ludic/packages/ludic.things/queries.ludic

# queries.ludic - where the Things are. Only active Things answer, except thing_by_uid and
# things_each_all, which ask about everything that exists. A kind below 0 is any kind.
function th_of(t: Thing, kind: int) -> bool { return kind < 0 or t.kind == kind }

# the first active one of a kind (and of that id, unless id < 0), in the order placed
export function thing_find(things_st: mut ThingsState, kind: int, id: int) -> Thing {
  let all = things_all(things_st)
  for i in 0 .. len(all) {
    let t = all[i]
    if t.active and th_of(t, kind) and (id < 0 or t.id == id) { return t }
  }
  return null
}

export function thing_by_uid(things_st: mut ThingsState, uid: int) -> Thing {
  let all = things_all(things_st)
  for i in 0 .. len(all) { if all[i].uid == uid { return all[i] } }
  return null
}

# the nearest active one of a kind to (x, z), or null
export function thing_nearest(things_st: mut ThingsState, kind: int, x: float, z: float) -> Thing {
  var best: Thing = null
  var bd = 0.0
  let all = things_all(things_st)
  for i in 0 .. len(all) {
    let t = all[i]
    if not t.active or not th_of(t, kind) { continue }
    let d = thing_dist2(t, x, z)
    if best == null or d < bd {
      best = t
      bd = d
    }
  }
  return best
}

# the squared ground distance from a Thing to (x, z)
export function thing_dist2(t: Thing, x: float, z: float) -> float {
  let dx = t.x - x
  let dz = t.z - z
  return dx * dx + dz * dz
}

# every active one within r of (x, z), nearest first
export function things_within(things_st: mut ThingsState, x: float, z: float, r: float) -> []Thing {
  let out = new []Thing
  let all = things_all(things_st)
  for i in 0 .. len(all) {
    let t = all[i]
    if t.active and thing_dist2(t, x, z) <= r * r { th_insert(out, t, x, z) }
  }
  return out
}

function th_insert(out: []Thing, t: Thing, x: float, z: float) -> void {
  push(out, t)
  var j = len(out) - 1
  while j > 0 and thing_dist2(out[j - 1], x, z) > thing_dist2(t, x, z) {
    out[j] = out[j - 1]
    j -= 1
  }
  out[j] = t
}

# every active one of a kind, in the order placed
export function things_each(things_st: mut ThingsState, kind: int) -> []Thing {
  let out = new []Thing
  let all = things_all(things_st)
  for i in 0 .. len(all) { if all[i].active and th_of(all[i], kind) { push(out, all[i]) } }
  return out
}

# every one of a kind, active or not
export function things_each_all(things_st: mut ThingsState, kind: int) -> []Thing {
  let out = new []Thing
  let all = things_all(things_st)
  for i in 0 .. len(all) { if th_of(all[i], kind) { push(out, all[i]) } }
  return out
}