Settings Storage

Trial offers a standardised way to store and access user settings for your game. The settings are stored as a nested tree of plists.

Using Settings

Setting the default properties of the settings works simply by setfing +settings+:

(setf +settings+
      (copy-tree '(:audio (:latency 0.005
                           :backend :default
                           :device :default
                           :volume (:master 0.5
                                    :effect 1.0
                                    :music 1.0))
                   :display (:resolution (T T)
                             :fullscreen T
                             :vsync T
                             :target-framerate :none
                             :gamma 2.2
                             :ui-scale 1.0)
                   :gameplay (:rumble 1.0
                              :screen-shake 1.0)
                   :language :system)))

When you save-settings this plist structure is output to a local file appropriate for your game, provided +app-system+ and +app-vendor+ are correctly set (see config-directory).

When you load-settings the plist is read from the file and merged with the existing settings. This means missing keys are augmented, existing keys are overwritten, and superfluous keys are retained.

Accessing settings happens through the setting function, which takes a path to the value you want to access. When you update a setting through this function, it similarly merges things, adding and overwriting keys as necessary. Reading settings out with this function should be very fast provided that the setting compiler-macro can be expanded (so not called through funcall, not declared notinline).

Often it is also useful to react in various parts of the game when a setting is changed. To install change hooks, use define-setting-observer:

(define-setting-observer update-resolution :display :resolution (value)
  (when *context*
    (show *context* :fullscreen (setting :display :fullscreen) :mode value)))

Standard Fields

Trial defines the following setting paths as standard. It will integrate better if you structure your settings in the same way.

Audio

Settings related to audio playback. See audio.mess

• :audio :latency The size of the internal audio buffers in seconds. Should default to a very low value

• :audio :backend The audio backend chosen for playback. Should always be :default

• :audio :device The audio device used by the chosen backend. The values are backend-specific, but should default to :default

• :audio :volume .. Volume values for various segments in the audio pipeline. Should include the volumes for the mixers, in the very least

Display

Settings related to graphics and context. See context.mess

• :display :resolution A video mode description: (width height [refresh rate [monitor identifier string]]). Should default to (T T)

• :display :fullscreen Whether the game should be in fullscreen mode. Should default to T

• :display :vsync Whether vertical sync should be active. Should default to T

• :display :target-framerate What framerate should be targeted (frame throttle). Should default to NIL

• :display :gamma The gamma value by which to map from HDR to SDR. Should default to 2.2

• :display :ui-scale The base scaling of all UI elements. Should default to 1.0

• :display :texture :filter The texture filtering to use. Can be one of :nearest :linear :trilinear. Should default to :trilinear.

• :display :texture :anisotropy The anisotropic filtering level to use. Can be any power of two. Should default to 2.

Gameplay

General gameplay options and tweaks for the user.

• :gameplay :camera-shake A float scaling the intensity of camera shaking. Should default to 1.0

• :gameplay :rumble A float scaling the intensity of gamepad rumble. Should default to 1.0

• :gameplay :fov The field-of-view variable for perspective cameras

Language

The language to use. See localization.mess

• :language The language used for the game. Should be a standard language code string or :system. Should default to :system

Debugging

Debugging options for diagnostics.

• :debugging :swank Whether to start a swank server, and if so, on what port

• :debugging :fps-counter Whether to show an fps-counter

Keymaps

See input.mess

Loading and saving the keymap.lisp file can be conveniently done through load-keymap and save-keymap. When load-keymap is called, it will check whether the keymap.lisp file in the root is newer, and if so, update the old one. This ensures that changes to the actions or keymaps will propagate to installations that already have a potentially stale map.