How to create multiple consecutive commands with ECSx?

Elixir Framework Forums ECSx Forum
1

Hello, a question, participating in the ECSx (Ship) tutorial, but changing the dynamics of the game. How multiple consecutive commands of the following line should be implemented in the code:

  ECSx.ClientEvents.add(socket.assigns.player_entity, event)

For the purposes of managing both the movements and firing of the ship via orders entered with types from the interface?

Ex.

“move north 10 positions”, “launch 3 shots”, “move west 5 positions”

I’ll look forward for your answer!

1 Like
2

Hi Miguel! When using ClientEvents, try to make each event line up with a single input from the user. So, let’s say you have a button which can be clicked by the user to move north, and one button click always equals 10 “positions” on the map. The ClientEvent in this case would just be :move_north - and the distance moved is only a concern for the ClientEventHandler:

def Ship.Systems.ClientEventHandler do
  ...
  @move_distance 10

  defp process_one({player, :move_north}) do
    y = YPosition.get(player)
    YPosition.update(player, y + @move_distance)
  end
end

Now, if you have a button where sometimes a press moves 10 positions, and other times a press moves 5 positions, the question is: what determines this value? If the value comes from the frontend, such as a slider in the UI where the user adjusts the speed, then we’ll attach that value as metadata with the event:

ClientEvents.add(player_entity, {:move_north, 10})
ClientEvents.add(player_entity, {:move_north, 5})

and the handler:

defp process_one({player, {:move_north, value}}) do
  y = YPosition.get(player)
  YPosition.update(player, y + value)
end

But if the value is based in the backend (stored as a component somewhere) then metadata should not be used. For example, if one button press equals s positions, where s is the SailingSpeed of the player’s ship, simply add :move_north and fetch the value in the handler:

defp process_one({player, :move_north}) do
  y = YPosition.get(player)
  value = SailingSpeed.get(player)
  YPosition.update(player, y + value)
end

Hope this helps, happy to answer any other questions you might have!

1 Like
3

Hi Andy, I appreciate the quick response, you surprised me!
I understood the concept perfectly. However, I don’t see a way to change the dynamic, I want to implement multiple actions concatenated from a simple user event, for example with a text input.
I think the problem is in the update cycle between the frontend and backend.
Any ideas you can give me will be welcome!
Thank you in advance…

4

Remember, you want one ClientEvent for each user event. In this case we have:

  • 1 simple user event on the frontend
def handle_event("liveview_event", params, socket) do
  ...
  ECSx.ClientEvents.add(player_entity, {:simple_user_event, maybe_metadata})
  ...
end
  • multiple actions on the backend
def Ship.Systems.ClientEventHandler do
  ...

  defp process_one({player, :simple_user_action, metadata}) do
    do_action_1()
    do_action_2()
    do_action_3()
    ...
  end
end
5

Great Andy, this works! Now, to up level, any idea to aggregate sound?
I hope your comments! Thank you from yet!

6

Playing audio is mostly a job for the client - so it depends on what type of frontend you are using. If it’s a web game in the browser, maybe start with looking into Using the Web Audio API - Web APIs | MDN

7

Ok, let’s go for this! Thank you very much!