2D Interaction Zones

A WebPhysicsZone2D marks a conveyor section where bottles or containers interact in dense flow. Inside its box volume, Box2D simulates their movement and contact from the top down: parts can gather, push against one another and move around guides, but they do not fall or tip. Parts entering the zone switch to 2D physics and return to conveyor transport at the discharge surface.

Status: internal / commercial feature (beta). 2D interaction zones are not part of the Community edition.

Zone kinds

Jam

Use Jam for accumulation on a conveyor, such as bottles queuing behind a blocked outlet. Resting bottles can go to sleep to reduce simulation work, then move again as space opens ahead of them.

BufferTable

Use BufferTable for bottles or containers collecting across a broad table before feeding into an outfeed conveyor. Parts move freely across the surface and interact with their neighbours; Damping controls how quickly their motion slows down.

Diverter

Use Diverter where a moving switch directs bottles or containers towards different conveyor outlets. Assign its drives in KinematicDrives so the moving switch bodies follow the drive motion; routing decisions remain in your control logic.

Merge

Use Merge where incoming flows join a common discharge conveyor and parts compete for space. Assign any moving merge elements through KinematicDrives, and use your control logic to coordinate gaps and release order.

Add a zone in the editor

1. Open the Asset Editor, select the node for the conveyor section and add Physics Zone 2D. The editor adds a Box Collider on that node if one is missing; each node supports one 2D interaction zone.
2. Use the box handles to position and resize the zone over the conveyor section where parts should interact. The Box Collider defines the zone volume.
3. Assign Surface to the destination or discharge transport surface that receives parts leaving the zone. For a diverter or merge with moving elements, assign their drive references in KinematicDrives.
4. Select Kind: Jam, BufferTable, Diverter or Merge. New zones default to Jam.
5. Leave ShowGizmo enabled to see the zone as a wireframe box while checking its placement. Turn it off when you no longer need the outline.

For example, cover a buffer table and its interaction area with the box, select BufferTable, and set Surface to its outfeed conveyor. Run the flow and check that containers collect on the table and return to conveyor transport at the outlet.

TODO-SCREENSHOT: buffer table and diverter in the viewer

Limits and engine build

Plan for about 10,000 bottles in total, with at most 7,000 awake at once. Awake bottles are those still actively simulated; settled bottles can sleep. These are the beta operating targets, with final performance measurements still pending.

The compat engine build is the default. The faster SIMD/threaded deluxe build is available only when the hosting page is cross-origin isolated; pages without that isolation use compat.

See also

• Physics — Moving Parts and Payload — 3D physics for falling, sliding, tipping and stacking parts, and loads on moving machine parts.