Prometheus: Asset Streaming for Unity

Description

Prometheus is an open-source Unity package for efficient content streaming (loading and unloading assets). It’s optimized for performance, designed for content delivered with the game (no CDN support). Prometheus replaces Addressables, but it's not an in-place replacement as it has a different API in order to minimize overhead. Prometheus supports bursted loading/unloading requests. Loaded asset is a managed type so cannot be bursted (maybe there will be a hack with similar to UnityObjectRef entity).

Quick installation

Important: Follow the order below, as Prometheus depends on the com.kvd.utils package. Incorrect order may cause errors.

1. Add the com.kvd.utils package (a utility library used by Prometheus) to your Unity project via the Package Manager:
   • See Unity’s guide for Git packages.
   • URL: https://github.com/KamilVDono/com.kvd.utils.git
2. Add the Prometheus package the same way:
   • URL: https://github.com/KamilVDono/com.kvd.prometheus.git

For detailed installation options, see Setup Documentation.

Quick start

Get started with Prometheus in a few steps:

1. Install the package as described above.
2. Add a serialized field to your MonoBehaviour:

   public PrometheusReference assetReference;

   • Use [PrometheusReferenceType(typeof(TAssetType))] to constrain draggable asset types in the Inspector.
3. Start loading an asset:

   PrometheusLoader.Instance.StartAssetLoading(assetReference);

4. Retrieve the loaded asset:

   var result = PrometheusLoader.Instance.GetAsset<TAssetType>(assetReference);
   if (result.TryGetValue(out var asset))
   {
       // Asset is fully loaded and ready to use
   }
   else
   {
       // Asset is still loading or failed to load
   }

   • Option<TAssetType> returns:
     • None: Asset not available (still loading or failed).
     • Some: Asset fully loaded as TAssetType.
5. Unload the asset when done:

   PrometheusLoader.Instance.StartAssetUnloading(assetReference);

There are more queries, bursted API, callbacks API and more, see Usage documentation.

Example

using Prometheus;
using UnityEngine;

public class AssetLoaderExample : MonoBehaviour
{
    [PrometheusReferenceType(typeof(GameObject))]
    public PrometheusReference prefabReference;

    GameObject _instance;

    void Start()
    {
        PrometheusLoader.Instance.StartAssetLoading(prefabReference);
    }

    void Update()
    {
        if (_instance)
        {
            return;
        }
        
        var result = PrometheusLoader.Instance.GetAsset<GameObject>(assetReference);
        if (result.TryGetValue(out var prefab))
        {
            Debug.Log($"Prefab loaded: {prefab.name}");
            _instance = Instantiate(prefab);
        }
    }

    void OnDestroy()
    {
        if (_instance)
        {
            Destroy(_instance);
        }
        PrometheusLoader.Instance.StartAssetUnloading(prefabReference);
    }
}

Documentation

Explore detailed guides and API references:

• Documentation Overview
• Introduction
• Setup Guide
• Usage Guide

License

Prometheus is licensed under the MIT License. See LICENSE for details.

Future Plans

• Further allocations minimization
• Explore lightweight asset references (e.g., inspired by UnityObjectRef) for bursted contexts.
• Parallel burst API
• Optimized tooling for massive projects