Mesh Gate

Live link from Cinema 4D and Blender into Unreal Engine, and back. User guide for Mesh Gate 1.0.0 and Mesh Gate Lite.

1. What it does

Mesh Gate keeps a Cinema 4D or Blender scene and an Unreal Engine level in step while you work. Move, model, deform or simulate in the DCC and the change appears in Unreal at once - no export, no import, no re-import. When the scene is right, Commit turns what is streaming into real Unreal assets and actors. The other way round, an actor in Unreal can be sent to the DCC, edited there, and baked back onto the same actor.

It has three parts: the Unreal plugin (the Mesh Gate Bridge), the Cinema 4D plugin, and the Blender add-on. You need the Unreal plugin and the part for your DCC.

2. What you need

macOS and Linux are not supported yet.

3. Install

Unreal Engine plugin

1. Install Mesh Gate from Fab into your engine (Fab Library, Install to Engine), or copy the C4DLiveLink plugin folder into your project's Plugins folder.
2. Open the project, enable Mesh Gate in Edit > Plugins if it is not enabled, and restart the editor.

Cinema 4D plugin

1. Download the Cinema 4D plugin from the Mesh Gate download page. Copy both folders in it - c4d_livelink and meshgate_fastpath (the C++ fast path; Mesh Gate works without it, more slowly) - into a Cinema 4D plugins folder, for example %APPDATA%\Maxon\Maxon Cinema 4D 2026_<id>\plugins, or a folder you add in Preferences > Plugins.
2. Restart Cinema 4D. The panel is under Extensions > Mesh Gate; the tag under Tags > Extensions > Mesh Gate.

Blender add-on

1. In Blender, Edit > Preferences > Get Extensions, the menu at the top right, Install from Disk, and pick the add-on .zip from the Blender folder of the Mesh Gate extras (Fab's additional files).
2. The panel is in the 3D viewport's sidebar (N), tab Mesh Gate.

4. Connect

1. Unreal: place a Mesh Gate Bridge actor in the level (Place Actors, search "Mesh Gate"). With Auto Connect on (the default) it connects to port 8412 by itself, and keeps retrying until something answers. The Mesh Gate bar appears in the level viewport.
2. Cinema 4D: open Extensions > Mesh Gate and press Start. Or Blender: press Start Live Link in the sidebar.
3. The Unreal log shows connected and hello from cinema4d (or blender). The scene arrives.

One DCC at a time per port: if Cinema 4D's link is running on 8412, Blender's cannot start on it. Change the port on both sides to run more.

5. Streaming

Every polygon object, generator and deformed object streams as a live preview, with its transform, UVs, normals, vertex colours and material slots. Cinema 4D Cloners (and Blender instancing) arrive as instances. Lights become Unreal lights; cameras become cine cameras. A spline with a cable radius set (meshgate.set_cable, see Scripting) is swept into a tube with UVs in centimetres.

Autosync and Sync

• Autosync on: changes stream as you make them.
• Autosync off: nothing is sent - and nothing is removed from Unreal - until you press Sync on an object's Mesh Gate tag (Cinema 4D) or Sync Selected (Blender). Use it on heavy scenes: commit in Unreal, pause, keep working, send only what is finished.

The Mesh Gate tag (Cinema 4D)

6. Materials

Name a folder of material instances in Unreal (Cinema 4D panel: Unreal materials folder; Blender sidebar: Unreal materials > Folder) and they appear as a dropdown on every object, per slot. Tick Build materials in Unreal in the DCC (the Cinema 4D panel, or Blender's Unreal materials box) and Mesh Gate builds material instances from the DCC's own materials and textures, into /Game/MeshGate.

7. Commit: real assets

Previews are temporary. Commit turns them into Static Mesh assets and actors that stay when the DCC is closed.

Identical meshes are folded into instanced actors (Instance Threshold, 4 by default). Assets go to Commit Folder (/Game/C4DCommitted) unless an object's tag names another. Meshes build in the background; the commit returns at once and the previews are replaced as each build finishes.

Proxies: an object that names a real Unreal asset (meshgate.set_proxy(obj, "/Game/Props/SM_Barrel", "both")) commits as that asset placed where the proxy stands - fitted by pivot, scale or both - instead of being baked itself. A Cloner of proxies commits as one instanced actor of the asset.

8. Unreal back to the DCC

Select an actor and press Send to DCC on the Mesh Gate bar. It arrives in Cinema 4D or Blender as an editable object standing in for the actor; the actor is hidden, not deleted. Edit it, then Bake Selected on the actor in Unreal writes the edit back onto the same actor and asset.

From a script, three modes (send_to_c4d, below): edit (the mesh, to model), transforms (the mesh as a proxy to simulate - only the actor's placement comes back), and instances (an ISM/HISM component as a Cloner, one clone per instance; the clones come back as instance transforms and custom data). Revert puts an actor back as it was before Mesh Gate first wrote into it.

9. Cameras

Streamed cameras are real cine cameras in Unreal - lens, filmback and focus follow the DCC. Bake Camera on the bar writes the selected camera's whole move into a Level Sequence (/Game/MeshGate/Cameras) that plays and renders with no DCC running.

10. Scripting

Every button has a script call that names what it acts on and returns what happened - for pipelines, and for AI assistants driving the applications through MCP.

Unreal Python

import unreal
lib = unreal.MeshGateScripting
lib.status()                                         # connected, application, document, ...
sent = lib.send_to_c4d([actor], "edit", 60.0)        # blocks until the DCC confirms
baked = lib.bake_back([actor])                       # the edit, onto the same actor
made = lib.commit([], "/Game/Tunnel")                # [] commits the whole session
lib.revert([actor])

Cinema 4D Python (Script Manager, or MCP's execute_python)

import meshgate
meshgate.status()
meshgate.sync([obj])                                 # ship now, whatever Autosync says
meshgate.commit([obj], "/Game/Tunnel")               # Unreal bakes them; returns what it made
meshgate.set_proxy(obj, "/Game/Props/SM_Barrel", "both")
meshgate.set_cable(spline, 2.0, sides=8)             # radius in cm

Blender Python

import meshgate
meshgate.sync([obj])
meshgate.commit([obj], "/Game/Tunnel")

Every call that sends, bakes or commits also takes job="..." (an id your pipeline uses to follow the work through every tool) and, where it bakes or commits, editor="..." (who edited: ai, person:<name>, or a process name). Both are optional.

11. Bridge settings (Unreal)

12. Logs and reports

Unreal: LogC4DLiveLink, LogC4DCommit, LogC4DPull and LogMeshGateScript in the editor log. While connected, a heartbeat every 10 s (heartbeat epoch 1, last ack 0.4s ago); if the DCC stops answering - frozen, or busy - no ack from Cinema 4D for 20s every 10 s until it is back.

Cinema 4D and Blender: their [MeshGate] console lines are also written to %LOCALAPPDATA%\MeshGate\logs, one file per day.

For pipeline monitoring, every side also writes JSON-lines reports (one transfer per line: started, done, error, with evidence) to C:\BABORepo\VLReports by default - change it in Project Settings > Plugins > Mesh Gate Reports, and for the DCCs with "vl_report_folder" in %LOCALAPPDATA%\MeshGate\settings.json.

13. Mesh Gate Lite

The free edition streams Cinema 4D and Blender into Unreal live - materials, lights, cameras and instances included - for up to 25 objects. Commit, sending from Unreal back to the DCC, Bake Camera and the Unreal script API are in the full version; Lite's buttons for them are greyed out. The Cinema 4D plugin and the Blender add-on are the same for both editions: upgrading means installing the full Unreal plugin in Lite's place.

14. Troubleshooting

15. Known limits

• Windows only. Unreal Engine 5.8.
• Cinema 4D sends nothing while you are still dragging; the move arrives when you release.
• Blender does not yet build instances sent from Unreal (it answers that it cannot); edit mode works.
• One DCC per port at a time.

Mesh Gate is an independent product, not affiliated with, endorsed or sponsored by Epic Games, Maxon or the Blender Foundation. Unreal Engine is a trademark of Epic Games, Inc.; Cinema 4D of Maxon Computer GmbH; Blender of the Blender Foundation.