Trouble with implementing unity.physics with ECS using DOTS stack | Official Unity Discord | Page 1

somber harbor May 1, 2023, 10:45 AM

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Hello I am having trouble implementing a working physics solution for my enemies, I want to add a physics rigid body and collider to them, unsure what I am doing wrong as I can't seen to get them to collide with each other and instead they just go right through each other. here is my code:

using UnityEngine;
using Unity.Entities;
using Unity.Mathematics;
using Unity.Transforms;
using Unity.Physics;
class EnemyAuthoring : MonoBehaviour
{
    public float3 TargetPosition;
    public float Speed;
}

 class EnemyBaker : Baker<EnemyAuthoring>
{
    public override void Bake(EnemyAuthoring authoring)
    {
        var entity = GetEntity(TransformUsageFlags.None);
        AddComponent(entity, new Enemy
        {
            CurrentPosition = float3.zero,
            TargetPosition = authoring.TargetPosition,
            Entity = entity,
            PhysicsVelocity = new PhysicsVelocity { Linear = float3.zero },
            PhysicsMass = PhysicsMass.CreateDynamic(MassProperties.UnitSphere, 1.0f),
            PhysicsCollider = new PhysicsCollider { Value = Unity.Physics.SphereCollider.Create(new SphereGeometry { Radius = 8.0f, Center = float3.zero }) }
        });

        AddComponent(entity, new LocalTransform
        {
            Position = float3.zero,
            Rotation = quaternion.identity,
            Scale = 1.0f
        });

    }
}

mellow vale May 1, 2023, 12:15 PM

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You need to add the physics components as components on the entity, not as members, see https://docs.unity3d.com/Packages/com.unity.physics@1.0/manual/create-body.html

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it's a lot easier if you have a MonoBehaviour prefab for your enemies and you add the Physics Shape and Physics Body authoring components there

somber harbor May 1, 2023, 12:29 PM

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mellow vale You need to add the physics components as components on the entity, not as membe...

thanks for the response, I have a prefab enemy but they are controlled by different ECS, there is no monoBehaviour besides this one on the enemy prefab, as I am trying to spawning many thousands, there is an ECS that spawns the enemies, one that moves them and this one which adds components, so I have to add a physics body and physics shape each as a seperate component the same way I added the LocalTransform component ?

mellow vale May 1, 2023, 1:03 PM

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what do you mean by "different ECS"?

somber harbor May 1, 2023, 1:07 PM

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well I have one component system that spawns the enemies and one that adds the components to them, which is this code, the code above is the script attached to each enemy, I had a look at that documentation but there didn't seem to be anything in it about how to create the physics bodies and shapes in the code they had as an example, I tried to do this but it also didn't work:

        AddComponent(entity, PhysicsMass.CreateDynamic(MassProperties.UnitSphere, 1.0f));
        AddComponent(entity, new PhysicsVelocity
        {
            Linear = float3.zero
        });

        AddComponent(entity, new PhysicsCollider
        {
            Value = Unity.Physics.SphereCollider.Create(new SphereGeometry { Radius = 8.0f, Center = float3.zero })
        });

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using Unity.Entities;
using Unity.Transforms;
using Unity.Burst;
using UnityEngine;


[BurstCompile]
public partial struct SpawnerSystem : ISystem
{
    public static int counter = 0;
    public void OnCreate(ref SystemState state) { }

    public void OnDestroy(ref SystemState state) { }

    [BurstCompile]
    public void OnUpdate(ref SystemState state)
    {
        foreach (RefRW<EnemySpawner> spawner in SystemAPI.Query<RefRW<EnemySpawner>>())
        {
            ProcessSpawner(ref state, spawner);
        }
    }
    private void ProcessSpawner(ref SystemState state, RefRW<EnemySpawner> spawner)
    {
        if (spawner.ValueRO.NextSpawnTime < SystemAPI.Time.ElapsedTime)
        {
            counter++;
            Entity newEntity = state.EntityManager.Instantiate(spawner.ValueRO.Prefab);
            state.EntityManager.SetComponentData(newEntity, LocalTransform.FromPosition(spawner.ValueRO.SpawnPosition));
            spawner.ValueRW.NextSpawnTime = (float)SystemAPI.Time.ElapsedTime + spawner.ValueRO.SpawnRate;

        }
    }
}

here is the enemySpawner system too

mellow vale May 1, 2023, 1:35 PM

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So you have a MonoBehaviour for the EnemySpawner, and that has a prefab that has the Enemy authoring component

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You can just add the physics components to your Enemy prefab, you don't need to add them in your EnemyBaker as that would be exactly the same result

somber harbor May 1, 2023, 1:40 PM

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yes to the first part that is how I have it set up, I had the components added to the enemy (normal rigid body and collidor) in the editor component part of the prefab but they did not collide at all

mellow vale May 1, 2023, 1:45 PM

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how are you moving the enemies?

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this example is probably relevant: https://docs.unity3d.com/Packages/com.unity.physics@1.0/manual/attract-body.html

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also you can turn on the physics debug rendering to make sure the colliders are working

somber harbor May 1, 2023, 1:48 PM

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using UnityEngine;
using Unity.Entities;
using Unity.Burst;
using Unity.Transforms;
using Unity.Mathematics;
using Unity.Physics;
[BurstCompile]
public partial struct EnemySystem : ISystem
{

    public void OnCreate(ref SystemState state)
    {

    }
    public void OnDestroy(ref SystemState state) { }
    [BurstCompile]
    public void OnUpdate(ref SystemState state)
    {
        var _player = GameObject.FindGameObjectWithTag("Player");
        float3 playerPosition = _player.transform.position;
        int enemyCount = 0;
        foreach (var (enemy, localTransform) in SystemAPI.Query<RefRW<Enemy>, LocalTransform>())
        {
            enemyCount++;
            MoveEnemy(ref state, enemy, playerPosition);
        }
    }
    private void MoveEnemy(ref SystemState state, RefRW<Enemy> enemy, float3 targetPosition)
    {
        Vector2 targetPosition2D = new Vector2(targetPosition.x, targetPosition.y);

        Entity enemyEntity = enemy.ValueRW.Entity;
        LocalTransform enemyTransform = state.EntityManager.GetComponentData<LocalTransform>(enemyEntity);


        Vector2 enemyPosition2D = new Vector2(enemyTransform.Position.x, enemyTransform.Position.y);

        Vector2 directionToPlayer = (targetPosition2D - enemyPosition2D).normalized;

 
        float speed = 0.01f;
        
        
        
        enemyTransform.Position.x += directionToPlayer.x * speed;
        enemyTransform.Position.y += directionToPlayer.y * speed;

        enemy.ValueRW.CurrentPosition = new float3(enemyTransform.Position.x, enemyTransform.Position.y, enemyTransform.Position.z);

        state.EntityManager.SetComponentData(enemyEntity, enemyTransform);
        state.EntityManager.SetComponentData(enemyEntity, enemy.ValueRW);
    }
}

oh sorry here is the enemySystem, that I use to move my enemies, it seems to work fine and how I want it too, I will have a look at that documentation too, how can I turn on the debug rendering?

mellow vale May 1, 2023, 1:51 PM

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you should have these components on a single game object in a subscene:

somber harbor May 1, 2023, 1:56 PM

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ok sweet, I think I figured out one part I was doing wrong also, I wasnt adding thephysics shape and physics body but adding a rigidbody2d and a boxcollider component to the prefab, I think this is now causing another problem with my code with adding the local transform component in my enemy authoring bake script

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yeah so I think I have collision going now, but I think I have broken the localTransform part of my enemySystem, I had to delete the addComponent in the enemy authoring that added a localTransform

mellow vale May 1, 2023, 2:41 PM

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oh yeah you don't need the LocalTransform, that gets added automatically based on the flags you pass to GetEntity in the baker

#Trouble with implementing unity.physics with ECS using DOTS stack