From 11aab4198be1a0f1104a433896e908e4c86de0c9 Mon Sep 17 00:00:00 2001
From: Jude Melton-Houghton <jwmhjwmh@gmail.com>
Date: Tue, 29 Mar 2022 12:06:44 -0400
Subject: Optimize swapping nodes with equivalent lighting

---
 src/map.cpp | 65 ++++++++++++++++++++++++++++++++++++++++++-------------------
 1 file changed, 45 insertions(+), 20 deletions(-)

(limited to 'src/map.cpp')

diff --git a/src/map.cpp b/src/map.cpp
index a11bbb96a..1cbc55707 100644
--- a/src/map.cpp
+++ b/src/map.cpp
@@ -165,24 +165,32 @@ MapNode Map::getNode(v3s16 p, bool *is_valid_position)
 	return node;
 }
 
-// throws InvalidPositionException if not found
-void Map::setNode(v3s16 p, MapNode & n)
+static void set_node_in_block(MapBlock *block, v3s16 relpos, MapNode n)
 {
-	v3s16 blockpos = getNodeBlockPos(p);
-	MapBlock *block = getBlockNoCreate(blockpos);
-	v3s16 relpos = p - blockpos*MAP_BLOCKSIZE;
 	// Never allow placing CONTENT_IGNORE, it causes problems
 	if(n.getContent() == CONTENT_IGNORE){
+		const NodeDefManager *nodedef = block->getParent()->getNodeDefManager();
+		v3s16 blockpos = block->getPos();
+		v3s16 p = blockpos * MAP_BLOCKSIZE + relpos;
 		bool temp_bool;
-		errorstream<<"Map::setNode(): Not allowing to place CONTENT_IGNORE"
+		errorstream<<"Not allowing to place CONTENT_IGNORE"
 				<<" while trying to replace \""
-				<<m_nodedef->get(block->getNodeNoCheck(relpos, &temp_bool)).name
+				<<nodedef->get(block->getNodeNoCheck(relpos, &temp_bool)).name
 				<<"\" at "<<PP(p)<<" (block "<<PP(blockpos)<<")"<<std::endl;
 		return;
 	}
 	block->setNodeNoCheck(relpos, n);
 }
 
+// throws InvalidPositionException if not found
+void Map::setNode(v3s16 p, MapNode & n)
+{
+	v3s16 blockpos = getNodeBlockPos(p);
+	MapBlock *block = getBlockNoCreate(blockpos);
+	v3s16 relpos = p - blockpos*MAP_BLOCKSIZE;
+	set_node_in_block(block, relpos, n);
+}
+
 void Map::addNodeAndUpdate(v3s16 p, MapNode n,
 		std::map<v3s16, MapBlock*> &modified_blocks,
 		bool remove_metadata)
@@ -190,8 +198,14 @@ void Map::addNodeAndUpdate(v3s16 p, MapNode n,
 	// Collect old node for rollback
 	RollbackNode rollback_oldnode(this, p, m_gamedef);
 
+	v3s16 blockpos = getNodeBlockPos(p);
+	MapBlock *block = getBlockNoCreate(blockpos);
+	if (block->isDummy())
+		throw InvalidPositionException();
+	v3s16 relpos = p - blockpos * MAP_BLOCKSIZE;
+
 	// This is needed for updating the lighting
-	MapNode oldnode = getNode(p);
+	MapNode oldnode = block->getNodeUnsafe(relpos);
 
 	// Remove node metadata
 	if (remove_metadata) {
@@ -199,18 +213,29 @@ void Map::addNodeAndUpdate(v3s16 p, MapNode n,
 	}
 
 	// Set the node on the map
-	// Ignore light (because calling voxalgo::update_lighting_nodes)
-	n.setLight(LIGHTBANK_DAY, 0, m_nodedef);
-	n.setLight(LIGHTBANK_NIGHT, 0, m_nodedef);
-	setNode(p, n);
-
-	// Update lighting
-	std::vector<std::pair<v3s16, MapNode> > oldnodes;
-	oldnodes.emplace_back(p, oldnode);
-	voxalgo::update_lighting_nodes(this, oldnodes, modified_blocks);
-
-	for (auto &modified_block : modified_blocks) {
-		modified_block.second->expireDayNightDiff();
+	const ContentFeatures &cf = m_nodedef->get(n);
+	const ContentFeatures &oldcf = m_nodedef->get(oldnode);
+	if (cf.lightingEquivalent(oldcf)) {
+		// No light update needed, just copy over the old light.
+		n.setLight(LIGHTBANK_DAY, oldnode.getLightRaw(LIGHTBANK_DAY, oldcf), cf);
+		n.setLight(LIGHTBANK_NIGHT, oldnode.getLightRaw(LIGHTBANK_NIGHT, oldcf), cf);
+		set_node_in_block(block, relpos, n);
+
+		modified_blocks[blockpos] = block;
+	} else {
+		// Ignore light (because calling voxalgo::update_lighting_nodes)
+		n.setLight(LIGHTBANK_DAY, 0, cf);
+		n.setLight(LIGHTBANK_NIGHT, 0, cf);
+		set_node_in_block(block, relpos, n);
+
+		// Update lighting
+		std::vector<std::pair<v3s16, MapNode> > oldnodes;
+		oldnodes.emplace_back(p, oldnode);
+		voxalgo::update_lighting_nodes(this, oldnodes, modified_blocks);
+
+		for (auto &modified_block : modified_blocks) {
+			modified_block.second->expireDayNightDiff();
+		}
 	}
 
 	// Report for rollback
-- 
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