World Streaming runtime streaming

Runtime streaming resolves a desired cell set from streaming sources each tick, then loads, activates, and unloads within concurrency and memory budgets.

Load and unload a world

Automatic path: set /WorldStreaming/DefaultManifest to a .wsmanifest path; the system component calls LoadWorld on activate.

Manual path:

auto* wp = WorldStreaming::WorldStreamingInterface::Get();
wp->LoadWorld(manifestAssetId);
wp->IsWorldLoaded();
wp->UnloadWorld();

Master switch /WorldStreaming/Enabled must be true. When false, engine behavior matches a project without streaming.

Content Bundles

Mount an extra .wsmanifest at runtime (DLC):

wp->MountContentBundle(bundleManifestAssetId);
wp->IsContentBundleMounted(bundleManifestAssetId);
wp->UnmountContentBundle(bundleManifestAssetId);

Constraints (v1):

• Same cellIdSalt and grids as the root world; no cell overlap; layers must match by id or introduce new ids.
• Not supported on a chunked root world.
• Mount state is not part of the multiplayer handshake; ServerDriven clients should mount the same bundles as the server.

Three forms of streaming source

Streaming Source component fields

Attach to player / camera; registers on activate and follows Transform (prefers HighPrecisionTransformBus double translation).

Coverage shapes

When m_shapes is non-empty: Sphere (default), Box, Capsule, Cone (extents.X horizontal half-angle radians, Y vertical half-angle, Z range), Polyline (m_pathPointsD, radius extents.X).

Resolve semantics

• Absolute world distance (double-precision friendly). Render-origin switches do not change desired cell state.
• Multiple Include sources merge; Exclude sources carve holes. Hard-reference bundles / DependentLoad may still pull cells to Loaded after an Exclude.
• Hysteresis defaults: UnloadHysteresisMeters 32, ActivateHysteresisMeters 16, UnloadCooldownSeconds 3.0.
• Global StreamingRangeScale scales radius-based sources; it does not scale explicit shapes or hysteresis.

Budgets and throttling

Server residency modes (Runtime/ServerStreamingMode): StreamInOut (default) / StreamInOnly / FullyResident. See Multiplayer.

Progress, blocking, and pause

BlockOnSlowStreaming (default off) can auto-block when lag exceeds thresholds; AutoBlockCooldownSeconds default 5.0. World reload resets streaming enabled to on. ws_dumpStats reports streaming=PAUSED when frozen.

Notifications (C++)

WorldStreamingNotificationBus includes: OnCellStateChanged, OnCellStateTransitionDetail, OnWorldLoaded / OnWorldUnloaded, OnLayerRuntimeStateChanged, OnCellLoadFailed, OnContentLayerLoaded, OnStreamingPerformanceChanged, OnContentBundleMounted / OnContentBundleUnmounted, OnHlodFragmentVisibilityChanged.

Script-facing notifications: Scripting.

Next steps

• Content Layers / HLOD: gate and proxy content.
• Scripting: register transient sources and query progress.
• Configuration and debugging: full Runtime key and CVar tables.