From 52d5760be17235a1811e9a26ce849c4a33afad72 Mon Sep 17 00:00:00 2001
From: Alexander Harkness <me@bearbin.net>
Date: Mon, 30 Mar 2020 18:23:25 +0100
Subject: Add helper functions to get combined light from cChunk

These are now used for plant growth
---
 src/Blocks/BlockGrass.h |  6 ++----
 src/Blocks/BlockPlant.h | 17 +++++------------
 src/Chunk.h             |  6 ++++++
 src/Mobs/Spider.cpp     |  2 +-
 4 files changed, 14 insertions(+), 17 deletions(-)

diff --git a/src/Blocks/BlockGrass.h b/src/Blocks/BlockGrass.h
index 0e54cb092..341a44b07 100644
--- a/src/Blocks/BlockGrass.h
+++ b/src/Blocks/BlockGrass.h
@@ -60,9 +60,8 @@ public:
 				return;
 			}
 
-			NIBBLETYPE light = std::max(a_Chunk.GetBlockLight(a_RelX, a_RelY + 1, a_RelZ), a_Chunk.GetTimeAlteredLight(a_Chunk.GetSkyLight(a_RelX, a_RelY + 1, a_RelZ)));
 			// Source block is not bright enough to spread
-			if (light < 9)
+			if (a_Chunk.GetLightAltered(Vector3i(a_RelX, a_RelY + 1, a_RelZ)) < 9)
 			{
 				return;
 			}
@@ -99,8 +98,7 @@ public:
 			}
 			auto abovePos = pos.addedY(1);
 			BLOCKTYPE above = chunk->GetBlock(abovePos);
-			NIBBLETYPE light = std::max(chunk->GetBlockLight(abovePos), chunk->GetTimeAlteredLight(chunk->GetSkyLight(abovePos)));
-			if ((light > 4)  &&
+			if ((a_Chunk.GetLightAltered(abovePos) > 4)  &&
 				cBlockInfo::IsTransparent(above) &&
 				(!IsBlockLava(above)) &&
 				(!IsBlockWaterOrIce(above))
diff --git a/src/Blocks/BlockPlant.h b/src/Blocks/BlockPlant.h
index 0e249bbde..d71614cdb 100644
--- a/src/Blocks/BlockPlant.h
+++ b/src/Blocks/BlockPlant.h
@@ -77,26 +77,19 @@ protected:
 		{
 			return paGrowth;
 		}
-		NIBBLETYPE Blocklight = a_Chunk.GetBlockLight(a_RelPos);
-		NIBBLETYPE SkyLight   = a_Chunk.GetSkyLight  (a_RelPos);
-		NIBBLETYPE Light = a_Chunk.GetTimeAlteredLight(SkyLight);
-
-		// If the amount of light provided by blocks is greater than the sky light, use it instead
-		if (Blocklight > Light)
-		{
-			Light = Blocklight;
-		}
 
 		// Based on light levels, decide between growth, stay and death:
-		if (Light > 8)
+		// Grow if the combined adjusted light above is bright enough.
+		if (a_Chunk.GetLightAltered(a_RelPos + Vector3i(0, 1, 0)) > 8)
 		{
 			return paGrowth;
 		}
-		else if ((Blocklight < 9) && (SkyLight < 9))
+		// Die if the combined non-adjusted light inside is dark enough.
+		if (a_Chunk.GetLight(a_RelPos) < 8)
 		{
 			return paDeath;
 		}
-
+		// Otherwise stay the same.
 		return paStay;
 	}
 
diff --git a/src/Chunk.h b/src/Chunk.h
index dd21d0e8f..35c4acf8d 100644
--- a/src/Chunk.h
+++ b/src/Chunk.h
@@ -415,6 +415,12 @@ public:
 	/** Light alterations based on time */
 	NIBBLETYPE GetTimeAlteredLight(NIBBLETYPE a_Skylight) const;
 
+	/** Get the maximum of natural and artificial light illuminating the block (0 - 15). */
+	inline NIBBLETYPE GetLight(Vector3i a_RelPos) const { return std::max(GetBlockLight(a_RelPos), GetSkyLight(a_RelPos)); }
+
+	/** Get the maximum of natural and artificial light illuminating the block (0 - 15), taking daytime into account. */
+	inline NIBBLETYPE GetLightAltered(Vector3i a_RelPos) const { return std::max(GetBlockLight(a_RelPos), GetSkyLightAltered(a_RelPos)); }
+
 	/** Get the level of artificial light illuminating the block (0 - 15) */
 	inline NIBBLETYPE GetBlockLight(Vector3i a_RelPos) const { return m_ChunkData.GetBlockLight(a_RelPos); }
 	inline NIBBLETYPE GetBlockLight(int a_RelX, int a_RelY, int a_RelZ) const { return m_ChunkData.GetBlockLight({ a_RelX, a_RelY, a_RelZ }); }
diff --git a/src/Mobs/Spider.cpp b/src/Mobs/Spider.cpp
index 329d89e93..319610fa4 100644
--- a/src/Mobs/Spider.cpp
+++ b/src/Mobs/Spider.cpp
@@ -50,7 +50,7 @@ void cSpider::EventSeePlayer(cPlayer * a_Player, cChunk & a_Chunk)
 
 	if (
 		a_Player->CanMobsTarget() &&
-		!((Chunk->GetSkyLightAltered(Rel.x, Rel.y, Rel.z) > 11) || (Chunk->GetBlockLight(Rel.x, Rel.y, Rel.z) > 11))
+		!(Chunk->GetLightAltered(Rel) > 11)
 	)
 	{
 		super::EventSeePlayer(a_Player, a_Chunk);
-- 
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