Change Detection

Overview

When using Networked Properties a common use case is to have code executed whenever the value of a Networked Property changes.

OnChangedRender

The OnChangedRender attribute is the easiest way for handling Render based Change Detection.

To detect changes on a Networked Property, add a OnChangedRender attribute to it. The attribute takes a method name. The given method needs to be a void function on the same NetworkBehaviour.

IMPORTANT: OnChangedRender is not called when the object is first spawned on a client. To initialize an object use the override Spawned function and call your changed function from there or initialize the object manually.

Example:

C#

public class Example : NetworkBehaviour
{
    [Networked, OnChangedRender(nameof(OnColorChanged))]
    public Color NetworkedColor  { get; set; }
    
    public Material material;

    public void OnColorChanged()
    {
        material.color = NetworkedColor;
    }
}

Previous Value

Access to the previous value before the change occurred is possible.

C#

[Networked]
[OnChangedRender(nameof(CounterChanged))]
public int Counter { get; set; }

void CounterChanged(NetworkBehaviourBuffer previous)
{
    var prevValue = GetPropertyReader<int>(nameof(Counter)).Read(previous);
    Log.Info($"counter changed: {Counter}, prev: {prevValue}");
}

The type when calling GetPropertyReader<T> needs to match the type of the Networked Property.