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Using The Exporter

UntoldEngine ships two user-facing exporter commands in the scripts/ folder at the repo root:

  • export-untold
  • export-untold-tiles

These wrappers launch Blender in background mode and run the Python exporters for you. Users should run the shell wrappers, not the raw Blender commands.

Prerequisites

Blender must be installed.

The wrappers resolve Blender in this order:

  1. --blender /path/to/Blender
  2. BLENDER_BIN=/path/to/Blender
  3. /Applications/Blender.app/Contents/MacOS/Blender
  4. blender on PATH

If Blender cannot be found, the wrapper prints an install message and exits.

Export A Single Asset

Use export-untold (found in scripts/) to convert one USD or USDZ asset into one .untold runtime file.

Basic usage:

./scripts/export-untold \
  --input /path/model.usdz \
  --output /path/model.untold

Common options:

  • --input <path>: required source .usd, .usda, .usdc, or .usdz
  • --output <path>: required destination .untold
  • --file-type <tile|lod|hlod|shared>: optional, defaults to tile
  • --mesh-name <name>: optional, export only one mesh from a multi-mesh asset
  • --ConvertOrientation: optional, convert the export into engine space
  • --source-orientation <blender-native|engine-oriented>: optional, defaults to blender-native
  • --validate: optional, also writes <name>.validation.json
  • --blender <path>: optional wrapper-level Blender override

Example:

./scripts/export-untold \
  --input GameData/Models/robot/robot.usdz \
  --output GameData/Models/robot/robot.untold \
  --ConvertOrientation \
  --source-orientation blender-native \
  --validate

Expected output:

  • robot.untold
  • Textures/... beside the .untold file if the asset uses textures
  • robot.validation.json only when --validate is passed

Export A Scene Into Tiles

Use export-untold-tiles (found in scripts/) to partition a USD or USDZ scene into tile payloads and generate a manifest JSON file.

Basic usage:

./scripts/export-untold-tiles \
  --input /path/scene.usdz \
  --output-dir /path/tile_exports \
  --tile-size-x 25 \
  --tile-size-y 10000 \
  --tile-size-z 25

Common options:

  • --input <path>: required source .usd, .usda, .usdc, or .usdz
  • --output-dir <path>: required destination directory for tile payloads
  • --tile-size-x <number>: optional tile width in world units
  • --tile-size-y <number>: optional tile height in world units, defaults to 10000
  • --tile-size-z <number>: optional tile depth in world units
  • --auto-tile-size: optional automatic tile sizing
  • --generate-hlod: optional HLOD generation
  • --generate-lod: optional per-tile LOD generation
  • --dry-run: optional planning pass without writing payload files
  • --write-manifest-in-dry-run: optional manifest write during dry run
  • --visible-only: optional export only visible meshes
  • --all-meshes: optional include hidden meshes
  • --debug-aabb-only: optional emit debug AABB payloads instead of geometry
  • --quadtree: optional partition tiles using a quad-tree instead of a uniform grid
  • --scene-profile <auto|indoor|outdoor>: optional streaming radius profile, defaults to auto. Radii are always proportional to scene size — no fixed distances to hand-tune. Use outdoor for cities, terrain, and large exterior scenes if auto-detection misses.
  • --floor-count <number>: optional number of vertical floors to split each tile into
  • --blender <path>: optional wrapper-level Blender override

Example:

./scripts/export-untold-tiles \
  --input GameData/Models/dungeon/dungeon.usdz \
  --output-dir GameData/Models/dungeon/tile_exports \
  --tile-size-x 25 \
  --tile-size-y 10000 \
  --tile-size-z 25 \
  --generate-hlod \
  --generate-lod

Dry-run example:

./scripts/export-untold-tiles \
  --input GameData/Models/dungeon/dungeon.usdz \
  --output-dir GameData/Models/dungeon/tile_exports \
  --tile-size-x 25 \
  --tile-size-y 10000 \
  --tile-size-z 25 \
  --dry-run \
  --write-manifest-in-dry-run

Expected output layout:

  • dungeon.json beside the tile payload directory
  • tile_exports/tile_*.untold
  • optional HLOD and LOD .untold files in tile_exports/
  • tile_exports/Textures/... for staged textures

The manifest stores relative runtime paths so it remains portable across machines, repos, and app bundles.

Selective Merging With The NM_ Prefix

When MERGE_BY_MATERIAL is enabled (the default), objects that share the same material within a tile are joined into a single mesh entity before export. This reduces draw calls significantly, but means multiple original objects collapse into one exported entity — losing their individual names.

If you need certain objects to remain as separate identifiable entities (for example, to support tap-to-select workflows or per-object JSON lookups at runtime), prefix their name in Blender with NM_.

Objects whose name starts with NM_ are excluded from the merge step and exported individually, preserving their original name in the .untold file. All other objects are still merged normally.

Example naming in Blender:

  • NM_Pipe_001 — exported as its own entity, name survives into .untold
  • NM_LightFixture_A — exported as its own entity
  • Wall_North — merged with other same-material walls, one entity for the group
  • Door_Main — merged with same-material doors

This lets you keep background geometry (walls, floors, ceilings) optimized while still being able to identify and interact with specific objects at runtime:

To change the prefix or disable selective merging, edit NO_MERGE_PREFIX at the top of scripts/tilestreamingpartition.py. Set it to "" to merge all objects regardless of name.

Optimization Workflows

After exporting assets, use Optimizations for optional workflows such as ASTC texture compression and LZ4 geometry compression.

Loading The Result In The Engine

Single asset:

setEntityMeshAsync(
    entityId: entityId,
    filename: "robot",
    withExtension: "untold"
)

Tiled scene:

let sceneRoot = createEntity()
setEntityName(entityId: sceneRoot, name: "dungeon")
setEntityStreamScene(entityId: sceneRoot, manifest: "dungeon", withExtension: "json")

The manifest should live next to the tile payload directory. Tile, HLOD, LOD, and shared-bucket payloads are resolved relative to the manifest file.

Notes

  • .untold tile payloads participate in the current tiled streaming architecture, including tile-level load/unload, remote download + cache, per-tile LOD/HLOD, and large-tile OCC sub-mesh streaming when the runtime classifies a tile into the OOC path.
  • The Python files in scripts/ are implementation details. The recommended user entry points are the shell wrappers in the same folder.