---
name: tabletopkit
description: "Create multiplayer spatial board games using TabletopKit on visionOS. Use when building tabletop game experiences with boards, pieces, cards, and dice, managing player seats and turns, synchronizing game state over FaceTime with Group Activities, rendering game elements with RealityKit, or implementing piece snapping and physics on a virtual table surface."
---

# TabletopKit

Create multiplayer spatial board games on a virtual table surface using
TabletopKit. Handles game layout, equipment interaction, player seating, turn
management, state synchronization, and RealityKit rendering. **visionOS 2.0+
only.** Targets Swift 6.3.

## Contents

- [Setup](#setup)
- [Game Configuration](#game-configuration)
- [Table and Board](#table-and-board)
- [Equipment (Pieces, Cards, Dice)](#equipment-pieces-cards-dice)
- [Player Seats](#player-seats)
- [Game Actions and Turns](#game-actions-and-turns)
- [Interactions](#interactions)
- [RealityKit Rendering](#realitykit-rendering)
- [Group Activities Integration](#group-activities-integration)
- [Common Mistakes](#common-mistakes)
- [Review Checklist](#review-checklist)
- [References](#references)

## Setup

### Platform Requirement

TabletopKit is exclusive to visionOS. It requires visionOS 2.0+. Multiplayer
features using Group Activities require visionOS 2.0+ devices on a FaceTime
call. The Simulator supports single-player layout testing but not multiplayer.

### Project Configuration

1. `import TabletopKit` in source files that define game logic.
2. `import RealityKit` for entity-based rendering.
3. For multiplayer, add the **Group Activities** capability in Signing &
   Capabilities.
4. Provide 3D assets (USDZ) in a RealityKit content bundle for tables, pieces,
   cards, and dice.

### Key Types Overview

| Type | Role |
|---|---|
| `TabletopGame` | Central game manager; owns setup, actions, observers, rendering |
| `TableSetup` | Configuration object passed to `TabletopGame` init |
| `Tabletop` / `EntityTabletop` | Protocol for the table surface |
| `Equipment` / `EntityEquipment` | Protocol for interactive game pieces |
| `TableSeat` / `EntityTableSeat` | Protocol for player seat positions |
| `TabletopAction` | Commands that modify game state |
| `TabletopInteraction` | Gesture-driven player interactions with equipment |
| `TabletopGame.Observer` | Callback protocol for reacting to confirmed actions |
| `TabletopGame.RenderDelegate` | Callback protocol for visual updates |
| `EntityRenderDelegate` | RealityKit-specific render delegate |

## Game Configuration

Build a game in three steps: define the table, configure the setup, create the
`TabletopGame` instance.

```swift
import TabletopKit
import RealityKit

let table = GameTable()
var setup = TableSetup(tabletop: table)
setup.add(seat: PlayerSeat(index: 0, pose: seatPose0))
setup.add(seat: PlayerSeat(index: 1, pose: seatPose1))
setup.add(equipment: GamePawn(id: .init(1)))
setup.add(equipment: GameDie(id: .init(2)))
setup.register(action: MyCustomAction.self)

let game = TabletopGame(tableSetup: setup)
game.claimAnySeat()
```

Call `update(deltaTime:)` each frame if automatic updates are not enabled via
the `.tabletopGame(_:parent:automaticUpdate:)` modifier. Read state safely with
`withCurrentSnapshot(_:)`.

## Table and Board

### Tabletop Protocol

Conform to `EntityTabletop` to define the playing surface. Provide a `shape`
(round or rectangular) and a RealityKit `Entity` for visual representation.

```swift
struct GameTable: EntityTabletop {
    var shape: TabletopShape
    var entity: Entity
    var id: EquipmentIdentifier

    init() {
        entity = try! Entity.load(named: "table/game_table", in: contentBundle)
        shape = .round(entity: entity)
        id = .init(0)
    }
}
```

### Table Shapes

Use factory methods on `TabletopShape`:

```swift
// Round table from dimensions
let round = TabletopShape.round(
    center: .init(x: 0, y: 0, z: 0),
    radius: 0.5,
    thickness: 0.05,
    in: .meters
)

// Rectangular table from entity
let rect = TabletopShape.rectangular(entity: tableEntity)
```

## Equipment (Pieces, Cards, Dice)

### Equipment Protocol

All interactive game objects conform to `Equipment` (or `EntityEquipment` for
RealityKit-rendered pieces). Each piece has an `id` (`EquipmentIdentifier`) and
an `initialState` property.

Choose the state type based on the equipment:

| State Type | Use Case |
|---|---|
| `BaseEquipmentState` | Generic pieces, pawns, tokens |
| `CardState` | Playing cards (tracks `faceUp` / face-down) |
| `DieState` | Dice with an integer `value` |
| `RawValueState` | Custom data encoded as `UInt64` |

### Defining Equipment

```swift
// Pawn -- uses BaseEquipmentState
struct GamePawn: EntityEquipment {
    var id: EquipmentIdentifier
    var initialState: BaseEquipmentState
    var entity: Entity

    init(id: EquipmentIdentifier) {
        self.id = id
        self.entity = try! Entity.load(named: "pieces/pawn", in: contentBundle)
        self.initialState = BaseEquipmentState(
            parentID: .init(0), seatControl: .any,
            pose: .identity, entity: entity
        )
    }
}

// Card -- uses CardState (tracks faceUp)
struct PlayingCard: EntityEquipment {
    var id: EquipmentIdentifier
    var initialState: CardState
    var entity: Entity

    init(id: EquipmentIdentifier) {
        self.id = id
        self.entity = try! Entity.load(named: "cards/card", in: contentBundle)
        self.initialState = .faceDown(
            parentID: .init(0), seatControl: .any,
            pose: .identity, entity: entity
        )
    }
}

// Die -- uses DieState (tracks integer value)
struct GameDie: EntityEquipment {
    var id: EquipmentIdentifier
    var initialState: DieState
    var entity: Entity

    init(id: EquipmentIdentifier) {
        self.id = id
        self.entity = try! Entity.load(named: "dice/d6", in: contentBundle)
        self.initialState = DieState(
            value: 1, parentID: .init(0), seatControl: .any,
            pose: .identity, entity: entity
        )
    }
}
```

### ControllingSeats

Restrict which players can interact with a piece via `seatControl`:
- `.any` -- any player
- `.restricted([seatID1, seatID2])` -- specific seats only
- `.current` -- only the seat whose turn it is
- `.inherited` -- inherits from parent equipment

### Equipment Hierarchy and Layout

Equipment can be parented to other equipment. Override `layoutChildren(for:visualState:)`
to position children. Return one of:
- `.planarStacked(layout:animationDuration:)` -- cards/tiles stacked vertically
- `.planarOverlapping(layout:animationDuration:)` -- cards fanned or overlapping
- `.volumetric(layout:animationDuration:)` -- full 3D layout

See [references/tabletopkit-patterns.md](references/tabletopkit-patterns.md) for card fan, grid, and overlap layout examples.

## Player Seats

Conform to `EntityTableSeat` and provide a pose around the table:

```swift
struct PlayerSeat: EntityTableSeat {
    var id: TableSeatIdentifier
    var initialState: TableSeatState
    var entity: Entity

    init(index: Int, pose: TableVisualState.Pose2D) {
        self.id = TableSeatIdentifier(index)
        self.entity = Entity()
        self.initialState = TableSeatState(pose: pose, context: 0)
    }
}
```

Claim a seat before interacting: `game.claimAnySeat()`, `game.claimSeat(matching:)`,
or `game.releaseSeat()`. Observe changes via `TabletopGame.Observer.playerChangedSeats`.

## Game Actions and Turns

### Built-in Actions

Use `TabletopAction` factory methods to modify game state:

```swift
// Move equipment to a new parent
game.addAction(.moveEquipment(matching: pieceID, childOf: targetID, pose: newPose))

// Flip a card face-up
game.addAction(.updateEquipment(card, faceUp: true))

// Update die value
game.addAction(.updateEquipment(die, value: 6))

// Set whose turn it is
game.addAction(.setTurn(matching: TableSeatIdentifier(1)))

// Update a score counter
game.addAction(.updateCounter(matching: counterID, value: 100))

// Create a state bookmark (for undo/reset)
game.addAction(.createBookmark(id: StateBookmarkIdentifier(1)))
```

### Custom Actions

For game-specific logic, conform to `CustomAction`:

```swift
struct CollectCoin: CustomAction {
    let coinID: EquipmentIdentifier
    let playerID: EquipmentIdentifier

    init?(from action: some TabletopAction) {
        // Decode from generic action
    }

    func validate(snapshot: TableSnapshot) -> Bool {
        // Return true if action is legal
        true
    }

    func apply(table: inout TableState) {
        // Mutate state directly
    }
}
```

Register custom actions during setup:

```swift
setup.register(action: CollectCoin.self)
```

### Score Counters

```swift
setup.add(counter: ScoreCounter(id: .init(0), value: 0))
// Update: game.addAction(.updateCounter(matching: .init(0), value: 42))
// Read:   snapshot.counter(matching: .init(0))?.value
```

### State Bookmarks

Save and restore game state for undo/reset:

```swift
game.addAction(.createBookmark(id: StateBookmarkIdentifier(1)))
game.jumpToBookmark(matching: StateBookmarkIdentifier(1))
```

## Interactions

### TabletopInteraction.Delegate

Return an interaction delegate from the `.tabletopGame` modifier to handle
player gestures on equipment:

```swift
.tabletopGame(game.tabletopGame, parent: game.renderer.root) { value in
    if game.tabletopGame.equipment(of: GameDie.self, matching: value.startingEquipmentID) != nil {
        return DieInteraction(game: game)
    }
    return DefaultInteraction(game: game)
}
```

### Handling Gestures and Tossing Dice

```swift
class DieInteraction: TabletopInteraction.Delegate {
    let game: Game

    func update(interaction: TabletopInteraction) {
        switch interaction.value.phase {
        case .started:
            interaction.setConfiguration(.init(allowedDestinations: .any))
        case .update:
            if interaction.value.gesture?.phase == .ended {
                interaction.toss(
                    equipmentID: interaction.value.controlledEquipmentID,
                    as: .cube(height: 0.02, in: .meters)
                )
            }
        case .ended, .cancelled:
            break
        }
    }

    func onTossStart(interaction: TabletopInteraction,
                     outcomes: [TabletopInteraction.TossOutcome]) {
        for outcome in outcomes {
            let face = outcome.tossableRepresentation.face(for: outcome.restingOrientation)
            interaction.addAction(.updateEquipment(
                die, rawValue: face.rawValue, pose: outcome.pose
            ))
        }
    }
}
```

### Tossable Representations

Dice physics shapes: `.cube` (d6), `.tetrahedron` (d4), `.octahedron` (d8),
`.decahedron` (d10), `.dodecahedron` (d12), `.icosahedron` (d20), `.sphere`.
All take `height:in:` (or `radius:in:` for sphere) and optional `restitution:`.

### Programmatic Interactions

Start interactions from code: `game.startInteraction(onEquipmentID: pieceID)`.

See [references/tabletopkit-patterns.md](references/tabletopkit-patterns.md) for group
toss, predetermined outcomes, interaction acceptance/rejection, and destination
restriction patterns.

## RealityKit Rendering

Conform to `EntityRenderDelegate` to bridge state to RealityKit. Provide a
`root` entity. TabletopKit automatically positions `EntityEquipment` entities.

```swift
class GameRenderer: EntityRenderDelegate {
    let root = Entity()

    func onUpdate(timeInterval: Double, snapshot: TableSnapshot,
                  visualState: TableVisualState) {
        // Custom visual updates beyond automatic positioning
    }
}
```

Connect to SwiftUI with `.tabletopGame(_:parent:automaticUpdate:)` on a
`RealityView`:

```swift
struct GameView: View {
    let game: Game

    var body: some View {
        RealityView { content in
            content.entities.append(game.renderer.root)
        }
        .tabletopGame(game.tabletopGame, parent: game.renderer.root) { value in
            GameInteraction(game: game)
        }
    }
}
```

Debug outlines: `game.tabletopGame.debugDraw(options: [.drawTable, .drawSeats, .drawEquipment])`

## Group Activities Integration

TabletopKit integrates directly with GroupActivities for FaceTime-based
multiplayer. Define a `GroupActivity`, then call `coordinateWithSession(_:)`.
TabletopKit automatically synchronizes all equipment state, seat assignments,
actions, and interactions. No manual message passing required.

```swift
import GroupActivities

struct BoardGameActivity: GroupActivity {
    var metadata: GroupActivityMetadata {
        var meta = GroupActivityMetadata()
        meta.type = .generic
        meta.title = "Board Game"
        return meta
    }
}

@Observable
class GroupActivityManager {
    let tabletopGame: TabletopGame
    private var sessionTask: Task<Void, Never>?

    init(tabletopGame: TabletopGame) {
        self.tabletopGame = tabletopGame
        sessionTask = Task { @MainActor in
            for await session in BoardGameActivity.sessions() {
                tabletopGame.coordinateWithSession(session)
            }
        }
    }

    deinit { tabletopGame.detachNetworkCoordinator() }
}
```

Implement `TabletopGame.MultiplayerDelegate` for `joinAccepted()`,
`playerJoined(_:)`, `didRejectPlayer(_:reason:)`, and
`multiplayerSessionFailed(reason:)`. See
[references/tabletopkit-patterns.md](references/tabletopkit-patterns.md) for custom
network coordinators and arbiter role management.

## Common Mistakes

- **Forgetting platform restriction.** TabletopKit is visionOS-only. Do not
  conditionally compile for iOS/macOS; the framework does not exist there.
- **Skipping seat claim.** Players must call `claimAnySeat()` or `claimSeat(_:)`
  before interacting with equipment. Without a seat, actions are rejected.
- **Mutating state outside actions.** All state changes must go through
  `TabletopAction` or `CustomAction`. Directly modifying equipment properties
  bypasses synchronization.
- **Missing custom action registration.** Custom actions must be registered with
  `setup.register(action:)` before creating the `TabletopGame`. Unregistered
  actions are silently dropped.
- **Not handling action rollback.** Actions are optimistically applied and can be
  rolled back if validation fails on the arbiter. Implement
  `actionWasRolledBack(_:snapshot:)` to revert UI state.
- **Using wrong parent ID.** Equipment `parentID` in state must reference a
  valid equipment ID (typically the table or a container). An invalid parent
  causes the piece to disappear.
- **Ignoring TossOutcome faces.** After a toss, read the face from
  `outcome.tossableRepresentation.face(for: outcome.restingOrientation)` rather
  than generating a random value. The physics simulation determines the result.
- **Testing multiplayer in Simulator.** Group Activities do not work in Simulator.
  Multiplayer requires physical Apple Vision Pro devices on a FaceTime call.

## Review Checklist

- [ ] `import TabletopKit` present; target is visionOS 2.0+
- [ ] `TableSetup` created with a `Tabletop`/`EntityTabletop` conforming type
- [ ] All equipment conforms to `Equipment` or `EntityEquipment` with correct state type
- [ ] Seats added and `claimAnySeat()` / `claimSeat(_:)` called at game start
- [ ] All custom actions registered with `setup.register(action:)`
- [ ] `TabletopGame.Observer` implemented for reacting to confirmed actions
- [ ] `EntityRenderDelegate` or `RenderDelegate` connected
- [ ] `.tabletopGame(_:parent:automaticUpdate:)` modifier on `RealityView`
- [ ] `GroupActivity` defined and `coordinateWithSession(_:)` called for multiplayer
- [ ] Group Activities capability added in Xcode for multiplayer builds
- [ ] Debug visualization (`debugDraw`) disabled before release
- [ ] Tested on device; multiplayer tested with 2+ Apple Vision Pro units

## References

- [references/tabletopkit-patterns.md](references/tabletopkit-patterns.md) -- extended patterns for observer implementation, custom actions, dice simulation, card overlap, and network coordination
- [Apple Documentation: TabletopKit](https://sosumi.ai/documentation/tabletopkit)
- [Creating tabletop games (sample code)](https://sosumi.ai/documentation/tabletopkit/creating-tabletop-games)
- [Synchronizing group gameplay with TabletopKit (sample code)](https://sosumi.ai/documentation/tabletopkit/synchronizing-group-gameplay-with-tabletopkit)
- [Simulating dice rolls as a component for your game (sample code)](https://sosumi.ai/documentation/tabletopkit/simulating-dice-rolls-as-a-component-for-your-game)
- [Implementing playing card overlap and physical characteristics (sample code)](https://sosumi.ai/documentation/tabletopkit/implementing-playing-card-overlap-and-physical-characteristics)
- [WWDC24 session 10091: Build a spatial board game](https://sosumi.ai/videos/play/wwdc2024/10091/)