Level Streaming Volumes

ALevelStreamingVolume controls sublevel load/unload. Legacy pattern compared to World Partition, but still used for tight per-region streaming control.

Setup

1. Level → Levels window → add sublevels as Always Loaded / Streaming
2. Place a LevelStreamingVolume over the area that should trigger streaming
3. In the Levels window, right-click each streaming sublevel → Stream In When Player Inside Volume → assign the volume

Properties

Property	Effect
Editor Pre-Vis Only	Volume affects editor view only, not runtime
Streaming Levels	Array of sublevels this volume controls
Use Blocking	Block the player's view until loaded
Disabled	Soft-disable the volume

Block-on-Load gotchas

If bShouldBlockOnLoad is true on the streaming level, the load happens synchronously — frame hitch on entry. Set false for async streaming with a fade-in.

When to use vs World Partition

Approach	When
Level Streaming Volumes	Legacy or specific transition-style maps; tight artist control over what loads when
World Partition	New projects, large open worlds; automatic per-cell streaming

You can use both in the same project — e.g. World Partition for the main world, traditional sublevels for instanced dungeons that LS volumes load.

Streaming API

Programmatic alternative — call from any actor:

ULevelStreaming* Lvl = UGameplayStatics::GetStreamingLevel(this, TEXT("MyDungeon_01"));
Lvl->SetShouldBeLoaded(true);
Lvl->SetShouldBeVisible(true);

Gotchas

• Volumes only trigger for the PlayerController's PlayerCameraManager, not arbitrary actors.
• Sublevels with persistent navigation must rebuild navmesh on load — expect a one-frame nav recalc.
• For multiplayer, the server decides streaming; client sublevels follow.