Danielius Studio · iOS

Pink Trail

Daily trajectory from a video. On-device.

Pick a short video of a thrown ball, a bird, a skater, a stone skipping a pond. Pink Trail uses Apple's Vision framework on your device to find the longest motion path, fit a parabola through it, and save the trajectory as a single thumbnail with the curve and equation overlaid. By December, a year of trails fills a printable wall.

How it works

Open Pink Trail. Pick a short video clip through Apple's system video picker.
Vision's on-device VNDetectTrajectoriesRequest scans the clip and finds the longest parabolic motion path.
Pink Trail fits a parabola to the path, snapshots the middle frame, and overlays the polyline plus the parabola equation.
Pin the Lock Screen widget to see your most recent trajectory at a glance. Open the app in late December to print a year wall of every saved trail.

What stays on your device

No accounts, no email, no signup.
No analytics, no third-party SDKs.
Videos are read only through Apple's system picker, which means you pick each one by hand.
Trajectory polylines, parabola equations, and middle-frame thumbnails are stored on-device with SwiftData. Nothing leaves your phone.
The only network calls Pink Trail makes are to Apple's StoreKit when you choose to subscribe or buy Lifetime.

Pricing

A handful of trails per month, free. Pro unlocks unlimited trails, the year-end wall, and the Lock Screen widget:

Pro Monthly: $3/month, with a 14-day free intro on the first subscription.
Pro Annual: $13/year.
Pro Lifetime: $29 one-time.

All purchases are handled by Apple and managed under your Apple ID. Pro is Family-Shareable through Apple's standard Family Sharing.

Support

Questions, bugs, or a feature request? support@danielius.studio. Replies typically within a day or two.

To restore a purchase on a new device, open Pink Trail, tap the settings icon, open the paywall, and tap Restore Purchases. Apple will re-verify your Apple ID's entitlements.

To cancel an auto-renewing subscription, open the Settings app on iPhone, tap your name at the top, then Subscriptions, then Pink Trail Pro.