From 8f6faf4e8a30b82bc35d245cdc04566c58936122 Mon Sep 17 00:00:00 2001
From: Matt Pharr <matt@pharr.org>
Date: Thu, 27 Aug 2020 16:20:10 -0700
Subject: [PATCH] Add TODO about RR for media

---
 src/pbrt/gpu/media.cpp | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/pbrt/gpu/media.cpp b/src/pbrt/gpu/media.cpp
index 4012a40..6c57067 100644
--- a/src/pbrt/gpu/media.cpp
+++ b/src/pbrt/gpu/media.cpp
@@ -288,6 +288,9 @@ void GPUPathIntegrator::SampleMediumInteraction(int depth) {
             SampledSpectrum pdfNEE = ms.pdfUni;
 
             // Russian roulette
+            // TODO: should we even bother? Generally beta/pdfUni is one here,
+            // due to the way scattering events are scattered and because we're
+            // sampling exactly from the phase function's distribution...
             SampledSpectrum rrBeta = beta * ms.etaScale / pdfUni.Average();
             if (rrBeta.MaxComponentValue() < 1 && depth > 1) {
                 Float q = std::max<Float>(0, 1 - rrBeta.MaxComponentValue());
-- 
GitLab