Propel SDK

Motion input for Apple platforms. No extra hardware required.

Turn the iPhone everyone already owns into a motion controller. Face expressions, head movement, body tracking — captured via ARKit, delivered as a clean Swift API.

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How It Works
Three steps. Zero configuration.
From camera capture to game input — Propel handles the entire pipeline.

Capture

ARKit face & body tracking at 60fps. 52 blendshapes, head rotation, eye tracking. 91 body joints with multi-player support.

Stream

Zero-config Bonjour discovery. WebSocket streaming over local WiFi. Sub-50ms latency. Port 5070.

Play

23 semantic gestures with cooldowns. Multi-player tracking. Three-layer API — raw data, gestures, or player events.

Developer API
Three layers.
One import.

Raw tracking data for custom logic. Semantic gestures for quick integration. Player events for multiplayer. Use what you need.

The API is identical whether tracking runs locally (ARKit on-device) or remotely (iPhone over WiFi). Your code doesn't change.

GameScene.swift 
import PropelReceiver

let propel = PropelReceiver.shared

// Layer 1 — Raw data
propel.onFrame = { frame in
    let jawOpen = frame.blendshapes.jawOpen
    let pitch = frame.headRotation.pitch
}

// Layer 2 — Semantic gestures
propel.onGesture = { event in
    switch event.gesture {
    case .smile:    score += 1
    case .jump:     player.jump()
    case .headNod:  confirmAction()
    default:       break
    }
}

// Layer 3 — Multiplayer
propel.onPlayerJoined = { player in
    print("\(player.id) joined")
}

propel.startDiscovery()
Built-in Gestures
23 gestures. Ready to use.

All gestures include configurable thresholds, cooldowns, and temporal pattern detection.

Face — Front Camera, TrueDepth
mouthOpen mouthClosed smile frown eyebrowRaise eyeWide eyeSquint headNod headShake lookLeft lookRight lookUp lookDown
Body — Rear Camera, Up to 4 Players
jump duck armsUp armsOut lean(.left) lean(.right) stepLeft stepRight wave clap
Architecture
Clean separation. Zero coupling.

The tracking layer has zero knowledge of what the receiver does with data. Pairing is automatic via Bonjour.

PropelTracker
iOS
ARKit face + body capture
WebSocket server
WebSocket · 60fps
PropelReceiver
iOS · tvOS · macOS
Gesture engine
Player management
PropelCore
All Platforms
Models · Gestures · Protocol · Discovery
Installation
Add one package. Pick your modules.
Package.swift 
// Swift Package Manager
dependencies: [
    .package(
        url: "https://github.com/propelsdk/propel-sdk.git",
        from: "0.2.0"
    )
]
Module Platforms Purpose
PropelCore iOS, tvOS, macOS Shared models, gestures, protocol
PropelTracker iOS ARKit capture, WebSocket streaming
PropelReceiver iOS, tvOS, macOS Gesture engine, player management
iOS 16+
tvOS 16+ · macOS 13+
iPhone XS
or newer (TrueDepth)
Swift 5.9+
strict concurrency