ludic/examples/events/layer_events.ludic

# layer_events.ludic — EV1 for layers + SCENES E2 (layer toggle). A `public` layer
# promotes its show/hide to events; `enable layer L` / `disable layer L` flips the
# layer on and off (its handlers stop running while hidden) and fires
# layer_<L>_show / layer_<L>_hide. This closes the last scope of "events across the
# whole architecture" — properties, models, scenes, program, and now layers.
#
# Running it prints:  50 2 1 50
program LayerEvents {
  state LayerEventsState {
    step: int = 0
  }

  @On(layer_Hud_show) handler Shown  { print(1) }   # a mod reacts when the HUD returns
  @On(layer_Hud_hide) handler Hidden { print(2) }   # ...and when it's hidden

  scene Main start {
    layer Hud public {
      handler Draw phase Update { print(50) }        # only runs while Hud is enabled
    }
    layer Ctrl {
      handler Drive(layer_events_st: mut LayerEventsState) phase LateUpdate {
        layer_events_st.step += 1
        if layer_events_st.step == 1 { disable layer Hud }           # frame 1: hide -> Hidden 2, Draw stops
        if layer_events_st.step == 2 { enable layer Hud }            # frame 2: show -> Shown 1, Draw resumes
        if layer_events_st.step == 3 { quit() }                      # frame 3: after Draw ran again
      }
    }
  }
}