tabletopkit

TabletopKit

Build visionOS board games whose synchronized state changes flow through TabletopAction and render with RealityKit. The availability matrix below owns version details.

Contents

• Setup
• Game Configuration
• Table and Board
• Equipment (Pieces, Cards, Dice)
• Player Seats
• Game Actions and Turns
• Interactions
• RealityKit Rendering
• Group Activities Integration
• Common Mistakes
• Review Checklist
• References

Setup

Simulator supports single-player layout testing, 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 table, piece, card, and dice USDZ assets in a RealityKit content bundle.

Key Types Overview

Game Configuration

Build and validate a game in this order:

1. Define the tabletop, equipment, and seats.
2. Configure TableSetup and register every custom action type.
3. Create the game, attach its observer and renderer, claim a seat, and establish automatic or manual update handling.
4. Inspect the current snapshot for required equipment IDs, parents, seats, and counters before starting multiplayer. Fix the setup and rebuild if an invariant fails.

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)))

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.

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:

// 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:

Defining Equipment

// 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
• .restrictedCurrent([seatID1, seatID2]) -- specific seats only while they are in turn
• .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 for card fan, grid, and overlap layout examples.

Player Seats

Conform to EntityTableSeat and provide a pose around the table:

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:

// 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 when the availability matrix permits it. Custom action application and validation must depend only on the action data and the supplied TableState / TableSnapshot so every peer resolves the same result. Register custom action types during setup before dispatching them:

setup.register(action: CollectCoin.self)
game.addAction(CollectCoin(coinID: coinID, playerID: playerID))

Register each custom action type before dispatching it. See references/tabletopkit-patterns.md for full custom action and custom state examples.

Score Counters

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:

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

Bookmark restoration is asynchronous and network ordered. Wait for stateDidResetToBookmark, then read withCurrentSnapshot, rebuild local UI from that authoritative callback state, and validate the restored invariant. Do not inspect immediately after jumpToBookmark or enqueue another jump on mismatch. Load State Bookmarks and Undo for the observer reconciliation pattern.

Interactions

TabletopInteraction.Delegate

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

.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)
}

Use interaction.value.gesture for gesture-specific state. Avoid deprecated gesturePhase. For destination control, prefer interaction.setConfiguration(.init(allowedDestinations: ...)) when available rather than deprecated setAllowedDestinations(_:) or value.allowedDestinations.

Handling Gestures and Tossing Dice

Basic toss(equipmentID:as:) is core TabletopKit; the availability matrix owns advanced toss outcomes.

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 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.

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:

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.

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 for custom network coordinators and arbiter role management.

Common Mistakes

• 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. Register every custom action with setup.register(action:) before use.
• 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.
• Ignoring discarded actions when available. Implement actionWasDiscarded(_:) when local action queue pressure matters; it is called for local actions that cannot be enqueued.
• 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

• The centralized platform/availability matrix is applied
• 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 reconciles confirmed, rolled-back, discarded, and bookmark-reset outcomes with the current snapshot
• EntityRenderDelegate or RenderDelegate connected
• .tabletopGame(_:parent:automaticUpdate:) modifier on RealityView
• GroupActivity defined and coordinateWithSession(_:) called; multiplayer described as Group Activities/SharePlay synchronization
• Group Activities capability added in Xcode for multiplayer builds
• Debug visualization (debugDraw) disabled before release
• Device notes state Simulator is single-player only; multiplayer requires 2+ Apple Vision Pro units on FaceTime

References

• references/tabletopkit-patterns.md -- extended patterns for observer implementation, custom actions, dice simulation, card overlap, and network coordination
• Apple Documentation: TabletopKit, Creating tabletop games, Synchronizing group gameplay
• Simulating dice rolls, Implementing playing card overlap
• WWDC24 session 10091: Build a spatial board game