Nexus
Connect your interface to Blender
The page sends actions, Python executes the logic, and results and state return to the interface.
The path of an operation
- The user clicks a page button; the page gathers arguments.
- The page asynchronously calls a registered action.
- Python validates arguments and scene conditions, performs work, and returns serializable results.
- The page shows success or failure; affected state is invalidated.
- Subscribers receive authoritative snapshots and update lists or panels.
Choose actions, state, or events
| Need | Use | Why |
|---|---|---|
| Click to create or modify | Action | A request needs arguments, a result, and failure handling. |
| Show the current object or progress | State | Newly opened pages can read current facts too. |
| Notify that a task just finished | Event | Describes an occurrence, not persistent data. |
| Show an image or file | Resource references | Pass a reference, then read content as needed instead of sending local paths. |
Start read-only, then add changes
Start with Build your first add-on to read the scene. Confirm a trusted local window, registration after binding, and matching names on both sides. Then follow Call Python to add application arguments.
Once a call works, use State subscriptions to avoid repeated manual reads. For Blender-side changes, connect known data-change notifications to invalidate. The framework does not observe all application data automatically.
Distinguish business rejection from communication failure
No active object may be a normal application rejection. Missing registration, invalid connections, or unencodable arguments may reject an asynchronous call. Explain both cases instead of only disabling a button or always reporting success.
Return JSON-compatible strings, numbers, booleans, arrays, objects, or null, not Blender objects, path objects, or vectors. Handlers run on Blender's main thread; long loops block the UI. Page-side await does not move Python into the background.
Verify a real end-to-end path
- First opening reads the actual scene, not demo constants.
- After an action changes data, its result matches the actual object.
- Changes through Blender's own controls reach the page through state refresh.
- Repeated opening does not duplicate subscriptions or execution.
For events and disconnection, see Events and connection status.