034 · LUXCORERENDER
— The integrator menu, in concert —
Project Lavos · The Stack
Plate XXXIV · Score for Six Integrators

Coniunctio luminum.

— THE JOINING OF LIGHTS —

the ensemble.

LuxRender community  ·  forked from PBRT · 2008  ·  rewritten as LuxCoreRender · 2017

GPLv3 · OPENCL + CPU · UNBIASED · SPECTRAL · BLENDER-NATIVE

Most renderers ship one integrator and ask you to trust it. LuxCore ships six, and asks you which class of light path you mean to capture. Path tracing handles the easy ones. VCM, the soloist, picks up what nobody else can — the specular-diffuse-specular, the caustic through curved glass, the path that needs both ends to grow toward each other. Pick your integrator. The score is open.

— Plate XXXIV · Score for the Light-Transport Ensemble — after the LuxCore integrator menu
Easy ⟶ ⟵ Pathological L · D · E L · D · D · E L · S · D · E L · D · S · D · E L · S · D · S · E caustic · curved — light-path classes (Heckbert notation) — i. Path Tracing PT · forward 𝄻 𝄻 𝄻 ii. Bidir. BIDIR · two paths · MIS 𝄻 iii. Photon Map PMV · density estimation ♦ ♦ ♦ ♦ iv. VCM SOLOIST · vertex connection + merging ♦ ♦ ♦ ♦ — omnia — v. Metropolis MLT · mutation in path space vi. Hybrid BIDIR + photon · pragmatic ♦ ♦ ♦ 𝄻
diffuse — solid note
indirect — open note
♦specular path
soloist — VCM coverage
𝄻rest — integrator silent

The score is the menu. PT plays the easy notes; VCM picks up the rest. There is no single integrator that solves all light transport; LuxCore's choice was to ship the whole orchestra and trust you to conduct.

This is what an open-source production renderer looks like: not the renderer that hides choices, but the renderer that makes them nameable.

Roster · the Integrator Menu six instruments, one performance
First Violin
Path Tracing · PT
A single ray from the camera, bouncing at random until it finds a light. Reliable, easy to parallelise, terrible at caustics.
— L · D · E paths only
Second Violin
Bidirectional · BIDIR
Grow two paths — one from the camera, one from each light — and connect every vertex. MIS combines them. Harder light, cleaner result.
— L · S · D · E now possible
Cello
Photon Map · PMV
Shoot photons from lights, store them in the scene, gather density at each shading point. Caustics fall out for free; bias is the price.
— specular paths · biased
Soloist
VCM · vertex connection & merging
Bidirectional path tracing plus photon merging in one estimator. The integrator that handles every Heckbert-class path. The flagship.
— omnia · the union
Viola
Metropolis · MLT
Mutation in path space. Once a hard path is found, perturb it instead of starting over. Reaches the unreachable; convergence is uneven.
— pathological · sparse
Concertmaster
Hybrid · BIDIR + photon
The pragmatic mix. BiDir for diffuse, photon map for caustics, blended at the gather pass. The everyday production setting.
— pragmatic · default
Imprint & Provenance colophon — open-source
Authorship
LuxRender community
fork of PBRT 1.0 · 2008
rewritten as LuxCoreRender · 2017
luxcorerender.org
Engine
OpenCL + CPU · GPLv3
Spectral · unbiased · BiDir-first
BSDF · OSL · Disney BRDF
scenes: pbrt-compatible / lxs
Native To
Blender via BlendLuxCore
Standalone (luxcorerender)
3ds Max via plugin
~10 GB benchmark suite

— Lineage —

2008LuxRender forks PBRT 1.0. Adds OpenCL backend, BiDir, MLT.
20101.0 release. BlendLuxCore brings a Blender renderer alternative to Cycles.
2014Vertex Connection & Merging (VCM) integrator added — the soloist arrives.
2017LuxCoreRender — major rewrite. Code reorganized; core split into engine + UI layers.
2019OptiX backend explored. Spectral rendering becomes default.
20222.6 release. Path-guiding integrator added. Disney BRDF native.
∞The open integrator. Pick your light transport.

every path, joined.

One score. Six instruments. The light transport ensemble.

— § I · Authoring · Renderers / Open-Source —
Plate XXXIV · MMXXVI
projectlavos-bauhaus · 034