From 999faa9d90453435ab1c61935a448fef01ff29e7 Mon Sep 17 00:00:00 2001
From: peterbell10 <peterbell10@live.co.uk>
Date: Wed, 21 Feb 2018 10:30:48 +0000
Subject: cLightingThread: Faster chunk reading (#4185)

Profiled at a 10x speedup for cLightingThread::ReadChunks.
---
 src/LightingThread.cpp | 35 +++++++++++++++++++++++------------
 1 file changed, 23 insertions(+), 12 deletions(-)

(limited to 'src/LightingThread.cpp')

diff --git a/src/LightingThread.cpp b/src/LightingThread.cpp
index 39b22f748..ccefdfef2 100644
--- a/src/LightingThread.cpp
+++ b/src/LightingThread.cpp
@@ -20,21 +20,31 @@ class cReader :
 	virtual void ChunkData(const cChunkData & a_ChunkBuffer) override
 	{
 		BLOCKTYPE * OutputRows = m_BlockTypes;
-		int InputIdx = 0;
 		int OutputIdx = m_ReadingChunkX + m_ReadingChunkZ * cChunkDef::Width * 3;
-		int MaxHeight = std::min(+cChunkDef::Height, m_MaxHeight + 16);  // Need 16 blocks above the highest
-		for (int y = 0; y < MaxHeight; y++)
+		for (size_t i = 0; i != cChunkData::NumSections; ++i)
 		{
-			for (int z = 0; z < cChunkDef::Width; z++)
+			auto * Section = a_ChunkBuffer.GetSection(i);
+			if (Section == nullptr)
+			{
+				// Skip to the next section
+				OutputIdx += 9 * cChunkData::SectionHeight * cChunkDef::Width;
+				continue;
+			}
+
+			for (size_t OffsetY = 0; OffsetY != cChunkData::SectionHeight; ++OffsetY)
 			{
-				a_ChunkBuffer.CopyBlockTypes(OutputRows + OutputIdx * 16, static_cast<size_t>(InputIdx * 16), 16);
-				InputIdx++;
-				OutputIdx += 3;
-			}  // for z
-			// Skip into the next y-level in the 3x3 chunk blob; each level has cChunkDef::Width * 9 rows
-			// We've already walked cChunkDef::Width * 3 in the "for z" cycle, that makes cChunkDef::Width * 6 rows left to skip
-			OutputIdx += cChunkDef::Width * 6;
-		}  // for y
+				for (size_t Z = 0; Z != cChunkDef::Width; ++Z)
+				{
+					auto InPtr = Section->m_BlockTypes + Z * cChunkDef::Width + OffsetY * cChunkDef::Width * cChunkDef::Width;
+					std::copy_n(InPtr, cChunkDef::Width, OutputRows + OutputIdx * cChunkDef::Width);
+
+					OutputIdx += 3;
+				}
+				// Skip into the next y-level in the 3x3 chunk blob; each level has cChunkDef::Width * 9 rows
+				// We've already walked cChunkDef::Width * 3 in the "for z" cycle, that makes cChunkDef::Width * 6 rows left to skip
+				OutputIdx += cChunkDef::Width * 6;
+			}
+		}
 	}  // BlockTypes()
 
 
@@ -78,6 +88,7 @@ public:
 		m_BlockTypes(a_BlockTypes),
 		m_HeightMap(a_HeightMap)
 	{
+		std::fill_n(m_BlockTypes, cChunkDef::NumBlocks * 9, E_BLOCK_AIR);
 	}
 } ;
 
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