Unreal Bridge

Blender 3.3 – 5.2 · Unreal Engine 5.2 – 5.8 · Windows

Mirror your Unreal project's real folder tree inside Blender, mark what is an asset, and push it into the open editor — with collision, sockets, LODs and naming already applied.

Prefer to watch? The whole pipeline is covered in a short video series — install and setup, folders, pushing, Live Sync, collision and LODs, skeletal meshes, and the rest: the full series on YouTube.

What this add-on does

Unreal Bridge is a one-way Blender → Unreal asset pipeline with a memory. You mark objects as asset roots, drop them into your Unreal project's own Content Browser folders — mirrored inside Blender — and press one button: the add-on exports FBX to a staging mirror and imports it into the running editor over Epic's own Python Remote Execution.

The memory is the part that matters day to day. Every pushed asset is recorded with a content hash, so:

• unchanged assets are skipped on the next push,
• the panel tells you which assets are new, edited, or already in Unreal,
• and Check Unreal can ask the live editor whether anything was moved or deleted behind your back.

It is the bridge only. It does not modify your Blender objects — every export happens on throwaway duplicates.

Your Unreal folders, mirrored in Blender

This is the part that changes how the day feels, so it is worth understanding first.

The panel shows your project's real Content Browser tree. Not a list you typed out and have to keep in sync — the actual folders, read from the .uproject on disk. /Game/Props/Electronics is there because it is there in Unreal.

Because it is read from disk rather than asked of the editor, it works with Unreal closed. You can link a project, browse its whole folder tree, and decide where every asset belongs without launching the engine at all.

Assign once and assets land in the right folder from the very first push. No import dialog. No dropping everything into /Game and dragging it into place afterwards. No renaming a folder in Unreal and then hunting for what you exported into the old one.

Every path is forced under /Game, so a typo can never target /Engine or another mount.

The picker is the project tree itself: indented, collapsible, with a search that reaches inside collapsed branches so you do not have to remember where something lives. Need a folder that does not exist yet? Type it as a new subfolder and Unreal creates it on the next import.

And because the mapping is remembered rather than retyped, reorganising in Blender reorganises Unreal. Move an asset into a different collection and the next push offers to move it in Unreal — keeping its references, its history and everything pointing at it — instead of importing a second copy somewhere else. Your Blender scene becomes the place you organise from, and the project follows.

Installing

1. Blender → Edit ▸ Preferences ▸ Add-ons ▸ Install from Disk.
2. Pick the tachyon_unreal_link zip.
3. Enable Unreal Bridge.
4. A welcome dialog appears once per install and points you at the three first steps.

The panel is in the 3D Viewport sidebar: press N, then the Unreal Bridge tab. You can rename that tab in the add-on preferences.

The Unreal Engine side

The add-on talks to a running editor. Three things have to be switched on in the project, once:

Then restart the editor once, and keep the project open while pushing.

Do It For Me

You do not have to do any of that by hand. As soon as a valid .uproject is linked, the panel audits those three settings by reading the project files, and offers a Do It For Me button if anything is missing. It edits .uproject and Config/DefaultEngine.ini, copying each original to *.tul-backup first and preserving the file's existing line endings so source control does not churn.

If the editor was open while it ran, the panel shows Restart Unreal to finish — the running editor still holds the old settings.

Firewall

On the first push, Windows asks whether to allow Blender through the firewall. Say yes. The traffic is UDP 6766 for discovery and TCP 6776 for commands, on localhost only. Nothing leaves your machine.

Linking your project

At the top of the panel, the PROJECT section:

The Unreal install itself is auto-detected: the .uproject's engine association first, then Epic launcher folders and a few common custom roots. If yours is somewhere unusual, set Unreal Engine Root in the add-on preferences — either the install folder or the path to UnrealEditor.exe.

Moving an asset to another folder

Reorganise in Blender — drag an asset into a different collection, or point its override somewhere new — and the next push notices that the asset is already in Unreal, just not where Blender now says it belongs. It asks before doing anything:

Until you answer, the asset does not pretend to be in sync. It reads Moved in Blender in the Folders list — amber, its own glyph — so a folder you reorganised does not quietly look finished.

It only asks when it is sure: the push record remembers which Blender object produced each asset, so "same object, different destination" is a fact rather than a guess. If the record cannot pin the asset down to exactly one previous path, nothing is moved and it imports normally — importing a duplicate is a nuisance, while moving the wrong asset in someone's project is not.

If you always want the same answer, Preferences ▸ Asset Moved to Another Folder makes it standing. It ships as Ask every time on purpose: both answers are reasonable, and which one is right depends on why the asset moved.

Live Sync never answers this for you. A folder change is a question, not an edit, so Live Sync leaves those assets alone and tells you to push by hand and choose.

Changing to a different project

Folder mappings are written in one project's vocabulary: /Game/Props means a folder that exists over there. Link a different .uproject and every mapping is a claim about a project that never made it — nothing errors, and the next push quietly builds a copy of the old project's folder tree inside the new one.

So the add-on notices, and asks:

Start fresh does not unmark anything. What is an Asset stays an Asset — that is a fact about your objects, not about the project they were last sent to. Only where things get sent is cleared, so you never have to re-mark a scene to change project.

A scene with no mappings is never interrupted, and re-picking the same project asks nothing. You can also clear the mappings deliberately at any time with Clear Folder Mappings in the ADVANCED section.

Your first push

1. Link the .uproject.
2. Select your object(s) and press Mark Selected as Asset. That object is now an asset root: it and all its children export as one FBX.
3. Add Unreal Folder, pick a folder from the project tree (or type a new subfolder name), then select the asset and press the folder row's assign button.
4. PUSH TO UNREAL.

With Unreal closed, Push still works — it writes the FBX and manifest to the staging mirror and tells you "Exported N to staging". The next push with the editor open imports them. Re-pushing is always safe.

The panel, section by section

Fresh out of the box the sections appear in this order. Every one of them can be reordered, or hidden from the sidebar, the pie menu and the quick window independently, in Preferences ▸ Layout.

PROJECT

The .uproject picker and the Unreal-setup audit described above. The header shows the linked project's name when collapsed, or not linked.

MARK AS ASSET

Nothing exports until it is marked. Three buttons apply to everything selected:

The Active dropdown below changes only the active object. The header summary shows the active object's state: Asset, Part of Parent or Never.

PUSH

With Live Sync on, two more toggles appear: Smart (send only what the edit touched) and Badge (the viewport readout).

The last line of the section is the report from the most recent push.

FOLDERS

The heart of the panel, in two collapsible parts.

SYNC STATUS is the key: one row per state, with its glyph, colour and how many assets are in it. Deleted in Unreal and Moved in Unreal stay hidden until a Check Unreal scan has actually produced one.

UNREAL FOLDERS is the list itself:

Both filters reset when you reopen the file, deliberately — a filter remembered into the next session would silently hide assets.

Each folder is one row. Registered folders are tinted green; folders that assets merely resolved into but which are not on your list are grey and marked as unlisted. On the row:

Expanding a folder lists its assets. The checkbox on each row is the viewport selection, in both directions: tick a row and the object is selected; select in the viewport and the row ticks. Drag down a column to range-select. Clicking the name jumps to the asset — deselect all, select the whole hierarchy, frame it — and shift-clicking adds to the selection without reframing. Each row can also show a LOD badge, a collision badge, and the status in words.

CHECK UNREAL

Asks the open editor where every mapped asset actually is. Covered in its own section below.

IMPORT SETTINGS

Which import preset this scene uses, and the full preset editor — the same editor as in Preferences, so the two can never drift apart. A scene stores only the preset's name, so presets follow you from project to project.

HIDDEN FOLDERS

Hides individual folders from this scene's folder list, by exact path. For blanket rules across all scenes — hiding everything containing Materials, say — use Preferences ▸ Folder picker.

ADVANCED

Sync status: the six words

Moved in Blender is worked out locally, from the push record alone — no scan needed. The last two come only from a Check Unreal scan, which is why the key hides all three until there is one to show.

The distinction matters: an asset you re-pointed is not a new asset. Reading it as Not in Unreal is what would have you push a second copy.

Check Unreal

Reconciliation asks the live editor about every mapped asset and reports one of four problems. Nothing is ever resolved automatically.

A moved asset is matched by its TulContentHash tag where possible, and each problem box says which evidence it rests on: Matched by content hash, or Matched by name only — check it is the same asset. Asset names are not unique in a real project, so a name-only match is shown for you to look at rather than acted on silently.

Results are grouped, not listed

Reorganise a project and a scan reports one row per asset — but a few hundred rows are rarely a few hundred decisions. They are usually one decision ("everything that was in /Game/Meshes is now in /Game/Props") repeated. So the panel folds the rows into groups: one per verdict, per folder that verdict is about.

Each group is a collapsible header — 200 assets moved to /Game/Props — carrying the buttons that settle it for the whole group at once: Follow all N in Blender and Move all N back in Unreal for moves, Link all N, Forget all N. When a group of moves mixes evidence it also offers Follow only the N confirmed, leaving the name-only matches for your eyes.

Moved assets group by where Unreal has them, not where Blender expected them — a single reorganisation drawn as one group rather than scattered across every folder it came from.

The buttons stay on the header whether the group is open or shut, so a group of two hundred can be settled without unrolling it. Groups of six or fewer open on their own; anything larger starts collapsed, listing twenty rows with a Show N more at the end. Every row keeps its own individual buttons — a bulk decision is offered, never forced.

Ambiguous results get no bulk button. Several assets share a name and none matched by hash, so choosing one for you would be a guess, not a shortcut.

Every bulk button asks first, in a dialog naming how many assets it covers, which folder, and what will actually happen — including that undoing a Move in Unreal does not reach the editor.

By default, opening a .blend runs a quiet scan in the background so the panel is honest the moment you look at it. It publishes verdicts only; it never adopts anything into the push record on its own, and it says nothing when the editor simply is not open. Turn it off with Check on file open in preferences.

Live Sync

Toggle Live Sync and edits send themselves. The add-on watches the depsgraph, waits for the quiet interval (1 second by default), and syncs everything that changed — but only in Object Mode, and only one round trip at a time. Anything you edit while one is in flight goes into the next.

It is smart about what it sends

The reason the second row works is that the add-on never imports materials: it runs the importer with Import Materials off and matches each slot against materials already in your project. So the only thing a full re-import would change after a material edit is which project material each slot points at — and that is one call per slot, straight to the open editor.

The safety rail is the slot layout. If the number of slots no longer matches, the sections themselves changed and only a real import can fix that, so the asset drops back to a normal push automatically. The same happens if the asset has never been pushed, if it is a skeletal mesh, or if the editor cannot be reached — nothing is ever quietly skipped.

Turn it off with Smart next to the Live Sync toggle (or Smart Live Sync in preferences) and every edit re-exports the whole asset.

Two details worth knowing. Material tracking only runs while Live Sync is on: with it off, a colour tweak deep in a shader graph that Unreal never imports would flag the asset as Needs update and only a pointless full push could clear it. And opening a .blend reports every material in it as changed, so there is a short quiet window after a file load before Live Sync starts listening.

The badge

While Live Sync is running, a small readout sits in the bottom-left corner of the 3D viewport:

The bottom line is there the whole time it is watching; the top line flashes for a few seconds after each sync and then fades. Turn it off with Badge next to the Live Sync toggle, or Viewport Status Badge in preferences.

The panel's report line says the same thing in words: Live: sending 3 to Unreal…, Live: imported 3, Live: materials on 1 asset (no FBX), Live: staged (3) — editor closed.

Import presets

A preset is a named set of Unreal FBX import options, stored in preferences rather than in the .blend, so one set of presets follows you across every project. A scene picks one by name.

One preset covers every engine version: the common settings first, then a section for settings added in later engines, which older engines simply ignore. The add-on deliberately forces Unreal's legacy FBX importer with an explicit FbxImportUI rather than Interchange, so one preset behaves identically on 5.2 and on 5.8.

Sections: Transform, Mesh, Normals & Tangents, Material, Skeletal Mesh, Animation, and Added in Unreal 5.3.

Defaults worth knowing:

• Combine Meshes on — an asset arrives as one static mesh.
• Auto Generate Collision off — your UCX_ / UBX_ / USP_ / UCP_ shapes stay authoritative.
• One Convex Hull per UCX on.
• Import Materials and Import Textures off, with material search set to All Assets — slot names match against materials already in the project instead of importing duplicates.
• Generate Lightmap UVs and Build Nanite off.
• LOD Group empty, which leaves Unreal's own default alone.

Nomenclature

Asset names are used as-is. An object called Crate_001 imports as Crate_001. Type prefixes (SM_, SKM_, SK_, Anim_) live in the preset's Nomenclature box and are off by default, because objects are usually already named to the convention and applying it regardless produced names like SM_SM_Crate. When enabled, a prefix is never applied twice.

Whatever the name, it is sanitised to [A-Za-z0-9_], given a leading underscore if it starts with a digit, and truncated to 96 characters.

Shortcuts and the quick window

Shift+E in Object Mode opens the pie menu (or the quick window — your choice in preferences). The binding is editable in Preferences ▸ Shortcuts, with a Restore button if it goes missing. It is bound to Object Mode only on purpose: Shift+E is Crease in Edit Mode.

The pie:

The quick window (also under Object ▸ Unreal Bridge) is the panel's fast twin: mark, push, and the whole Folders UI in a floating popup with no OK button — every row acts on its own.

One thing to know: the pie's Push to Unreal and the window's EXPORT TO UNREAL always push All Marked, even when the sidebar scope is set to Selected. Only the sidebar's own PUSH button follows the scope toggle.

Preferences

LODs and collision

Unreal Bridge reads what the companion Tachyon add-ons write, but does not need them installed.

Collision is matched by name, so it works no matter how you author it: any child mesh named UCX_, UBX_, USP_ or UCP_ rides inside the asset's FBX, and its materials are stripped at export. Auto Generate Collision stays off so your shapes are the ones Unreal uses.

Sockets are Empty children named SOCKET_. Static-mesh sockets get Unreal's +90° X convention applied automatically.

LODs export as one extra FBX per level and are applied to the imported asset, with each level's screen size pinned. A LOD that fails to import degrades to a warning — a base asset without its LODs still beats no asset — but a LOD that fails to export fails the whole asset, so you hear about it.

Both show as badges on the asset rows, and an edit to a LOD or a collision shape marks its asset as Needs update.

Export-only modifiers: any modifier whose name starts with ExportOnly_ and is turned off in the viewport is switched on for the export duplicates. It affects the FBX and nothing you see.

Bring your own LODs

You do not need Tachyon LOD Maker. A LOD level is just a mesh the add-on has been told is a level, so a chain you built yourself — decimated by hand, authored in another package, or shipped with a marketplace asset — works exactly the same: it exports as one FBX per level, gets its screen size pinned, and has its materials bound by name like any other.

Select the asset and open MARK AS ASSET:

Each level's screen size is editable on its row: the fraction of the view the asset fills when that level takes over. New levels start on a halving ladder — 0.5, 0.25, 0.125 — the same place LOD Maker starts.

Naming is matched against the asset's own name, so Crate_Lid_LOD1 is understood as a part of Crate rather than a level of it, and one asset's levels are never claimed by another.

The same is true of collision: UCX_, UBX_, USP_ and UCP_ are recognised by name whoever made them, so hand-modelled shapes need no companion add-on either.

Skeletal meshes and animation

Mark the armature, not the mesh

This is the one thing worth getting right, and it takes a second.

**Mark the armature as the Asset. Leave the skinned mesh as Part of Parent.**

A marked object becomes an export root, and the walk only ever descends into its children. Your mesh is a child of the armature, so marking the mesh leaves the armature — its parent — out of the export entirely: the FBX comes out with no bones and Unreal imports a static mesh. Marking both is worse, not safer: the mesh then exports twice, once correctly inside the armature's asset and again as a separate static mesh.

The rule generalises: mark the topmost object of the asset. For a prop that is the mesh; for anything skinned it is the armature.

If you do mark a skinned mesh, the MARK AS ASSET section says so and offers Mark the Armature Instead, which moves the mark up and sets the mesh back to Part of Parent in one click.

What you get in Unreal

One push of a marked armature produces:

Animation is pushed as its own Unreal asset rather than baked into the mesh, which is what Unreal expects. Each clip carries its own content hash, so an edited animation still goes when the mesh itself has not changed — and a mesh edit does not force every clip to re-import.

Which clips are exported

Preferences ▸ Animations:

An armature with no action assigned pushes the mesh and nothing else — that is not an error.

The root bone

Unreal expects a skeletal hierarchy to hang off a single bone at the origin called root. Rigs from Mixamo and most other libraries do not have one — their topmost bone is the hips — so Unreal promotes the hips to root, and anything that assumes a grounded root (root motion, retargeting, several IK setups) starts out wrong.

By default the add-on adds that bone to the exported FBX when it is missing, parenting the existing top-level bones under it. The bone is added to the export copy: your armature in Blender is never modified. The same bone is added to the mesh and to every animation, because a skeleton whose bone list does not match the one a clip was authored against is exactly what makes Unreal reject an animation import.

Validate Setup reports a rig that would reach Unreal with its hips acting as root — but only when nothing is set to fix it.

Rigs that arrive rotated

A rig imported from an FBX usually carries a rotation on the armature object — Mixamo's is +90° on X — because the rig is authored Y-up and Blender is Z-up. That rotation is applied to the bone data on the export copy, so the mesh and its animations are authored in one space and agree about which way is up. Without that step the character stands correctly in its reference pose and lies on its back the moment a clip plays. Your rig is not modified.

Companion add-ons

Two separate Tachyon add-ons share Unreal Bridge's sidebar tab and feed it directly. Both are optional, and both are sold separately — Unreal Bridge is complete without either.

The connection between them is deliberately loose. Each companion stamps plain ID properties on your objects, and Unreal Bridge reads those properties without importing the add-on. A missing companion never breaks a push, and a push never requires one.

What actually happens on a push

Where an asset lands — first the object's own override, then the innermost mapped collection walking outward, then the scene's default folder. Every path is forced under /Game; nothing can target /Engine or another mount.

The export works entirely on duplicates: the asset is isolated, duplicated, curves and metaballs converted, modifiers applied, sockets and collision fixed up, the root snapped to the origin, and the FBX written. It is all inside a safety net, so a failure never leaves stray copies or renamed originals behind. The FBX settings follow the conventions Unreal's importer expects and are locked by a node-level diff harness, so collision, sockets and slot-name material matching work with nothing to configure per import — and the bytes stay stable between releases, which is what keeps unchanged assets from re-importing.

Staging mirrors the destination: \\Game\Props\SM_Crate.fbx, with manifest.json at the project root and LODs beside their base as _LOD1, _LOD2.

Skipping is by content hash — one that ignores the FBX header, file ID and timestamp, so two exports of identical geometry hash the same. Unreal is the authority: each imported asset carries a TulContentHash tag, and the importer skips anything whose tag already matches. Force All overrides it.

The push record lives per Unreal project, not per .blend, under Blender's config folder — so two .blend files feeding the same project agree about what has been pushed.

Troubleshooting

Vertex colours

Vertex colours are exported by default, as Linear. The setting lives in the add-on preferences under Export.

Linear (the default) sends the values through unchanged, which is what you want when the colours are data — a mask, a blend weight, wind — and that is the usual reason to carry vertex colours into an engine. sRGB encodes them the way Blender's viewport shows them, which is what you want when the colours are paint. Do not export strips them from the FBX.

Both halves have to agree. The Unreal side is the import preset's Vertex Colour option, which defaults to Replace — "use the colours in the file". If colours are missing in Unreal, check that before anything else: an export set to Linear and an import set to Ignore will lose them just as thoroughly as the other way round.

Changing this re-exports every asset once. Unchanged assets are skipped by hashing the exported FBX, and this setting changes those bytes — so the first push after switching re-imports the library, exactly like the one-time cost of a Blender version change. The push after that skips as normal.

Blender 3.3's FBX exporter has no colour option at all, so the setting has no effect on 3.3. The preferences panel says so when you are running it.

Known limits

• Changing Blender version re-pushes everything once. Blender's own FBX exporter changes between releases, so the same asset exported from 4.3 and from 5.2 is not byte-identical. The add-on skips unchanged assets by hashing the FBX, so the first push after a Blender upgrade sees every asset as changed and re-imports it. It is one wasted round trip per asset, not a fault: the results are correct, and the push after that skips everything again.
• Sockets on skeletal assets are recorded in the manifest only — not yet applied to the UE Skeleton.
• The added root bone carries no motion. It is placed at the origin so Unreal has a proper root to retarget against, but the character's movement stays on the hips where the clip authored it. Root motion is not extracted, so enabling it in Unreal will not move the actor.
• Each action becomes one Anim Sequence. NLA strips are not evaluated, and an action is never split into several clips.
• Live Sync pushes only from Object Mode.
• Windows only.

Support

Watch the tutorial series — every section of this page, demonstrated.

Join us on Discord — questions, bug reports and feature requests. The same invite is in the add-on preferences, next to a link back to this documentation.

GPL-3.0-or-later. Copyright 2026 Tachyon Studio. Unreal Engine is required and not included; it is a free download from Epic Games. This add-on is the Blender-side bridge only and is not affiliated with or endorsed by Epic Games.