3D

Live link with Blender

Work on a 3D scene in Blender and see every change in JOS as you make it, and the other way round. Lights, cameras and transforms you set in JOS appear in Blender. Undo works in both applications.

What you need

• Blender 4.2 or later. Tested with 4.2 and 5.2.
• The JOS Live Link add-on. It is in the tools/blender/jos_live_link folder of your JOS installation.
• The same computer: JOS and Blender must run on one machine. The link only accepts connections from this computer.

Setting up

1. Install the add-on.
2. Zip the jos_live_link folder.
3. In Blender: Edit > Preferences > Add-ons > Install from Disk, pick the zip, and enable JOS Live Link.
4. Check JOS's side: in Edit > Preferences > Live link, Let 3D applications send their scenes (on this computer only) is on by default. The Port is 8790.
5. Check Blender's side: if you changed the port in JOS, set the same Port in the add-on's preferences.
6. Prepare JOS: add a ReadUSD for the scene and turn on its live link. - live stage chooses which Blender file it listens to. By default that is the .blend file's name; leave it empty to accept any. - The ReadUSD can point to an exported copy of the scene, or to no file at all, and receive everything over the link.
7. Connect: in Blender's 3D view, open the sidebar (N), go to the JOS tab and press Connect to JOS.

JOS's status bar shows the connection, for example "Live link: Blender: shot, updated 14:32:05". Hover over it for details.

What goes from Blender to JOS

• Objects:
• Meshes (with modifiers applied), curves, surfaces, metaballs and text, sent as meshes.
• Cameras, lights and empties, with their transforms and viewport visibility.
• Cameras: focal length, sensor, shift and clipping.
• Lights: point and spot become sphere lights, sun becomes distant, area becomes rect or disk. The brightness is approximate.
• Materials: the material's viewport colour.
• Deleted and renamed objects are removed in JOS.

Each change is one undo step in JOS, "Live link: Blender". Changes made within a second are merged into one step.

Animation

• Send animation (checkbox): while you scrub in Blender, the current frame's values are sent as they change.
• Bake to JOS: sends the whole frame range in one go, as one undo step, and turns on Send animation. Its options:
• Selected only
• Bake limit (MB): refuses bakes larger than this.

Blender's frame numbers line up with JOS's, shifted by the ReadUSD's time offset.

What goes from JOS to Blender

• Moves: moves you give the file's prims (in the 3D view or the Outliner) and the move of the group holding the ReadUSD move the Blender objects they apply to.
• Light3Ds and Camera3Ds: the lights in the ReadUSD's Scene, and the cameras of the RenderScenes rendering it, appear in Blender as objects named "JOS" plus the node's name (e.g. "JOS Light1") in a JOS collection. These are never sent back.

Undo, clearing and resending

• Undo: undo and redo in JOS also update Blender.
• Clear live edits (button on the ReadUSD): forgets everything received over the link. Ctrl+Z brings it back. Your files are never changed. Beside the button, JOS shows how much it has received ("live edits: 17.5 MB"); when that's a whole scene you didn't mean to send, clearing it makes the project small again.
• Resend all (Blender's JOS tab): sends the whole scene again, for example after Clear live edits.
• Errors: any errors are listed in the add-on's panel.

In the Outliner and on export

• Outliner: prims that exist only through the live link are shown in italics.
• WriteUSD: writes what the link sent into the exported file.

Not yet

• Materials beyond the viewport colour, UVs, normals and instancing.
• Blender's world as a dome light.
• Animated light and material values from Blender.
• Cards and primitives made in JOS aren't sent to Blender.
• Other applications: the link is for Blender only for now.