Handling The Selection Of My Buildings

Folks,

What are you thoughts on this new Job / ECS system for handling the "click" on or selection of an object (in this case a cube) and indicating that object is "selected"? In the old world, you simply attach a monobehavior to the object and handle the method in the "onClick" method.

 

(Note: I also want to handle mouse overs, so your method may differ if you don't)
I define the following components:
MouseOverTarget, MouseOver, ClickTarget, Clicked, ClickHandled

I have the following systems:
MouseOverSystem - goes through all MouseOverTarget entities and adds/removes MouseOver where appropriate
ClickSystem - goes through MouseOver+ClickTarget and adds Clicked if LMB was pressed.

then for each kind of clickable entity in my game I have systems like
CardMouseOverSystem - goes through all Card+MouseOver, (e.g. highlights the card)
CardClickSystem - goes through all Card+Clicked+Not(ClickHandled), does whatever it needs (this is your "OnClick" method) and adds ClickHandled. (For example, in my case it adds a Dragged component for Drag&Drop).

Oh, and the ClickSystem also cleans up Clicked+ClickHandled pairs (just removes them).

I would assume when the ECS matures you will get all but the entity-kind-specific systems built in (just like you don't have to call OnClick yourself in the UI system). Or maybe they will come up with a better method.

 

Hey thank you very much for your response! I will try to implement something like this and wrap my head around this.

 

Question, are you using a RayCast to detect if the mouse is over an object?

 

I'm dealing with rectangles, so I'm using a ray-rectangle test, but I see no reason why a PhysX Raycast wouldn't work (you probably want to use Collider.Raycast instead of Physics.Raycast. I haven't touched the job-friendly physics api yet so can't help there)

 

Well what you have suggested thus far has been a huge help. I am really struggling with thinking the way I need to be thinking to be productive with this new system.

 

Sorry to bother but I have been bouncing around tutorials and the forum for a while now... how are you gaining access to a collider for a given entity? I have this thus far (which I know is incorrect):

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4. using Unity.Entities;
5. using static ComponentTypes;
6. using Unity.Collections;
7.  
8. public class MouseOverSystem : ComponentSystem
9. {
10.    
11.  
12.     public struct MouseOverTargetGroup
13.     {
14.         [ReadOnly] public ComponentDataArray<MouseOverTarget> Targets;
15.         public ComponentDataArray<EntityCollider> Colliders;
16.         public EntityArray Entity;
17.         //public BoxCollider BoxColliders;
18.         public int Length;
19.     }
20.  
21.     [Inject] MouseOverTargetGroup group;
22.     private Ray ray;
23.     private RaycastHit hit;
24.  
25.     protected override void OnUpdate()
26.     {
27.        
28.         ray = Camera.main.ScreenPointToRay(Input.mousePosition);
29.        
30.         for (int i = 0; i < group.Length; i++)
31.         {
32.             //Raycast(ray, out hit, 1000.0f)
33.             //
34.             if (group.Colliders[i].collider.Raycast(ray, out hit, 1000.0f))
35.             {
36.                 Debug.Log("did  I add it?");
37.                 if(!FallenBootstrap.entityManager.HasComponent(group.Entity[i], ComponentType.Create<MouseOver>()))
38.                 {
39.  
40.                     FallenBootstrap.entityManager.AddComponent(group.Entity[i], ComponentType.Create<MouseOver>());
41.                 }
42.             }
43.         }
44.     }
45. }
46.  
47.  

It doesn't matter if I try to add Collider, or BoxCollider, the error is the same. Something about blittable....

 

You cannot store reference type objects (a.k.a. class instances) in IComponentData. All old Unity components are classes, which includes Collider.

The workaround provided is ComponentArray<T> which lets you inject Monobehaviours and old-style built-in components (note, you apparently need a specific type, ComponentArray<Collider> finds nothing for me while ComponentArray<BoxCollider> works).

This works for me:

Code (CSharp):

1. using UnityEngine;
2. using Unity.Entities;
3.  
4. public class RaycastingSystem : ComponentSystem
5. {
6.     struct Data
7.     {
8.         public int Length;
9.         public ComponentArray<BoxCollider> Collider;
10.     }
11.     [Inject] Data _data;
12.  
13.     protected override void OnUpdate()
14.     {
15.         var ray = new Ray(Vector3.zero, Vector3.forward);
16.         for (int i = 0; i < _data.Length; i++)
17.         {
18.             RaycastHit hit;
19.             var collider = _data.Collider[i];
20.             if(collider.Raycast(ray, out hit, Mathf.Infinity))
21.             {
22.                 Debug.Log("Found a thing: " + collider.name);
23.             }
24.         }
25.     }
26. }
27.  

Read on the Hybrid ECS (and look at the Hybrid TwinStickShooter sample) to learn how to set up/spawn GameObjects that will be accessible from Systems (it boils down to attaching GameObjectEntity to an old-style GameObject).