AetherTrace

A premium, physically-based path tracer written in Rust. Renders four built-in scenes with next-event estimation (NEE), multiple importance sampling (MIS), a binned-SAH BVH, PBR metals, dielectrics, procedural HDR skies, and tone-mapped progressive output — all multi-threaded with Rayon.

Features

• Path tracing core
  • Next-event estimation for area lights (uniform light sampling + power-heuristic MIS)
  • MIS with the environment map; Russian-roulette path termination
  • Correct MIS-weighted contributions when BSDF-sampled rays hit area lights (specular highlights)
  • Progressive rendering with interactive checkpoints
• Materials
  • Lambert, checkerboard, emissive
  • GGX PBR (metallic + roughness, Schlick Fresnel, Smith masking/shadowing)
  • Dielectric (Fresnel reflection/refraction, total internal reflection)
• Acceleration
  • Binned surface-area-heuristic (SAH) BVH with in-place primitive partition
  • Verified against brute-force traversal (0 mismatches on all scenes)
• Camera & environment
  • Pinhole / depth-of-field, arbitrary look-at
  • Procedural HDR sky with sun disk + analytic sampling, or constant/studio env
• Output & CLI
  • PNG (ACES / neutral / none tonemapping, auto or manual exposure) and Radiance .hdr
  • Parallel rendering, quality presets, reproducible seeds

Usage

aethertrace [OPTIONS]

Usage: aethertrace [OPTIONS]

Options:
  -c, --scene <SCENE>          Scene to render: cornell | spheres | studio | sunset [default: spheres]
  -w, --width <WIDTH>          Image width in pixels [default: 1280]
  -H, --height <HEIGHT>        Image height in pixels [default: 800]
  -s, --samples <SAMPLES>      Total samples per pixel [default: 256]
      --max-depth <MAX_DEPTH>  Max path depth [default: 16]
      --threads <THREADS>      Threads to use (0 = all available) [default: 0]
      --exposure <EXPOSURE>    Photographic exposure in stops (default: auto) [default: NaN]
      --tonemap <TONEMAP>      Tonemapper: aces | neutral | none [default: aces]
  -o, --out <OUT>              Output base path (final images written as <out>.png and <out>.hdr) [default: render]
      --passes <PASSES>        Number of progressive checkpoints [default: 4]
      --seed <SEED>            RNG seed for reproducibility [default: 42]
      --preset <PRESET>        Quick quality preset [default: ""]
  -h, --help                   Print help
  -V, --version                Print version

Examples

# Quick preview
aethertrace --preset fast -c cornell

# Final-quality render of the studio scene
aethertrace -c studio -w 1920 -H 1080 -s 2048 --passes 4

# Ultra-quality sunset, custom output, fixed exposure
aethertrace -c sunset --preset ultra -o out/sunset --exposure 1.0

# Reproducible render with a fixed seed
aethertrace -c spheres --seed 12345 -s 4096

Presets

Preset	Resolution	Samples	Passes
fast	640×400	64	2
final/high	1920×1080	2048	4
ultra	2560×1440	8192	6

Scenes

• cornell — classic Cornell box: white/red/green room, emissive ceiling panel, gold box, rotated gold box, glass sphere.
• spheres — checkerboard ground with glass, blue, gold, chrome, and plastic spheres under a procedural sky.
• studio — dark product studio: near-black PBR floor and backdrop, key softbox, cool rim lights, glass/gold/red spheres and a black plastic box.
• sunset — wide outdoor scene: warm sun disk, rocky ground, metal box, glass and red spheres.

Verification

examples/bvh_verify.rs compares the BVH against brute-force traversal for both closest-hit and shadow rays across 20 000 random rays per scene — all four scenes report 0 mismatches, including the tie-break on shared quad diagonals (lowest primitive index wins).

cargo run --release --example bvh_verify

Building

Requires Rust (edition 2024).

cargo build --release

License

MIT — see LICENSE.