ludic/packages/ludic.session/near.ludic

# near.ludic - the world asks who is nearest, never "the player": an animal notices whoever is
# closest, a camper keeps clear of everyone
export function ply_near_d2(session_st: mut SessionState, x: float, z: float) -> float {
  session_st.session__near_i = 0
  var best = 0.0
  var first = true
  for p in 0 .. PLY_MAX {
    if not ply_on(session_st, p) { continue }
    let dx = x - ply_x(session_st, p)
    let dz = z - ply_z(session_st, p)
    let d2 = dx * dx + dz * dz
    if first or d2 < best {
      best = d2
      session_st.session__near_i = p
      first = false
    }
  }
  return best
}

# the distance to the nearest player, in metres; ply_near_i() says which
export function ply_near(session_st: mut SessionState, x: float, z: float) -> float { return Math.sqrt(ply_near_d2(session_st, x, z)) }

export function ply_near_i(session_st: SessionState) -> int { return session_st.session__near_i }

export function ply_dist(session_st: SessionState, p: int, x: float, z: float) -> float {
  let dx = x - ply_x(session_st, p)
  let dz = z - ply_z(session_st, p)
  return Math.sqrt(dx * dx + dz * dz)
}