ludic/examples/hello.ludic

# hello.ludic — smallest program that exercises the ECS pipeline
game Hello {

  component Pos { x: int = 0, y: int = 0 }
  component Vel { dx: int = 0, dy: int = 0 }

  system Boot phase Start {
    spawn Mob {
      Pos { x: 3, y: 4 }
      Vel { dx: 1, dy: 0 }
    }
    spawn Mob {
      Pos { x: 10, y: 2 }
      Vel { dx: 0, dy: 1 }
    }
  }

  # a system can declare the entities it operates on: the body then runs once
  # per match, with the components bound and self() giving that entity.
  system Move phase FixedUpdate
    query (p, v) [Pos, Vel]
  {
    p.x = p.x + v.dx
    p.y = p.y + v.dy
  }

  system Report phase Update {
    for (p) in query [Pos] {
      print_int(p.x)
      print_int(p.y)
    }
    quit()
  }
}