Safi Engine

    Resources (Singletons)

    flecs doesn't have a dedicated "resource" concept the way Bevy does — it uses singleton components instead. A singleton is just a component set on the world entity itself. The API is slightly different from regular components but the concept is identical.

    Built-in singletons

    SingletonDescriptionWritten by
    SafiTimeper-frame delta, elapsed, frame idxsafi_app_tick
    SafiInputkeyboard + mouse snapshotsafi_input_pump

    Reading

    const SafiInput *in = ecs_singleton_get(world, SafiInput);
if (in->keys[SDL_SCANCODE_SPACE]) { /* jump */ }

    Writing (for your own resources)

    typedef struct GameSettings { float master_volume; bool debug_draw; } GameSettings;
ECS_COMPONENT_DEFINE(world, GameSettings);

ecs_singleton_set(world, GameSettings, { .master_volume = 0.8f, .debug_draw = true });

// later...
GameSettings *g = ecs_singleton_ensure(world, GameSettings);
g->debug_draw = !g->debug_draw;
ecs_singleton_modified(world, GameSettings);

    Querying a singleton from inside a system

    flecs will auto-inject it if you tag the term as singleton:

    ecs_system(world, {
    .entity = ecs_entity(world, { .name = "audio_system", .add = ecs_ids(ecs_dependson(EcsOnUpdate)) }),
    .query.terms = {
        { .id = ecs_id(SafiTransform) },
        { .id = ecs_id(GameSettings), .src.id = ecs_id(GameSettings) }, // singleton term
    },
    .callback = audio_system,
});

    See also