Overview

Model in Blender, see it in Unity or Unreal instantly. Loom streams your meshes, rigs, lights, cameras and materials straight into the engine viewport over a direct binary link. Edit a vertex, scrub an animation, tweak a light, and it shows up in milliseconds. No exporting, no FBX round-trips, no relay server. Block a level out and replace the stand-ins with your real prefabs or Blueprints from either application. When you are happy, bake the whole session to real prefabs, Blueprints and assets. Loom is a preview and a pipeline.

Release candidate. Loom is at 0.10.0, the release candidate for 1.0 (wire protocol v40). Every feature described here is implemented and continuously tested across both engines. What remains before 1.0 is a hands-on pass over how the interface feels and the first run, and the store listings. See Status & Roadmap.

One producer, two engines

Loom is a Blender producer with two first-class consumers. The same wire drives both, so every capability lands in whichever editor you open.

• Unity (C# / URP) is the reference consumer.
• Unreal (C++ / UE Material) is a peer on the same wire, built as a UE 5.6 editor plugin. It re-bases the wire into Unreal space (Z-up, centimetres) on receipt and maps each Unity concept to its idiomatic Unreal target.

What syncs

• 9 Blender object types: mesh, curve, text, surface, metaball, armature, light, camera, empty.
• All 1 to 8 UV channels plus RGBA vertex colours, with 32-bit indices for big meshes.
• Armatures and shape keys, with live pose and blendshape weights.
• 4 light types, perspective and orthographic cameras with depth of field, world HDRI and fog.
• Collection, geometry-node and particle instancing, with linked-duplicate dedup.
• Prefab-reference placement: a loom_prefab key on an object or on its mesh data spawns your real prefab or Blueprint from a registry in either engine.
• Greybox → final replacement, driven from Blender or from either editor.
• A Tracked Objects list that says exactly what is streaming, with Exclude and Include.
• Boolean cutters and SNAP_ / SOCKET_ marker empties skipped automatically.
• Principled materials with content-deduped textures.
• 20+ shader nodes transpiled to real URP shaders, all 19 Mix blend modes.
• Live colliders, LOD groups, and game-ready layer, tag and static routing, with generators in Blender that make the proxies and LOD chains for you.
• Attach points: sockets and plugs with a shared tag, snapped in Blender and carried to both engines.
• Rigid bodies: Blender’s Rigid Body settings become a real physics body in either engine, sent as Blender’s own physics engine simulates them and measured against it.
• A tile test that places copies of a kit piece around it, to check its seams under the engine’s lighting. Both bakes leave the copies out.

Greybox to final

The live scene is a blockout; your finished props live in the project. Give a blockout a prefab key, from Set Prefab Key… in Blender’s N-panel or from REPLACE GREYBOX in either editor window, and it spawns your real prefab or Blueprint at the Blender transform instead of streaming geometry. Key the mesh data and every linked duplicate follows; pick a pool variant by name; Scatter pool… deals a pool over every placement from a seed. Every assignment is written into the .blend and Ctrl+Z there undoes it, so a half-replaced level survives a restart of both applications. Mark stand-ins as blockouts and all three applications show the same 62 of 210 progress, with a PREFAB CHECK list that flags an unmapped key or an out-of-pool variant rather than substituting something plausible in silence.

A four-page “How replacement works” explainer ships in all three applications, word for word, behind a ? wherever the question comes up. It documents, it never acts.

Preview to production

The live preview is not a dead end. Bake a session into real project assets: a Unity .prefab or an Unreal BP_LoomBake Blueprint over saved meshes, materials and textures, with lightmap UVs, LOD groups and colliders generated at bake. Bake everything, or select synced objects and press Bake Selected… for just those subtrees. You can also bake a frame range to an AnimationClip or UAnimSequence, record and replay a session to a .loomcache file, or bake a .blend with no editor open from one command, blender -c loom_bake, for CI.

Where to next

• New to Loom? Read the Unity Quick Start or Unreal Quick Start.
• Working in Blender? The Blender Producer Guide covers the N-panel, scope, blockouts, scatter and the tracked list.
• Curious how it works? See Architecture and Why It’s Fast.

Compatibility

License

The Loom Blender add-on is free and MIT-licensed. The Unity and Unreal consumer plugins are commercial and will be sold under the Unity Asset Store and Fab licenses.