Handling Events and UI for a turn-based ECS game

Unity Engine
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1

Hey everyone, I’m prototyping a grand strategy game to familiarize myself with ECS. At the end of every turn, I want a group of systems to simulate elements of my population. I followed some tutorials and made a system that listens for a button press via tags. Now I’ve come across two issues:

1. Using burst compile gives me an error: "
…\ProtoPopGrowthSystem.cs(13,9): Burst error BC1025: Accessing the type ProtoPopCalTag (e.g. using typeof) is not supported" Is there a way to rectify a UI button press to be more friendly with burst/ECS?

    [BurstCompile]
    public void OnUpdate(ref SystemState state)
    {
        if(query.IsEmptyIgnoreFilter)
            return;
       
        var job = new ProtoPopGrowthJob{};
        job.ScheduleParallel();
       
        state.EntityManager.RemoveComponent<ProtoPopCalTag>(query);
    }
}

2. I’d like to retrieve the total population from my entities and display it on TMP text in world space. I was setting up each entity to have its own canvas and text, but I noticed that the canvases can’t reference a camera outside of the sub-scene (as shown in the image below). Now I’m lost on trying to bridge the entity to UI gap. Any help would be appreciated.

9571039--1354360--Unity_056C5UYqTa.png
9571039--1354360--Unity_056C5UYqTa.png811×198 9.9 KB

2
  1. You need to show full code, as the error message does not seem to correlate to the code you have shown.
  2. You have to wire it up at runtime. I think most people just use Camera.main to get the camera. I use a cross-scene GUID solution for connecting subscene entities with scene GameObjects.
1 Like
3

Thank you.

Here is everything that touches the ProtoPopCalTag:

Population Growth ISystem:

using System.Collections;
using System.Collections.Generic;
using Unity.Burst;
using Unity.Entities;
using UnityEngine;
public partial struct ProtoPopGrowthSystem : ISystem
{
    private EntityQuery query;
  
    [BurstCompile]
    public void OnCreate(ref SystemState state)
    {
        query = state.GetEntityQuery(typeof(ProtoPopCalTag));
    }
  
    [BurstCompile]
    public void OnUpdate(ref SystemState state)
    {
        if(query.IsEmptyIgnoreFilter)
            return;
      
        var job = new ProtoPopGrowthJob{};
        job.ScheduleParallel();
      
        state.EntityManager.RemoveComponent<ProtoPopCalTag>(query);
    }
}

[BurstCompile]
public partial struct ProtoPopGrowthJob : IJobEntity
{
    //Run logic
    public void Execute(ProtoPopAspect protoPopData)
    {
        protoPopData.GrowPopulation();
    }
}

Population Calculate Button and Tag:

public class ProtoPopCalButton : MonoBehaviour
{
    private EntityManager entityManager;
    private EntityQuery query;

    void Start()
    {
        entityManager = World.DefaultGameObjectInjectionWorld.EntityManager;
        query = entityManager.CreateEntityQuery(typeof(ProtoPopCalTag));
    }

    public void OnButtonPress()
    {
        Entity entity = entityManager.CreateEntity();
        entityManager.AddComponentData(entity, new ProtoPopCalTag());
    }
}

public struct ProtoPopCalTag : IComponentData { }

I also just changed the ProtoPopCalTag from class to struct, but that didn’t fix anything.

4

Use QueryBuilder on line 13. The way you are doing it now is not Burst-compatible. Or just remove the [BurstCompile] on OnCreate if you don’t care that much on startup performance.

5

That solved it! Here’s the new version in case anyone else comes across a similar issue:

    private EntityQuery query;
  
    [BurstCompile]
    public void OnCreate(ref SystemState state)
    {
        query = SystemAPI.QueryBuilder().WithAll<ProtoPopCalTag>().Build();
    }

Also, I am looking at your framework for working with DOTS. Looks amazing. Is your GUID solution contained in that package? This solution sounds like it’ll help with more than just connecting UI.

6

Indeed it is. https://github.com/Dreaming381/Latios-Framework-Documentation/blob/main/Transforms/Getting%20Started.md#gameobjectentity

1 Like