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Sunnook app icon (1024 × 1024)
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Inspiration
Knowing where the sun is in the sky is not the same as knowing when it can reach a particular spot inside a room. Sunnook brings that question down to a human scale: where should a plant, desk, or reading chair go, and how might that change through the year?
What it does
Sunnook is an iPhone and iPad app for exploring theoretical direct sunlight inside a modeled room. Start with the sample room, draw a room from measurements, use a photo as a reference, or scan with Apple RoomPlan on a compatible LiDAR device. Review the dimensions, windows, location, and north direction, then move through the day to see where clear-sky direct sunlight can land.
Sun Pins track favorite spots. Sunnook Pro adds unlimited saved rooms, an annual Sun Calendar, printable Light Maps, eight-second sunlight time-lapse exports, and optional local alerts before a modeled Sun Pin interval. The sample experience and one saved room are free; Pro is a lifetime in-app purchase powered by RevenueCat.
Sunnook is a planning tool, not a weather forecast or a guarantee of observed brightness. The model excludes clouds, exterior obstructions, curtains, glazing loss, tint, and reflected light.
How it was built
The app uses Swift and SwiftUI for the native interface, RealityKit for spatial visualization, and Apple's ARKit and RoomPlan for supported room capture. Solar calculations combine the reviewed room geometry, windows, orientation, date, and location to model direct-sun opportunities. RevenueCat manages the Pro purchase, entitlement, and restore flow.
The room workflow is deliberately reviewable: capture is a starting point, and the user confirms the inputs before relying on the model. Manual setup keeps the core experience available without LiDAR.
Challenges
The difficult part is connecting a room model to an understandable, trustworthy result. Dimensions, north, window geometry, and photo calibration all affect what a sunlight preview means. Sunnook makes those inputs visible and editable instead of presenting a scan as unquestionable ground truth.
Another challenge is communicating the boundary between direct-sun modeling and the richer appearance of real light. Soft edges, reflections, window frames, and weather matter in real rooms, so the interface explains what is and is not modeled.
Accomplishments
Sunnook shipped its first public App Store release during Shipaton, on August 26, 2026. The app combines a free sample experience, reviewable room setup, spatial sunlight exploration, and a RevenueCat-powered lifetime Pro upgrade in one native iPhone and iPad product.
Lessons
A useful spatial tool needs more than an attractive visualization: people need to understand the inputs and limits of the result. Reviewable room setup, clear free and Pro boundaries, and concrete sunlight-planning use cases are central to Sunnook's product design.
What's next
Next areas to explore include testing modeled sunlight against observations in real rooms, improving capture and photo-alignment guidance, and refining the experience from user feedback without overstating the model's accuracy.
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