World Streaming for large worlds

Dawn Engine World Streaming automatically partitions very large worlds into grid cells, streams them in and out at runtime from player or camera streaming sources, and optionally provides HLOD distant proxies, Content Layers, content-bundle (DLC) mounting, and multiplayer synchronization.

Maturity: Delivered. Shipped as the WorldStreaming Gem. Runtime streaming is off by default and must be enabled explicitly in the project Settings Registry.

Double-precision large world coordinates address accuracy at large coordinates; World Streaming addresses load and memory scale. Open-world projects usually need both. See Double-precision rendering.

It does not replace PolyTerrain or Cesium 3D Tiles: those systems own mesh terrain topology and globe-scale geospatial LOD. World Streaming owns grid partitioning and distance-based residency for Prefab/Spawnable content, and can coexist via optional bridges.

What problem this solves

A map tens of kilometers across cannot stay fully resident in memory. Hand-splitting levels and placing load triggers is slow, error-prone, and painful for multi-user editing. World Streaming provides automatic grid partitioning and distance-based streaming so content enters and leaves memory without per-region load scripts.

It does not replace double-precision coordinates: a large world on absolute single-precision floats still jitters far from the origin.

How it works

Author (WorldConfig + partition view)
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.wsworld + shard Prefabs
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Asset Processor (PrefabProcessor + aggregator)
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 ├── .wsmanifest (+ optional .wschunk)
 └── Cell / HLOD Spawnables
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Runtime (WorldStreamingSystemComponent + streaming sources)
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On-demand Loaded / Activated world

1. Author: declare world configuration on the level (grids, content layers, HLOD) and place content in world space.
2. Bake: the editor assigns content to cells; Asset Processor produces cell Spawnables and a .wsmanifest.
3. Runtime: streaming sources resolve each cell’s desired state from Load / Activate radii; the system loads, activates, and unloads within budgets.
4. Optional: distant cells show HLOD proxies; Content Layers switch content sets; Content Bundles mount extra packs; multiplayer uses server-driven interest.

Startup uses a light Root Spawnable + Manifest + cell Spawnables model: the level root keeps resident config only; world content streams through the Manifest. Do not pack the same content into both Root and cells (use ws_blockOnRootDoubleInstance to catch double instantiation).

Two residency tiers run through the Gem:

• Loaded: entities are resident in memory but not simulating or rendering (warmup).
• Activated: entities are active for simulation and rendering.

Quick start (summary)

1. Enable the WorldStreaming Gem, then set /WorldStreaming/Enabled to true (and optionally DefaultManifest).
2. Create a level from the WorldStreaming_Level template (or migrate an existing level).
3. Place content, bake from Tools → World Streaming, add a Streaming Source to the player or camera.
4. Enter play mode and verify with ws_dumpStats / ws_drawRuntimeHash3D.

Sample automation levels live under AutomatedTesting/Levels/WorldStreaming/. For the full walkthrough and checklist, see Getting started.

Handbook chapters

Glossary

Limits and related capabilities

You can rely on:

• Grid partitioning, editor bake, runtime Loaded/Activated streaming with hysteresis and budgets;
• HLOD policies, Content Layers, Content Bundles (non-chunked root), multiplayer interest sync;
• Integration with double-precision large world coordinates (absolute-distance resolve; sources prefer *D translation).

Do not assume:

• Runtime enabled by default (you must set Enabled: true);
• Identical API or authoring workflow to other engines’ world-partition tools (Dawn uses Prefab/Spawnable shapes);
• Vegetation / navigation automatically taken over by bridges (defaults are often Coexist);
• HLOD meshes visible without AtomMode = Bridge;
• Content Bundles mountable on a chunked root, or mount state synced by handshake;
• That editor shards and server shards are the same concept.

Next steps

• Getting started: shortest path to a streaming level.
• Double-precision rendering: large-coordinate accuracy and render origin.
• PolyTerrain / Cesium 3D Tiles: mesh terrain and globe-scale geospatial streaming that can coexist with World Streaming.