rust-gameboy

A WebGPU + Rust + WASM single-page app that renders a Game Boy with modern physically-based shading: Cook-Torrance / GGX, multi-scatter energy compensation, split-sum IBL from a real HDRI, a Filament-style clear coat layer over the LCD perspex, soft contact shadow on a white page, Khronos PBR Neutral tonemap, and orbit camera controls.

Prerequisites

• Rust 1.78+ with the wasm32-unknown-unknown target
  rustup target add wasm32-unknown-unknown
• wasm-pack
cargo install wasm-pack
• A static HTTP server (Python’s built-in works fine)
• A WebGPU-capable browser:
  • Chrome / Edge 113+
  • Safari 18+ (or Safari Technology Preview)

Build & run

./build.sh                 # wasm-pack build --target web --release → ./pkg
python3 -m http.server 8080
open http://127.0.0.1:8080/

For an iteration loop during development, ./build.sh dev is much faster.

Controls

What’s in here

Most of the interesting work is done at build time so the runtime can fit in a single static page:

• build.rs — parses the OBJ, swizzles Z-up → Y-up, weld + cleans triangles, generates MikkTSpace tangents, traces 256-sample ambient occlusion against the body BVH, bakes a binary clear-coat UV mask for the LCD perspex region, runs a mip pyramid over every PBR map, and prebakes the HDR equirect into a Rgba16Float blob. All of these land in OUT_DIR and get include_bytes!‘d into the wasm.
• src/shaders/mesh.wgsl — Cook-Torrance + Smith GGX, Schlick Fresnel, Fdez-Aguera multi-scatter compensation, split-sum IBL, Filament-style clear coat over the LCD region, Kaplanyan specular antialiasing, horizon + Lagarde specular occlusion, PCF 5×5 shadow sampling, Khronos PBR Neutral tonemap.
• src/ibl.rs — compute-shader irradiance / prefiltered cube / BRDF LUT bake at startup from the prebaked HDR equirect.
• src/shadow.rs — directional shadow map (2048² D32 once at startup; the scene is static), tight-fit ortho frustum from body AABB corners, soft contact-shadow disc on the white page with view-angle fade.

Milestones

• M1 — Project scaffold; canvas clears via WebGPU.
• M2 — Orbit camera + reference cube.
• M3 — Build-time OBJ bake + MikkTSpace tangents.
• M4 — Texture upload + base color.
• M5 — Full PBR maps + Cook-Torrance direct lighting.
• M6 — HDR environment → split-sum IBL.
• M7 — Multi-scatter compensation + clear coat on the LCD.
• M8 — Directional shadow map + soft contact shadow.
• M9 — Khronos PBR Neutral tonemap.
• M10 — Touch input, perf pass, screenshots.

Side milestones along the way:

• Build-time ambient-occlusion bake (BVH + 256-sample tracing).
• Specular antialiasing (Kaplanyan / Filament).

Screenshots

Stored in screenshots/ (drag a render off the page and drop it there to refresh).

Asset attribution

The Game Boy mesh and textures live in ../Yokoi/Assets/uploads_files_2642468_* and ship into ./assets/ at build time. They are not redistributed in this repo.