From ccf72ac9ce8bf689736671ac4a2158a519dee85a Mon Sep 17 00:00:00 2001
From: Coolthulhu <Coolthulhu@gmail.com>
Date: Fri, 1 Jan 2016 21:01:57 +0100
Subject: [PATCH] Tiny comment

---
 src/lightmap.cpp | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/lightmap.cpp b/src/lightmap.cpp
index 16eabf670ede4..6b1994277c1ee 100644
--- a/src/lightmap.cpp
+++ b/src/lightmap.cpp
@@ -589,6 +589,8 @@ void cast_zlight(
                 if( check( current_transparency, last_intensity ) ) {
                     float next_cumulative_transparency =
                         ((distance - 1) * cumulative_transparency + current_transparency) / distance;
+                    // Blocks can be merged if they are actually a single rectangle
+                    // rather than rectangle + line shorter than rectangle's width
                     const bool merge_blocks = end_minor <= trailing_edge_minor;
                     // trailing_edge_major can be less than start_major
                     const float trailing_clipped = std::max( trailing_edge_major, start_major );