TurretShootingSystem.cs

using Tutorials.Tanks.Step2;
using Unity.Burst;
using Unity.Entities;
using Unity.Mathematics;
using Unity.Rendering;
using Unity.Transforms;

namespace Tutorials.Tanks.Step4
{
    [UpdateInGroup(typeof(LateSimulationSystemGroup))]
    public partial struct TurretShootingSystem : ISystem
    {
        [BurstCompile]
        public void OnCreate(ref SystemState state)
        {
            state.RequireForUpdate<Execute.TurretShooting>();
        }

        [BurstCompile]
        public void OnUpdate(ref SystemState state)
        {
            foreach (var (turret, localToWorld) in
                     SystemAPI.Query<TurretAspect, RefRO<LocalToWorld>>()
                         .WithAll<Shooting>())
            {
                Entity instance = state.EntityManager.Instantiate(turret.CannonBallPrefab);

                state.EntityManager.SetComponentData(instance, new LocalTransform
                {
                    Position = SystemAPI.GetComponent<LocalToWorld>(turret.CannonBallSpawn).Position,
                    Rotation = quaternion.identity,
                    Scale = SystemAPI.GetComponent<LocalTransform>(turret.CannonBallPrefab).Scale
                });

                state.EntityManager.SetComponentData(instance, new CannonBall
                {
                    Velocity = localToWorld.ValueRO.Up * 20.0f
                });

                state.EntityManager.SetComponentData(instance, new URPMaterialPropertyBaseColor
                {
                    Value = turret.Color
                });
            }
        }
    }
}