v0.0.5

Added

• (pathtrace) expose GPU-port hooks — Sobol' direction numbers, sheen LUT, emissive light table, env-map CDFs, radiance_key, TraceScene::bvh
• (pathtrace) Arvo 1995 spherical-triangle light sampling
• (pathtrace) unbiased Monte Carlo path tracer backend (RenderBackend::PathTrace)
• (raycast) trace the prepared scene; native glTF Pbr with ray-traced shadows, reflection, refraction, MASK/BLEND
• (trace) ray-differential LOD, shadow transmittance, direct lighting, Snell/Fresnel helpers; share scanline Frame
• (trace) shared ray-tracing layer over PreparedScene
• camera target offset (pan), orthographic orbit zoom, Renderer::set_texture_resolver
• (scanline) port onto the prep layer — clipping, perspective-correct visibility buffer, glTF PBR, alpha modes, shadow maps, band-parallel
• public backend-agnostic scene preparation layer + public camera
• texture resolution + CPU sampler, HDR image + tone mapping
• Error::Backend for runtime backend failures (GPU adapter/device/readback)

Fixed

• (pathtrace) glTF back-face normal-map orientation on double-sided materials
• (scanline) crack-free shared edges + parallel display transform

Other

• (pathtrace) parallel display resolve (1080p image() in 7.8 ms)
• path tracer in README / CHANGELOG / BENCHMARKS; criterion pathtrace group
• raycast Pbr (shadows, reflection, refraction, MASK/BLEND), trace layer additions, raycast benchmarks
• (raycast) adaptive BVH builder, all-core tile workers; raycast PBR benches
• crate overview of the shared layers; BENCHMARKS for the prep-layer scanline
• README/CHANGELOG for the prep layer, textures, HDR, Pbr scanline; PBR bench rows
• shared procedural test scenes, image metrics, PBR property suite + raw goldens
• traverse via mesh3d's SAH Bvh::closest_hit / occluded

Added

• RenderBackend::PathTrace (pathtrace, registry name
  "pathtrace"): unbiased unidirectional Monte Carlo path tracer
  (Kajiya 1986). Next-event estimation to every KHR_lights_punctual
  light and to one power-sampled emissive triangle (spherical-triangle
  sampling, Arvo 1995, with a uniform-area fallback for tiny solid
  angles) or environment texel per vertex, power-heuristic MIS against BSDF
  sampling (Veach 1997), Russian roulette, optional firefly clamp.
  BSDF: glTF metallic-roughness with GGX visible-normal sampling
  (Heitz 2018), cosine diffuse and Fresnel-weighted lobe selection
  (mixture pdfs), KHR_materials_transmission (thin-walled and
  Walter 2007 rough refraction), _volume (Beer-Lambert), _ior,
  _specular, _clearcoat, _sheen (Charlie), emissive. MASK any-hit,
  BLEND stochastic transparency, normal maps, double-sided surfaces.
  Owen-scrambled Sobol' sequences (Burley 2020) with PCG-hash seeding
  and a documented dimension layout; deterministic output.
  RenderOptions::path_trace: PathTraceOptions (samples per pixel,
  max bounces, roulette start, clamp, seed, LightStrategy).

• Progressive PathTracer: sync / refine / image / hdr
  with radiance-aware reset; EnvironmentMap (equirectangular
  HdrImage, 2-D luminance CDF importance sampling);
  PathTraceRenderer.

• trace: shared ray-tracing layer (TraceScene world-space BVH
  with filtered closest / any-hit queries, surface interpolation,
  material evaluation at a hit, ray-cone texture LOD, Wächter-Binder
  ray offsets).

• dump_testscenes example takes an optional backend + spp.

• Public scene-preparation layer (prepare): PreparedScene —
  world-space de-indexed DrawItems (triangles / lines / points) with
  animation sampled at a time, morph weights, CPU skinning, generated
  flat normals / tangents, CCW-front winding; resolved material and
  texture tables; world-space KHR_lights_punctual lights
  (PreparedLight::sample = spec attenuation) with the options light as
  fallback; scene camera instances. Shared by every backend and the GPU
  backend.

• Public camera (camera::Camera): resolve (scene camera or
  auto-frame / orbit), from_scene_camera, projection_matrix /
  view_projection with DepthRange::{NegOneToOne, ZeroToOne}.

• Textures (texture): TextureResolver trait, TextureCache,
  RegistryTextureResolver (registry feature; decodes via an
  oxideav_core::RuntimeContext + oxideav-pixfmt), built-in raw RGBA8
  container, sRGB / linear mip chains, glTF-sampler CPU sampling
  (wrap modes, nearest / bilinear / trilinear, derivative LOD).

• HDR (hdr): HdrImage, Renderer::render_hdr, ToneMap::{Clamp, Reinhard, AcesFitted}, exposure.

• ShadingMode::Pbr in the scanline backend: glTF 2.0 Appendix B
  metallic-roughness BRDF (public brdf module), base colour /
  metallic-roughness / normal / occlusion / emissive textures, vertex
  colours, KHR_materials_unlit / _emissive_strength / _ior,
  multiple punctual lights + ambient, OPAQUE / MASK / BLEND (sorted,
  over-composited), double-sided vs back-face culling, optional shadow
  maps for directional / spot lights with PCF.

• RenderOptions: tone_map, exposure, time, animation,
  scene_camera, use_scene_lights, ambient, shadows,
  shadow_map_size, material_variant.

• RenderOptions::camera_target_offset pans the auto-frame / orbit
  camera; an orbit CameraSpec::distance now zooms orthographic
  views; Renderer::set_texture_resolver (default no-op, implemented
  by the scanline backend) gives any backend a texture decoder.

• Raycast ShadingMode::Pbr: the Whitted ray tracer now renders the
  shared PreparedScene (animation, morphs, skinning) through
  Camera::resolve and the new trace layer, evaluating the scanline
  glTF formulas at every hit (all texture slots, vertex colours, normal
  maps, KHR_texture_transform, unlit, emissive, double-sided /
  culled back faces) — pixel-identical to scanline without secondary
  rays — plus ray-traced hard shadows for every light type (MASK /
  BLEND / transmission aware), MASK any-hit filtering, BLEND by
  continued rays composited in linear space, Fresnel-weighted mirror
  reflection with a roughness cut-off, and refraction through
  KHR_materials_transmission (thin-walled) / KHR_materials_volume
  (Snell, total internal reflection, Beer–Lambert absorption).
  Texture LOD from ray differentials on camera rays, ray cones after
  bounces.

• RaycastRenderer: native render_hdr, set_texture_resolver,
  with_texture_resolver, texture_cache_mut.

• RenderOptions::max_ray_depth (default 4) and
  RenderOptions::reflection_roughness_cutoff (default 0.5).

• trace additions: TexLod::Grad + TraceScene::barycentric_differentials
  (ray differentials), material_oriented, shadow_transmittance,
  direct_light, with_build_options, reflect / refract /
  schlick / barycentric_of / pixel_spread.

• tests/raycast_pbr.rs: scanline parity on eight test scenes,
  shadow, reflection, refraction, MASK / BLEND, HDR and resolver tests.

• testscenes: procedural reference scenes + image metrics for
  cross-backend tests; tests/scanline_pbr.rs property suite with raw
  goldens; examples/dump_testscenes.

Changed

• Raycast backend rebuilt on the prep + trace layers: framing, posing
  and lighting match scanline / GPU; every mode resolves through the
  scanline frame contract (linear SSAA, tone map, verbatim
  background); 16×16 tiles on std::thread::scope workers with an
  atomic queue (deterministic); object-median BVH when few rays per
  triangle are traced, binned SAH otherwise. Legacy modes keep their
  output (Phong keeps its Whitted rays). Lines / points stay
  invisible to rays.
• Scanline backend rebuilt on the prep layer: homogeneous frustum
  clipping (triangles crossing the near plane are clipped instead of
  dropped), perspective-correct interpolation, top-left fill rule
  (crack-free shared edges), visibility buffer with one shade per
  pixel in linear f32, premultiplied SSAA resolve, band-parallel
  std::thread::scope workers with deterministic output.
  ScanlineRenderer now owns a TextureCache
  (with_texture_resolver). Legacy shading modes keep their output.