Sharing logic between systems

Hi,

I'm new to the ECS pattern, and I kind of block on how I could achieve what I want.
I have a PlayerActionSystem that when an Input is register, will check if there is a tile that will collide over the next move, if not, the player do a move.
Looks like that:

Code (CSharp):

1.  public class PlayerActionSystem : ComponentSystem
2.     {
3.         [Inject] public PlayersGroupData PlayersGroup;
4.         [Inject] public ObstaclesGroupData ObstaclesGroup;
5.  
6.         protected override void OnUpdate()
7.         {
8.             if (PlayersGroup.Length == 0)
9.             {
10.                 return;
11.             }
12.  
13.             for (var i = 0; i < PlayersGroup.Length; ++i)
14.             {
15.                 var playerInput = PlayersGroup.Inputs[i];
16.  
17.                 var targetPosition = PlayersGroup.GridPositions[i];
18.  
19.  
20.                 if (playerInput.MoveX != 0 || playerInput.MoveY != 0)
21.                 {
22.                     targetPosition.Value.x += playerInput.MoveX;
23.                     targetPosition.Value.y += playerInput.MoveY;
24.  
25.  
26.                     //Check Collision
27.                     Entity obstacle = Entity.Null;
28.                    
29.                     if (ObstaclesGroup.Length > 0)
30.                     {
31.                         for (int j = 0; j < ObstaclesGroup.Length; j++)
32.                         {
33.                             if (ObstaclesGroup.GridPositions[j].Value == targetPosition.Value)
34.                             {
35.                                 obstacle = ObstaclesGroup.Entities[j];
36.                                 break;
37.                             }
38.                         }
39.                     }
40.                    
41.                     if (obstacle.Equals(Entity.Null))
42.                     {
43.                         //Move
44.                         PostUpdateCommands.AddComponent(PlayersGroup.Entities[i], new MoveToTarget(targetPosition.Value));
45.                     }
46.                     else
47.                     {
48.                         //Do Damage
49.                         if (EntityManager.HasComponent<Health>(obstacle))
50.                         {
51.                             PostUpdateCommands.AddComponent(obstacle, new DoDamage(1));
52.                             PostUpdateCommands.AddSharedComponent(PlayersGroup.Entities[i], new TriggerAnimation("playerChop"));
53.                         }
54.                         //Move
55.                         if (EntityManager.HasComponent<FoodTag>(obstacle))
56.                         {
57.                             PostUpdateCommands.AddComponent(PlayersGroup.Entities[i], new MoveToTarget(targetPosition.Value));
58.                         }
59.                     }
60.                     PostUpdateCommands.AddComponent(PlayersGroup.Entities[i], new HasPlayTurn());
61.                 }
62.             }
63.         }
64.  
65.         public struct PlayersGroupData
66.         {
67.             public int Length;
68.             public EntityArray Entities;
69.             public ComponentDataArray<GridPosition> GridPositions;
70.             [ReadOnly] public ComponentDataArray<PlayerInput> Inputs;
71.             [ReadOnly] public SubtractiveComponent<MoveToTarget> MoveToTarget;
72.             [ReadOnly] public ComponentDataArray<TurnBasedTag> TurnBased;
73.             [ReadOnly] public ComponentDataArray<IsActiveTurn> IsActiveTurn;
74.             [ReadOnly] public SubtractiveComponent<HasPlayTurn> HasPlayTurn;
75.         }
76.  
77.         public struct ObstaclesGroupData
78.         {
79.             public int Length;
80.             public EntityArray Entities;
81.             [ReadOnly]
82.             public ComponentDataArray<GridPosition> GridPositions;
83.             [ReadOnly]
84.             public ComponentDataArray<BoardObstacle> BoardObstacle;
85.         }
86.     }

The thing is that, I also want my EnemyAISystem to check for collision before they could move.
Since I can access entities through Inject, I would have to inject and reproduce the same code in my EnemyAISystem which doesn't seem very efficient.

How would you go to share "global" logic like that between systems ?

Thanks

 

Thanks Joachim,

I understand why you are saying and I though about that, but I would still need to inject those results in to each system, which I'm not a huge fan.

Also in this scenario I don't really need collisions events, I just need my AI to be aware of his surrounding to select the right action to do.

The best scenario I could think of, is kind of a static function, that will return tiles around the targeted entities, but since systems runs OnUpdate, you can't really call a function like that and get the result right away.

EDIT: Btw I'm trying to convert RogueLike2D to ECS, and trying to seperate systems to best I can, for them to be reusable

 

Don't move your ai and player in the specific systems directly. Just set a "PrepairMovement" component at this point and handle the real movement in a 3rd system that handles the collision too.
Maybe this approach will help you...

 

Thanks for the answer.
I will think about that, maybe it is the solution to add a new system inbetween.