# mmp/pbrt-v4

Source code to pbrt, the ray tracer described in the forthcoming 4th edition of the "Physically Based Rendering: From Theory to Implementation" book.

Repository: https://github.com/mmp/pbrt-v4
Canonical: https://ross.abutalabs.com/products/pbrt-v4
Homepage: https://pbrt.org
Language: C++
License: Apache-2.0
License Family: permissive
Last push: 2026-06-14T23:50:35+00:00

## Health v2 (maintenance only)
Score: 71/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 87, release rhythm 35, longevity 100
- inputs: {"age_days": 3323, "days_push": 80, "days_rel": null, "gap_med": null, "n_releases_24m": 0}
- flags: no_releases
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 3683, forks 627 (observed 2026-08-28T04:08:13.815673+00:00)

## What it is
pbrt-v4 is the C++ physically based ray tracing system accompanying the fourth edition of the book 'Physically Based Rendering: From Theory to Implementation'. It supports spectral rendering, modern volumetric scattering, and GPU rendering via CUDA/OptiX.

## Use cases
- render photorealistic images with a physically based ray tracer
- learn how a production-quality renderer is implemented
- render scenes on NVIDIA GPUs with CUDA and OptiX
- do spectral and volumetric rendering research
- teach a computer graphics rendering course
- experiment with path tracing integrators

## When to choose
- you want a well-documented, academically grounded renderer tied to a free textbook
- you need spectral rendering or advanced volumetric scattering
- you have NVIDIA GPUs and want GPU-accelerated path tracing
- you are teaching or studying physically based rendering

## When to avoid
- you need a production film renderer with a large artist toolchain
- you require GPU rendering on non-NVIDIA hardware
- you want a real-time game engine renderer

## Facets
- artifact type: application
- maturity: stable
- function: graphics, simulation, gpu-computing
- domain: graphics, computer-vision, education
- platform: windows, cpp
- tags: ray-tracing, physically-based-rendering, spectral-rendering, optix, cuda, path-tracing, rendering, linux, macos, gpu

## Member repositories
- mmp/pbrt-v4 (main) score 71

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:08:13.815673+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-29T18:31:12.029356+00:00, confidence not recorded.
  - readme: https://github.com/mmp/pbrt-v4 (fetched 2026-08-28T04:08:13.815673+00:00, sha 8099cd8e2403)
  - homepage: https://pbrt.org (fetched 2026-08-29T09:25:01.326615+00:00, sha 3b7e1144d278)
  - site_page: https://pbrt.org/faqs.html (fetched 2026-08-29T09:25:01.336602+00:00, sha 706e063e6367)
- Data as of 2026-08-30T08:39:29.467469+00:00.