A Whitted-style CPU raytracer. Written to learn the math; never got to use any 3D matrices so I still don't know them.
Requires libpng and pkg-config (e.g. from MacPorts).
make # optimized build
make debug # FP exception traps, no -ffast-math
make check # render and assert exposure is in expected range
Does not work with -ffast-math (breaks infinity sentinel used for
max-distance tracking).
Outputs scene.bmp (tone-mapped 8-bit) and scene.hdr (Radiance HDR,
raw linear via RGBE encoding).
- Proper sRGB ↔ linear pipeline with noise-shaped dithering on output
- ACES filmic tone mapping via max-channel (preserves hue in highlights)
- Blackman-windowed sinc texture reconstruction (sharper than bilinear)
- Fresnel equations (unpolarized Rs/Rp, TIR handled)
- Per-channel Beer-Lambert absorption for coloured glass interiors
- Emission integral for volumetric self-glow (inky depth gradient)
- Backtracking shadow hack: caustics through glass without forward tracing
- Area light sampling (4 extra shadow rays for soft shadows/penumbras)
- SIMD-accelerated vector class (SSE on x86 via
-march=native) - POV-Ray parallel reference scene (photons + radiosity)
- Three.js WebGL preview
- No BVH or spatial acceleration — fine for 6 primitives
- Spheres and planes only
- No scene file format
- Texture minification needs mipmaps/ray differentials (current sinc filter is a fixed support, looks bad if textures are effectively downsized)
- Whitted-style transport: no path tracing, no proper GI