.Run();

Or pass --headless to a generated game, which MultiplayerPlugin reads from the launch options.

What changes

• InitWindow is not called; no OpenGL context is created.
• VirtualResolution is not registered, so there is no canvas.
• PostUpdate returns immediately: no rendering, no onUI.
• PreUpdate skips virtual-canvas scaling and mouse mapping, but still polls input.
• Update runs every registered system in order, including ScriptSystem and MultiplayerSystem.

What stays the same

• The fixed timestep loop and dt.
• Component, system, and resource registration.
• Scene loading through SceneManager.
• Networking: the server host is created and polls every tick.

Use cases

• Dedicated multiplayer servers (Game --server --headless).
• Automated tests that exercise gameplay without a window.
• Batch processing or headless simulation.

Caveats

• Systems that assume a window (rendering, ImGui) must guard with HasResource<VirtualResolution>().
• GetGameTexture() throws ErrorEcs in headless mode because the resource is missing.
• Audio may still open a device; disable it by skipping AudioPlugin::Init() if you do not need sound on a server.