GoInGameClientSystem.cs

using Unity.Burst;
using Unity.Collections;
using Unity.Entities;
using Unity.NetCode;

namespace KickBall
{
    public struct GoInGameRequest : IRpcCommand
    {
    }

    [WorldSystemFilter(WorldSystemFilterFlags.ClientSimulation | WorldSystemFilterFlags.ThinClientSimulation)]
    public partial struct GoInGameClientSystem : ISystem
    {
        [BurstCompile]
        public void OnCreate(ref SystemState state)
        {
            state.RequireForUpdate<EntityPrefabs>();
            state.RequireForUpdate<NetworkId>();
        }

        [BurstCompile]
        public void OnUpdate(ref SystemState state)
        {
            var ecb = new EntityCommandBuffer(Allocator.Temp);
            foreach (var (id, entity) in
                     SystemAPI.Query<RefRO<NetworkId>>()
                         .WithNone<NetworkStreamInGame>()
                         .WithEntityAccess())
            {
                ecb.AddComponent<NetworkStreamInGame>(entity);
                var req = ecb.CreateEntity();
                ecb.AddComponent<GoInGameRequest>(req);
                ecb.AddComponent(req, new SendRpcCommandRequest { TargetConnection = entity });
            }
            ecb.Playback(state.EntityManager);
        }
    }
}