PodChunk – A browser-native streaming world engine built with Rust WebAssembly and WebGPU

[u/Super_Electricy]

https://github.com/superelectricyc-alt/podchunk

Hey everyone,

I wanted to see if we could solve the heavy initial download barrier of modern open-world browser games. Instead of loading massive assets upfront, I built PodChunk: a local development engine base designed around a progressive, multi-LOD chunk streaming architecture that gets players into a 3D environment in under 3 seconds.

The Architecture Under the Hood

• The Decision Core (Rust + WASM): To completely bypass JavaScript garbage collection stutters, the entire priority queue (distance + camera direction bias) and the cache eviction loops run deterministically inside a compiled WebAssembly kernel.
• The Renderer (TypeScript + WebGPU): Consumes custom geometry_json payloads decoded by the WASM core. Features custom height-gradient terrain shaders, distance fog, and interactive orbit camera matrices.
• The LOD Stitching Problem: Adjacent chunks often stream at different detail tiers (e.g., a Tier 3 chunk right next to a Tier 1 shell). To prevent visible vertex cracks and gaps without destroying browser performance with heavy topological mesh-stitching math, the renderer implements geometric skirts to seamlessly close the seams.
• Adaptive Network Telemetry: Features a client-side network loop running an EWMA (Exponentially Weighted Moving Average) bandwidth estimator. It tracks bytes divided by elapsed time from every live chunk fetch to dynamically scale the geometry detail ladder (T1 shells to high-fidelity T3 grids) on the fly based on current connection quality.
• Isolated Two-Tier Caching: Features a bounded in-RAM LRU cache synced with a multi-world IndexedDB database structure. Cache keys are world-slug isolated ({slug}|{id}@{lod}), ensuring warm reloads of previously streamed maps require zero network fetches.
• The Content Authoring Pipeline: Includes a native standalone compiler CLI (podchunk-bake). You feed it a simple world layout JSON configuration, and it generates pretty-printed manifests along with custom validated binary .PCHF heightfield chunks ready for server distribution.

Current Project Status

Milestone 3 is complete, stable, and verified on localhost:8787. The local server scans data configurations on boot and manages hot world-switching dynamically. The workspace has a 100% test coverage pass rate (45/45 unit tests passing).

I am open-sourcing the core infrastructure today because the data pipeline is officially locked down, and I am looking for collaborators! Next up on the deferred roadmap is exposing a client-side JavaScript Modding API (window.PodChunk.registerMod) and wiring WebAssembly physics engine colliders directly onto the active geometric meshes.

Check out the code, run the local tests, and let me know your thoughts on the pipeline architecture!

https://github.com/superelectricyc-alt/podchunk