Snapshot not sending child rotation for interpolated entity

[GameDeveloper1111]

Edit:

Resolved:

Solution:

overrides["Unity.Transforms.Rotation"].attribute.SendDataForChildEntity = true;

See source for more information:

@timjohansson

You have to use the same IGhostDefaultOverridesModifier as when adding new default overrides mentioned in https://docs.unity3d.com/Packages/com.unity.netcode@0.3/manual/ghost-snapshots.html (create a class implementing that interface in an assembly with a name ending with “.NetCodeGen”)

Instead of adding a new item you modify an existing one, so in the Modify method you would do something like

overrides["Unity.Transforms.Translation"].attribute.SendDataForChildEntity = true;
overrides["Unity.Transforms.Rotation"].attribute.SendDataForChildEntity = true;

Doing that will mean all translation and rotation components are ghosted for child entities in ghosts.

This is not the finalized API for it and I expect the way you do this to change in the future.

Edit: should also mention that the code is kind of pseudo-code, I did not compile and run it so you might need to change it slightly

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Original post:

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Goal:

I’m trying to present a ghost child entity (blue) of a client-interpolated ghost (red), but the server rotation data of the ghost child entity is not transferring to the client-side ghost child entity, despite the translation data of the ghost root entity transferring.

The ghost has no ghost owner and is in interpolation-only mode; i.e. there is no prediction or player input involved.

I’ve attached a minimal example .zip to this post. It’s based on https://github.com/Unity-Technologies/multiplayer/tree/master/sampleproject/Assets/Samples/NetCube

Here is a visualization of the goal:

Red: Ghost root entity
Blue: Ghost child entity

Here is the current state of things:

Here is the server update system:

using Unity.Entities;
using Unity.NetCode;
using Unity.Transforms;
using Unity.Mathematics;

[UpdateInWorld(UpdateInWorld.TargetWorld.Server)]
[UpdateInGroup(typeof(GhostSimulationSystemGroup))]
public class MoveCubeSystem : SystemBase
{
    protected override void OnCreate()
    {
    }

    protected override void OnUpdate()
    {
        float elapsedTime = (float)Time.ElapsedTime;

        Entities
            .ForEach((
                    Entity               entity,
                ref Translation          translation,
                ref MovableCubeComponent movableCubeComponent
                ) =>
        {
            // Translate cube (entity root) via time
            translation.Value.z += 0.05f * math.sin(elapsedTime * 2.5f);

            // Rotate child entity via time
            // NOTE: This data does not transfer to the client for some reason
            var childRotation = GetComponent<Rotation>(movableCubeComponent.ChildEntity);
            childRotation.Value = quaternion.Euler(0f, math.radians(movableCubeComponent.RotationSpeed * elapsedTime), 0f);
            SetComponent(movableCubeComponent.ChildEntity, childRotation);
        }).Run();
    }
}

To get the goal visualization video I ran this system on the client as well.

The Entities window in the Editor shows that the child’s rotation in the server world is updating while the child’s rotation in the client world is not, despite the translation of the root entity in each world updating. The child entity has a GhostChildEntityComponent.

7576516–938659–Interpolated-Child-Entity-Minimal-Example.zip (73.7 KB)

[GameDeveloper1111]

Below are screenshots showing that there exists a non-zero rotation on the server, but a zero rotation on the client, despite the translations matching (in LocalToWorld):

ServerWorld:

ClientWorld0:

Correlation: I did not have this child-entity-not-updating problem for interpolated ghosts when I had a corresponding ghost-owner-predicted ghost in another client world and ran updates for it in the server’s GhostPredictionSystemGroup.

[GameDeveloper1111]

@timjohansson

You have to use the same IGhostDefaultOverridesModifier as when adding new default overrides mentioned in https://docs.unity3d.com/Packages/com.unity.netcode@0.3/manual/ghost-snapshots.html (create a class implementing that interface in an assembly with a name ending with “.NetCodeGen”)

Instead of adding a new item you modify an existing one, so in the Modify method you would do something like

overrides["Unity.Transforms.Translation"].attribute.SendDataForChildEntity = true;
overrides["Unity.Transforms.Rotation"].attribute.SendDataForChildEntity = true;

Doing that will mean all translation and rotation components are ghosted for child entities in ghosts.

This is not the finalized API for it and I expect the way you do this to change in the future.

Edit: should also mention that the code is kind of pseudo-code, I did not compile and run it so you might need to change it slightly

This looks interesting. Will try.

Edit: It worked.

[ChrisPie]

Keep in mind IGhostDefaultOverridesModifier will be deprecated soon (or even removed in next version). So this is not a future-proof solution. What you should be doing is setting the flag in the component list of the prefab. If the checkboxes are greyed out, there’s a temporary fix somewhere on the forums. Even with that fix, you’ll need another fix from here:

IndexOutOfRangeException: Index 29 is out of range in DynamicBuffer of '29' Length.

Some update in regard that issue: First: to fix the SendForChildren option not correclty saved: change the the code in the GhostAuthoringComponent.cs with the following snippet: [SerializeField]private GameObject[] RefGameObjects; [SerializeField]private string[] ComponentNames; [SerializeField]private OverrideValue[] PrefabTypeOverrides; [SerializeField]private OverrideValue[] SendTypeOverrides; [SerializeField]private OverrideValue[] VariantOverrides; [SerializeField]private OverrideValue[…

to have the child override actually saved in the prefab. 0.6 buggy is enough that I regret using NetCode so soon.