💡 Inspiration
Bedřich Smetana composed his magnum opus, Vltava, in complete and profound deafness. He never heard the orchestral performance with his physical ears — he perceived its spatial flow, acoustic vibrations, and fluid dynamics purely in his mind and soul.
In an era dominated by heavy app downloads, brittle cloud APIs, and clunky handheld controllers, we created Asterisk: Vltava. Our mission is to transform classical music and human communication into a tactile, spatial, and visual experience accessible to everyone — especially the deaf, hard of hearing, and blind. We set out to prove that spatial computing can be controller-free, in-memory private, and mathematically verifiable.
⚙️ What it does
Asterisk: Vltava is an immersive WebXR spatial journey and sign-language communication suite running natively inside the Meta Quest Browser:
- Spatial Symphony & Fluid Dynamics: Follow the journey of a single droplet from the cold springs of the Šumava forest, through river rapids and ancient castles, all the way to Prague's Charles Bridge. Orchestral acoustics are rendered via 3D HRTF spatial audio paired with resonant visual wave particles.
- Deaf Composer Avatar (Bedřich Smetana): An interactive 3D historical avatar communicates with the user in Czech Sign Language (ČZJ) and daktyl finger alphabet, expressing musical themes through canonical spatial gestures.
- Hands-First Interaction: 100% controller-free. Users sculpt soundwaves, redirect river currents, and converse with the avatar using natural Meta Horizon hand tracking.
- Engineered for Comfort ("Airplane Seat" & "Bus Stop" Tests):
- Airplane Seat: The entire experience operates in a comfortable 60 cm bounding box — fully functional while seated without aggressive arm swinging.
- Bus Stop: Instant zero-install access via WebXR (< 2 seconds load time) without waiting for multi-gigabyte APK installs.
🛠️ How we built it
We combined safety-critical aerospace verification with lightweight spatial web graphics:
- Formally Verified Kinematics (Ada/SPARK 2022): The 19 canonical handshapes and skeletal constraints are proven with GNATprove (SMT solvers Z3 and CVC5). 100% absence of runtime errors (AoRTE), guaranteeing zero anatomical joint collisions or crashes.
- Bare-Metal Shadow Node (Rust + WASM): High-speed 120 FPS animation pipeline with zero Garbage Collection jitter and in-memory tandem failover.
- Spatial Audio & WebXR Runtime: Three.js / WebXR environment tightly integrated with Meta Horizon OS Hand Tracking API, custom fluid shaders, and binaural audio.
- Zero-Trace In-Memory Architecture (Ash Sweeper Protocol): Strict privacy-first design. All gesture tracking, biometric signals, and conversation frames live exclusively in volatile RAM — zero disk persistence.
🧗 Challenges we ran into
- Anatomical Precision in 3D: Enforcing mathematical joint boundaries from Ada/SPARK onto rigged 3D models while preserving the natural micro-motorics of sign language.
- Mobile Standalone Performance: Maintaining a locked 90–120 FPS on Meta Quest hardware while calculating fluid particle physics and dual-hand skeletal transforms concurrently.
- Air-Gapped Privacy: Maintaining a strict zero-disk footprint while dynamically synthesizing streaming transcripts into real-time gestures.
🏆 Accomplishments that we're proud of
- 100% Formal Verification: All verification conditions proven with mathematical certainty — zero runtime panics, zero memory overflows.
- Historic Accessibility Bridge: Honoring Bedřich Smetana's historic triumph over hearing loss by turning his music into a living, visual sign-language symphony.
- Sovereign Execution: Capable of running locally on battery and self-hosted solar hardware without reliance on centralized clouds.
📚 What we learned
High art and formal mathematics belong together. Ada/SPARK's rigid contract discipline provides the rock-solid foundation that allows generative AI, spatial fluid physics, and human expression to flourish without breaking.
🚀 What's next for Asterisk: Vltava
- Full multi-movement orchestral expansion across Smetana's entire Má vlast cycle (Vyšehrad, Šárka, Z českých luhů a hájů).
- Live two-way spatial telepresence connecting deaf and hearing audiences in synchronized WebXR concert halls.
- Releasing the open-source SPARK kinematics specification for universal robotic sign-language translation.
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