tabletopkit

SKILL.md

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

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

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

import TabletopKit in source files that define game logic.

import RealityKit for entity-based rendering.

For multiplayer, add the Group Activities capability in Signing &
Capabilities.

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.

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.

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:

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

// 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 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:

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:

setup.register(action: CollectCoin.self)

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))

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)
}

Handling Gestures and Tossing Dice

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

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 -- extended patterns for observer implementation, custom actions, dice simulation, card overlap, and network coordination

Apple Documentation: TabletopKit

Creating tabletop games (sample code)

Synchronizing group gameplay with TabletopKit (sample code)

Simulating dice rolls as a component for your game (sample code)

Implementing playing card overlap and physical characteristics (sample code)

WWDC24 session 10091: Build a spatial board game