# port.ludic - what the things ask the game. Every member has a default: unbound, the ground is at
# 0, nothing is drawn, and the save keeps what its kind says to keep.
export port ThingsWorld {
  ground: fn(float, float) -> float = fn th_flat      # the height a moved Thing stands at
  placed: fn(Thing) -> void = fn th_nothing           # a Thing exists now: draw it
  removed: fn(Thing) -> void = fn th_nothing          # it is gone for good: stop drawing it
  shown: fn(Thing) -> void = fn th_nothing            # its `active` changed: show or hide it
  restocks: fn(float, float) -> bool = fn th_yes2      # a morning restocks here (inside a zone)
  moved: fn(Thing) -> void = fn th_nothing            # it stands somewhere else now
  keeps: fn(Thing) -> bool = fn th_kind_saves         # the save's section carries it
  put_down: fn(Thing) -> bool = fn th_kind_put_down   # set down by someone: a restock leaves it be
  restored: fn(Thing) -> void = fn th_nothing         # a load put it back (after `placed`)
}
function th_flat(x: float, z: float) -> float { return 0.0 }
function th_nothing(t: Thing) -> void { }
function th_yes2(x: float, z: float) -> bool { return true }
function th_kind_saves(t: Thing) -> bool { return thing_kind_ok(t.kind) and ThingKinds[t.kind].saved }
function th_kind_put_down(t: Thing) -> bool { return thing_kind_ok(t.kind) and ThingKinds[t.kind].put_down }