How Emerge draws frames. Set this record as Emerge.Config.renderer; choose where the frames go separately with config.output.

%Emerge.Config{
  output: %Emerge.Config.Headless{target: self()},
  renderer: %Emerge.Config.Renderer{api: :raster, target_fps: 30},
  assets: %Emerge.Config.Assets{otp_app: :my_app}
}

Fields

• api — :auto (default), :raster, :opengl, :vulkan or :metal. Automatic selection uses an available API for the output/build. Raster draws on the CPU; the others use a compatible GPU. Metal is macOS-only; OpenGL and Vulkan are available on supported Linux builds. A config cannot enable an API absent from the installed renderer.
• device — optional absolute DRM device path for Vulkan GPU selection. Defaults to nil. Explicit DRM Vulkan requires a device, independently of the display card in Emerge.Config.DRM.
• raster_present — how CPU-drawn frames reach the output: :auto (default), :cpu or :gpu_upload. Automatic uses CPU presentation on DRM and the backend's normal route elsewhere. GPU upload requires OpenGL support. This setting applies to api: :raster or api: :auto, not an explicit GPU API.
• target_fps — positive integer frame-rate ceiling, or nil (default) for normal backend pacing. It limits drawing, not physical display refresh or application timers. It does not make an idle scene redraw continuously.
• cache — Emerge.Config.RendererCache, controlling reuse of rendered content. Defaults to that record's settings; it is separate from image asset caching.

Changing settings

Only target_fps can change through config, on headless and Wayland outputs. Those outputs also accept it at startup. DRM and macOS do not support frame caps. Changing the API, device, presentation route or cache requires a new viewport.