Is it necessary to include GameObjects whose physics are deterministic in worldUpdate?

Question

In order to reduce data transfer size and the computational time for serializing world objects for each worldUpdate, I was wondering if it is possible to omit syncs for objects whose physics can be entirely, faithfully simulated on the client-side gameEngine (they are not playerObjects so playerInput does not affect them directly, and their physics are entirely deterministic). Interactions with these GameObjects would be entirely handled by GameEvents that are much less frequent. I feel like this should be possible if the client is running the same physics as the server and has access to the same initial conditions.

When I try to omit GameObjects from subsequent worldUpdates, I see that their motion becomes more choppy and they move faster than if they were not omitted; however, when I stop the game server while keeping the client open, their motion is more like what I would expect if I hadn't omitted them. This is all on my local machine with extrapolation synchronization.

OpherV · Answer 1 · 2017-06-06T07:14:28.330

The short answer is that the latest version of Lance (1.0.8 at the time of this writing) doesn't support user omission of game objects from world updates, but it does implement a diffing mechanism that omits objects from the update if their netScheme properties haven't changed, saving up on bandwidth.

This means that if you have static objects, like walls, for example, they will only get transmitted once for each player. Not transmitting this at all is an interesting feature to have.

If objects you're referring to are not static, then there is no real way to know their position deterministically. You might have considered using the world step count, but different clients process different world steps at different times due to the web's inherent latency. A client can't know what is the true step being handled by the server at a given point in time, so it cannot deterministically decide on such an object's position. This is why Lance uses the Authoritative server model - to allow one single source of truth, and make sure clients are synched up.

If you still want to manually avoid sending updates for an object, you can edit its netScheme so that it doesn't return anything but its id, for example:

static get netScheme() {
    return {       
        id: { type: Serializer.TYPES.INT32 }
    };
}

Though it's not a typical use due to the aforementioned reasons, so if you encounter specific sync issues and this is still a feature you're interested in, it's best if you submit a feature request in the Lance issue tracker. Make sure to include details on your use case to promote a healthy discussion

Is it necessary to include GameObjects whose physics are deterministic in worldUpdate?

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