Class PredictedSimulationSystemGroup
The parent group for all (roughly) deterministic gameplay systems that modify predicted ghosts. This system group runs for both the client and server worlds at a fixed time step, as specified by the SimulationTickRate setting. To understand the differences between this group and the PredictedFixedStepSimulationSystemGroup, refer to the PredictedFixedStepSimulationSystemGroup documentation.
On the server, this group is only updated once per tick, because it runs in tandem with the Unity.Entities.SimulationSystemGroup. In other words, because the SimulationSystemGroup runs at a fixed time step, and only once per frame, this system inherits those properties. On the client, the group implements client-side prediction logic by running the client simulation ahead of the server.
Important: Because the client is predicting ahead of the server, all systems in this group are updated multiple times per simulation frame, every time the client receives a new snapshot (see NetworkTickRate and SimulationTickRate). This is called rollback and re-simulation.
These re-simulation prediction group ticks also get more frequent at higher pings. For example, a client with a 200ms ping is likely to re-simulate roughly twice as many frames than a client with a 100ms connection, with caveats. The number of predicted, re-simulated frames can easily reach double digits, so systems in this group must be exceptionally fast, and are likely to use a lot of CPU. You can use prediction group batching to help mitigate this. Refer to MaxPredictionStepBatchSizeRepeatedTick.
This group contains all predicted simulation (simulation that is the same on both client and server). On the server, all prediction logic is treated as the authoritative game state, which is only simulated once.
Note: This SystemGroup is intentionally added to non-netcode worlds, to help enable single-player testing.
Inheritance
Inherited Members
Namespace: Unity.NetCode
Assembly: Unity.NetCode.dll
Syntax
[WorldSystemFilter(WorldSystemFilterFlags.Default|WorldSystemFilterFlags.ThinClientSimulation, WorldSystemFilterFlags.Default)]
[UpdateInGroup(typeof(SimulationSystemGroup), OrderFirst = true)]
[UpdateBefore(typeof(FixedStepSimulationSystemGroup))]
[UpdateAfter(typeof(BeginSimulationEntityCommandBufferSystem))]
public class PredictedSimulationSystemGroup : ComponentSystemGroupRemarks
Because child systems in this group are updated so frequently (multiple times per frame on the client, and for all predicted ghosts on the server), this group is usually the most expensive on both builds. Pay particular attention to the systems that run in this group to keep your performance in check.