map.cpp

		// to 0.
		// This also collects the nodes at the border which will spread
		// light again into this.
		unLightNeighbors(bank, p, lightwas, light_sources, modified_blocks);

		n.setLight(bank, 0, ndef);
	}

	/*
		If node lets sunlight through and is under sunlight, it has
		sunlight too.
	*/
	if(node_under_sunlight && ndef->get(n).sunlight_propagates)
	{
		n.setLight(LIGHTBANK_DAY, LIGHT_SUN, ndef);
	}

	/*
		Remove node metadata
	*/

	removeNodeMetadata(p);

	/*
		Set the node on the map
	*/

	setNode(p, n);

	/*
		If node is under sunlight and doesn't let sunlight through,
		take all sunlighted nodes under it and clear light from them
		and from where the light has been spread.
		TODO: This could be optimized by mass-unlighting instead
			  of looping
	*/
	if(node_under_sunlight && !ndef->get(n).sunlight_propagates)
	{
		s16 y = p.Y - 1;
		for(;; y--){
			//m_dout<<DTIME<<"y="<<y<<std::endl;
			v3s16 n2pos(p.X, y, p.Z);

			MapNode n2;
			try{
				n2 = getNode(n2pos);
			}
			catch(InvalidPositionException &e)
			{
				break;
			}

			if(n2.getLight(LIGHTBANK_DAY, ndef) == LIGHT_SUN)
			{
				unLightNeighbors(LIGHTBANK_DAY,
						n2pos, n2.getLight(LIGHTBANK_DAY, ndef),
						light_sources, modified_blocks);
				n2.setLight(LIGHTBANK_DAY, 0, ndef);
				setNode(n2pos, n2);
			}
			else
				break;
		}
	}

	for(s32 i=0; i<2; i++)
	{
		enum LightBank bank = banks[i];

		/*
			Spread light from all nodes that might be capable of doing so
		*/
		spreadLight(bank, light_sources, modified_blocks);
	}

	/*
		Update information about whether day and night light differ
	*/
	for(std::map<v3s16, MapBlock*>::iterator
			i = modified_blocks.begin();
			i != modified_blocks.end(); ++i)
	{
		i->second->expireDayNightDiff();
	}

	/*
		Report for rollback
	*/
	if(m_gamedef->rollback())
	{
		RollbackNode rollback_newnode(this, p, m_gamedef);
		RollbackAction action;
		action.setSetNode(p, rollback_oldnode, rollback_newnode);
		m_gamedef->rollback()->reportAction(action);
	}

	/*
		Add neighboring liquid nodes and the node itself if it is
		liquid (=water node was added) to transform queue.
		note: todo: for liquid_finite enough to add only self node
	*/
	v3s16 dirs[7] = {
		v3s16(0,0,0), // self
		v3s16(0,0,1), // back
		v3s16(0,1,0), // top
		v3s16(1,0,0), // right
		v3s16(0,0,-1), // front
		v3s16(0,-1,0), // bottom
		v3s16(-1,0,0), // left
	};
	for(u16 i=0; i<7; i++)
	{
		try
		{

		v3s16 p2 = p + dirs[i];

		MapNode n2 = getNode(p2);
		if(ndef->get(n2).isLiquid() || n2.getContent() == CONTENT_AIR)
		{
			m_transforming_liquid.push_back(p2);
		}

		}catch(InvalidPositionException &e)
		{
		}
	}
}

/*
*/
void Map::removeNodeAndUpdate(v3s16 p,
		std::map<v3s16, MapBlock*> &modified_blocks)
{
	INodeDefManager *ndef = m_gamedef->ndef();

	/*PrintInfo(m_dout);
	m_dout<<DTIME<<"Map::removeNodeAndUpdate(): p=("
			<<p.X<<","<<p.Y<<","<<p.Z<<")"<<std::endl;*/

	bool node_under_sunlight = true;

	v3s16 toppos = p + v3s16(0,1,0);

	// Node will be replaced with this
	content_t replace_material = CONTENT_AIR;

	/*
		Collect old node for rollback
	*/
	RollbackNode rollback_oldnode(this, p, m_gamedef);

	/*
		If there is a node at top and it doesn't have sunlight,
		there will be no sunlight going down.
	*/
	try{
		MapNode topnode = getNode(toppos);

		if(topnode.getLight(LIGHTBANK_DAY, ndef) != LIGHT_SUN)
			node_under_sunlight = false;
	}
	catch(InvalidPositionException &e)
	{
	}

	std::set<v3s16> light_sources;

	enum LightBank banks[] =
	{
		LIGHTBANK_DAY,
		LIGHTBANK_NIGHT
	};
	for(s32 i=0; i<2; i++)
	{
		enum LightBank bank = banks[i];

		/*
			Unlight neighbors (in case the node is a light source)
		*/
		unLightNeighbors(bank, p,
				getNode(p).getLight(bank, ndef),
				light_sources, modified_blocks);
	}

	/*
		Remove node metadata
	*/

	removeNodeMetadata(p);

	/*
		Remove the node.
		This also clears the lighting.
	*/

	MapNode n;
	n.setContent(replace_material);
	setNode(p, n);

	for(s32 i=0; i<2; i++)
	{
		enum LightBank bank = banks[i];

		/*
			Recalculate lighting
		*/
		spreadLight(bank, light_sources, modified_blocks);
	}

	// Add the block of the removed node to modified_blocks
	v3s16 blockpos = getNodeBlockPos(p);
	MapBlock * block = getBlockNoCreate(blockpos);
	assert(block != NULL);
	modified_blocks[blockpos] = block;

	/*
		If the removed node was under sunlight, propagate the
		sunlight down from it and then light all neighbors
		of the propagated blocks.
	*/
	if(node_under_sunlight)
	{
		s16 ybottom = propagateSunlight(p, modified_blocks);
		/*m_dout<<DTIME<<"Node was under sunlight. "
				"Propagating sunlight";
		m_dout<<DTIME<<" -> ybottom="<<ybottom<<std::endl;*/
		s16 y = p.Y;
		for(; y >= ybottom; y--)
		{
			v3s16 p2(p.X, y, p.Z);
			/*m_dout<<DTIME<<"lighting neighbors of node ("
					<<p2.X<<","<<p2.Y<<","<<p2.Z<<")"
					<<std::endl;*/
			lightNeighbors(LIGHTBANK_DAY, p2, modified_blocks);
		}
	}
	else
	{
		// Set the lighting of this node to 0
		// TODO: Is this needed? Lighting is cleared up there already.
		try{
			MapNode n = getNode(p);
			n.setLight(LIGHTBANK_DAY, 0, ndef);
			setNode(p, n);
		}
		catch(InvalidPositionException &e)
		{
			assert(0);
		}
	}

	for(s32 i=0; i<2; i++)
	{
		enum LightBank bank = banks[i];

		// Get the brightest neighbour node and propagate light from it
		v3s16 n2p = getBrightestNeighbour(bank, p);
		try{
			//MapNode n2 = getNode(n2p);
			lightNeighbors(bank, n2p, modified_blocks);
		}
		catch(InvalidPositionException &e)
		{
		}
	}

	/*
		Update information about whether day and night light differ
	*/
	for(std::map<v3s16, MapBlock*>::iterator
			i = modified_blocks.begin();
			i != modified_blocks.end(); ++i)
	{
		i->second->expireDayNightDiff();
	}

	/*
		Report for rollback
	*/
	if(m_gamedef->rollback())
	{
		RollbackNode rollback_newnode(this, p, m_gamedef);
		RollbackAction action;
		action.setSetNode(p, rollback_oldnode, rollback_newnode);
		m_gamedef->rollback()->reportAction(action);
	}

	/*
		Add neighboring liquid nodes and this node to transform queue.
		(it's vital for the node itself to get updated last.)
		note: todo: for liquid_finite enough to add only self node
	*/
	v3s16 dirs[7] = {
		v3s16(0,0,1), // back
		v3s16(0,1,0), // top
		v3s16(1,0,0), // right
		v3s16(0,0,-1), // front
		v3s16(0,-1,0), // bottom
		v3s16(-1,0,0), // left
		v3s16(0,0,0), // self
	};
	for(u16 i=0; i<7; i++)
	{
		try
		{

		v3s16 p2 = p + dirs[i];

		MapNode n2 = getNode(p2);
		if(ndef->get(n2).isLiquid() || n2.getContent() == CONTENT_AIR)
		{
			m_transforming_liquid.push_back(p2);
		}

		}catch(InvalidPositionException &e)
		{
		}
	}
}

bool Map::addNodeWithEvent(v3s16 p, MapNode n)
{
	MapEditEvent event;
	event.type = MEET_ADDNODE;
	event.p = p;
	event.n = n;

	bool succeeded = true;
	try{
		std::map<v3s16, MapBlock*> modified_blocks;
		addNodeAndUpdate(p, n, modified_blocks);

		// Copy modified_blocks to event
		for(std::map<v3s16, MapBlock*>::iterator
				i = modified_blocks.begin();
				i != modified_blocks.end(); ++i)
		{
			event.modified_blocks.insert(i->first);
		}
	}
	catch(InvalidPositionException &e){
		succeeded = false;
	}

	dispatchEvent(&event);

	return succeeded;
}

bool Map::removeNodeWithEvent(v3s16 p)
{
	MapEditEvent event;
	event.type = MEET_REMOVENODE;
	event.p = p;

	bool succeeded = true;
	try{
		std::map<v3s16, MapBlock*> modified_blocks;
		removeNodeAndUpdate(p, modified_blocks);

		// Copy modified_blocks to event
		for(std::map<v3s16, MapBlock*>::iterator
				i = modified_blocks.begin();
				i != modified_blocks.end(); ++i)
		{
			event.modified_blocks.insert(i->first);
		}
	}
	catch(InvalidPositionException &e){
		succeeded = false;
	}

	dispatchEvent(&event);

	return succeeded;
}

bool Map::getDayNightDiff(v3s16 blockpos)
{
	try{
		v3s16 p = blockpos + v3s16(0,0,0);
		MapBlock *b = getBlockNoCreate(p);
		if(b->getDayNightDiff())
			return true;
	}
	catch(InvalidPositionException &e){}
	// Leading edges
	try{
		v3s16 p = blockpos + v3s16(-1,0,0);
		MapBlock *b = getBlockNoCreate(p);
		if(b->getDayNightDiff())
			return true;
	}
	catch(InvalidPositionException &e){}
	try{
		v3s16 p = blockpos + v3s16(0,-1,0);
		MapBlock *b = getBlockNoCreate(p);
		if(b->getDayNightDiff())
			return true;
	}
	catch(InvalidPositionException &e){}
	try{
		v3s16 p = blockpos + v3s16(0,0,-1);
		MapBlock *b = getBlockNoCreate(p);
		if(b->getDayNightDiff())
			return true;
	}
	catch(InvalidPositionException &e){}
	// Trailing edges
	try{
		v3s16 p = blockpos + v3s16(1,0,0);
		MapBlock *b = getBlockNoCreate(p);
		if(b->getDayNightDiff())
			return true;
	}
	catch(InvalidPositionException &e){}
	try{
		v3s16 p = blockpos + v3s16(0,1,0);
		MapBlock *b = getBlockNoCreate(p);
		if(b->getDayNightDiff())
			return true;
	}
	catch(InvalidPositionException &e){}
	try{
		v3s16 p = blockpos + v3s16(0,0,1);
		MapBlock *b = getBlockNoCreate(p);
		if(b->getDayNightDiff())
			return true;
	}
	catch(InvalidPositionException &e){}

	return false;
}

/*
	Updates usage timers
*/
void Map::timerUpdate(float dtime, float unload_timeout,
		std::list<v3s16> *unloaded_blocks)
{
	bool save_before_unloading = (mapType() == MAPTYPE_SERVER);

	// Profile modified reasons
	Profiler modprofiler;

	std::list<v2s16> sector_deletion_queue;
	u32 deleted_blocks_count = 0;
	u32 saved_blocks_count = 0;
	u32 block_count_all = 0;

	beginSave();
	for(std::map<v2s16, MapSector*>::iterator si = m_sectors.begin();
		si != m_sectors.end(); ++si)
	{
		MapSector *sector = si->second;

		bool all_blocks_deleted = true;

		std::list<MapBlock*> blocks;
		sector->getBlocks(blocks);

		for(std::list<MapBlock*>::iterator i = blocks.begin();
				i != blocks.end(); ++i)
		{
			MapBlock *block = (*i);

			block->incrementUsageTimer(dtime);

			if(block->refGet() == 0 && block->getUsageTimer() > unload_timeout)
			{
				v3s16 p = block->getPos();

				// Save if modified
				if(block->getModified() != MOD_STATE_CLEAN
						&& save_before_unloading)
				{
					modprofiler.add(block->getModifiedReason(), 1);
					saveBlock(block);
					saved_blocks_count++;
				}

				// Delete from memory
				sector->deleteBlock(block);

				if(unloaded_blocks)
					unloaded_blocks->push_back(p);

				deleted_blocks_count++;
			}
			else
			{
				all_blocks_deleted = false;
				block_count_all++;
			}
		}

		if(all_blocks_deleted)
		{
			sector_deletion_queue.push_back(si->first);
		}
	}
	endSave();

	// Finally delete the empty sectors
	deleteSectors(sector_deletion_queue);

	if(deleted_blocks_count != 0)
	{
		PrintInfo(infostream); // ServerMap/ClientMap:
		infostream<<"Unloaded "<<deleted_blocks_count
				<<" blocks from memory";
		if(save_before_unloading)
			infostream<<", of which "<<saved_blocks_count<<" were written";
		infostream<<", "<<block_count_all<<" blocks in memory";
		infostream<<"."<<std::endl;
		if(saved_blocks_count != 0){
			PrintInfo(infostream); // ServerMap/ClientMap:
			infostream<<"Blocks modified by: "<<std::endl;
			modprofiler.print(infostream);
		}
	}
}

void Map::unloadUnreferencedBlocks(std::list<v3s16> *unloaded_blocks)
{
	timerUpdate(0.0, -1.0, unloaded_blocks);
}

void Map::deleteSectors(std::list<v2s16> &list)
{
	for(std::list<v2s16>::iterator j = list.begin();
		j != list.end(); ++j)
	{
		MapSector *sector = m_sectors[*j];
		// If sector is in sector cache, remove it from there
		if(m_sector_cache == sector)
			m_sector_cache = NULL;
		// Remove from map and delete
		m_sectors.erase(*j);
		delete sector;
	}
}

#if 0
void Map::unloadUnusedData(float timeout,
		core::list<v3s16> *deleted_blocks)
{
	core::list<v2s16> sector_deletion_queue;
	u32 deleted_blocks_count = 0;
	u32 saved_blocks_count = 0;

	core::map<v2s16, MapSector*>::Iterator si = m_sectors.getIterator();
	for(; si.atEnd() == false; si++)
	{
		MapSector *sector = si.getNode()->getValue();

		bool all_blocks_deleted = true;

		core::list<MapBlock*> blocks;
		sector->getBlocks(blocks);
		for(core::list<MapBlock*>::Iterator i = blocks.begin();
				i != blocks.end(); i++)
		{
			MapBlock *block = (*i);

			if(block->getUsageTimer() > timeout)
			{
				// Save if modified
				if(block->getModified() != MOD_STATE_CLEAN)
				{
					saveBlock(block);
					saved_blocks_count++;
				}
				// Delete from memory
				sector->deleteBlock(block);
				deleted_blocks_count++;
			}
			else
			{
				all_blocks_deleted = false;
			}
		}

		if(all_blocks_deleted)
		{
			sector_deletion_queue.push_back(si.getNode()->getKey());
		}
	}

	deleteSectors(sector_deletion_queue);

	infostream<<"Map: Unloaded "<<deleted_blocks_count<<" blocks from memory"
			<<", of which "<<saved_blocks_count<<" were wr."
			<<std::endl;

	//return sector_deletion_queue.getSize();
	//return deleted_blocks_count;
}
#endif

void Map::PrintInfo(std::ostream &out)
{
	out<<"Map: ";
}

#define WATER_DROP_BOOST 4

enum NeighborType {
	NEIGHBOR_UPPER,
	NEIGHBOR_SAME_LEVEL,
	NEIGHBOR_LOWER
};
struct NodeNeighbor {
	MapNode n;
	NeighborType t;
	v3s16 p;
	bool l; //can liquid
	bool i; //infinity
};

void Map::transforming_liquid_add(v3s16 p) {
        m_transforming_liquid.push_back(p);
}

s32 Map::transforming_liquid_size() {
        return m_transforming_liquid.size();
}

const v3s16 g_7dirs[7] =
{
	// +right, +top, +back
	v3s16( 0,-1, 0), // bottom
	v3s16( 0, 0, 0), // self
	v3s16( 0, 0, 1), // back
	v3s16( 0, 0,-1), // front
	v3s16( 1, 0, 0), // right
	v3s16(-1, 0, 0), // left
	v3s16( 0, 1, 0)  // top
};

#define D_BOTTOM 0
#define D_TOP 6
#define D_SELF 1

void Map::transformLiquidsFinite(std::map<v3s16, MapBlock*> & modified_blocks)
{
	INodeDefManager *nodemgr = m_gamedef->ndef();

	DSTACK(__FUNCTION_NAME);
	//TimeTaker timer("transformLiquids()");

	u32 loopcount = 0;
	u32 initial_size = m_transforming_liquid.size();

	u8 relax = g_settings->getS16("liquid_relax");
	bool fast_flood = g_settings->getS16("liquid_fast_flood");
	int water_level = g_settings->getS16("water_level");

	// list of nodes that due to viscosity have not reached their max level height
	UniqueQueue<v3s16> must_reflow, must_reflow_second;

	// List of MapBlocks that will require a lighting update (due to lava)
	std::map<v3s16, MapBlock*> lighting_modified_blocks;

	u16 loop_max = g_settings->getU16("liquid_loop_max");

	//if (m_transforming_liquid.size() > 0) errorstream << "Liquid queue size="<<m_transforming_liquid.size()<<std::endl;

	while (m_transforming_liquid.size() > 0)
	{
		// This should be done here so that it is done when continue is used
		if (loopcount >= initial_size || loopcount >= loop_max)
			break;
		loopcount++;
		/*
			Get a queued transforming liquid node
		*/
		v3s16 p0 = m_transforming_liquid.pop_front();
		u16 total_level = 0;
		// surrounding flowing liquid nodes
		NodeNeighbor neighbors[7]; 
		// current level of every block
		s8 liquid_levels[7] = {-1, -1, -1, -1, -1, -1, -1};
		 // target levels
		s8 liquid_levels_want[7] = {-1, -1, -1, -1, -1, -1, -1};
		s8 can_liquid_same_level = 0;
		content_t liquid_kind = CONTENT_IGNORE;
		content_t liquid_kind_flowing = CONTENT_IGNORE;
		/*
			Collect information about the environment
		 */
		const v3s16 *dirs = g_7dirs;
		for (u16 i = 0; i < 7; i++) {
			NeighborType nt = NEIGHBOR_SAME_LEVEL;
			switch (i) {
				case D_TOP:
					nt = NEIGHBOR_UPPER;
					break;
				case D_BOTTOM:
					nt = NEIGHBOR_LOWER;
					break;
			}
			v3s16 npos = p0 + dirs[i];

			neighbors[i].n = getNodeNoEx(npos);
			neighbors[i].t = nt;
			neighbors[i].p = npos;
			neighbors[i].l = 0;
			neighbors[i].i = 0;
			NodeNeighbor & nb = neighbors[i];

			switch (nodemgr->get(nb.n.getContent()).liquid_type) {
				case LIQUID_NONE:
					if (nb.n.getContent() == CONTENT_AIR) {
						liquid_levels[i] = 0;
						nb.l = 1;
					}
					break;
				case LIQUID_SOURCE:
					// if this node is not (yet) of a liquid type,
					// choose the first liquid type we encounter
					if (liquid_kind_flowing == CONTENT_IGNORE)
						liquid_kind_flowing = nodemgr->getId(
							nodemgr->get(nb.n).liquid_alternative_flowing);
					if (liquid_kind == CONTENT_IGNORE)
						liquid_kind = nb.n.getContent();
					if (nb.n.getContent() == liquid_kind) {
						liquid_levels[i] = nb.n.getLevel(nodemgr); //LIQUID_LEVEL_SOURCE;
						nb.l = 1;
						nb.i = (nb.n.param2 & LIQUID_INFINITY_MASK);
					}
					break;
				case LIQUID_FLOWING:
					// if this node is not (yet) of a liquid type,
					// choose the first liquid type we encounter
					if (liquid_kind_flowing == CONTENT_IGNORE)
						liquid_kind_flowing = nb.n.getContent();
					if (liquid_kind == CONTENT_IGNORE)
						liquid_kind = nodemgr->getId(
							nodemgr->get(nb.n).liquid_alternative_source);
					if (nb.n.getContent() == liquid_kind_flowing) {
						liquid_levels[i] = nb.n.getLevel(nodemgr); //(nb.n.param2 & LIQUID_LEVEL_MASK);
						nb.l = 1;
					}
					break;
			}
			
			if (nb.l && nb.t == NEIGHBOR_SAME_LEVEL)
				++can_liquid_same_level;
			if (liquid_levels[i] > 0)
				total_level += liquid_levels[i];

			/*
			infostream << "get node i=" <<(int)i<<" " << PP(npos) << " c="
			<< nb.n.getContent() <<" p0="<< (int)nb.n.param0 <<" p1="
			<< (int)nb.n.param1 <<" p2="<< (int)nb.n.param2 << " lt="
			<< nodemgr->get(nb.n.getContent()).liquid_type
			//<< " lk=" << liquid_kind << " lkf=" << liquid_kind_flowing
			<< " l="<< nb.l	<< " inf="<< nb.i << " nlevel=" << (int)liquid_levels[i]
			<< " tlevel=" << (int)total_level << " cansame="
			<< (int)can_liquid_same_level << std::endl;
			*/
		}

		if (liquid_kind == CONTENT_IGNORE ||
			!neighbors[D_SELF].l ||
			total_level <= 0)
			continue;

		// fill bottom block
		if (neighbors[D_BOTTOM].l) {
			liquid_levels_want[D_BOTTOM] = total_level > LIQUID_LEVEL_SOURCE ?
				LIQUID_LEVEL_SOURCE : total_level;
			total_level -= liquid_levels_want[D_BOTTOM];
		}

		//relax up
		if (relax && ((p0.Y == water_level) || (fast_flood && p0.Y <= water_level)) && liquid_levels[D_TOP] == 0 &&
			liquid_levels[D_BOTTOM] == LIQUID_LEVEL_SOURCE &&
			total_level >= LIQUID_LEVEL_SOURCE * can_liquid_same_level-
			(can_liquid_same_level - relax) &&
			can_liquid_same_level >= relax + 1) { 
			total_level = LIQUID_LEVEL_SOURCE * can_liquid_same_level; 
		}

		// prevent lakes in air above unloaded blocks
		if (liquid_levels[D_TOP] == 0 && (p0.Y > water_level) && neighbors[D_BOTTOM].n.getContent() == CONTENT_IGNORE && !(loopcount % 3)) {
			--total_level;
		}

		// calculate self level 5 blocks
		u8 want_level = 
			  total_level >= LIQUID_LEVEL_SOURCE * can_liquid_same_level
			? LIQUID_LEVEL_SOURCE 
			: total_level / can_liquid_same_level;
		total_level -= want_level * can_liquid_same_level;

		//relax down
		if (relax && p0.Y == water_level + 1 && liquid_levels[D_TOP] == 0 &&
			liquid_levels[D_BOTTOM] == LIQUID_LEVEL_SOURCE && want_level == 0 &&
			total_level <= (can_liquid_same_level - relax) &&
			can_liquid_same_level >= relax + 1) {
			total_level = 0;
		}

		for (u16 ii = D_SELF; ii < D_TOP; ++ii) { // fill only same level
			if (!neighbors[ii].l)
				continue;
			liquid_levels_want[ii] = want_level;
			if (liquid_levels_want[ii] < LIQUID_LEVEL_SOURCE && total_level > 0) {
				if (loopcount % 3 || liquid_levels[ii] <= 0){
					if (liquid_levels[ii] > liquid_levels_want[ii]) {
						++liquid_levels_want[ii];
						--total_level;
					}
				} else if (neighbors[ii].l > 0){
						++liquid_levels_want[ii];
						--total_level;
				}
			}
		}

		for (u16 ii = 0; ii < 7; ++ii) {
			if (total_level < 1) break;
			if (liquid_levels_want[ii] >= 0 &&
				liquid_levels_want[ii] < LIQUID_LEVEL_SOURCE) {
				++liquid_levels_want[ii];
				--total_level;
			}
		}

		// fill top block if can
		if (neighbors[D_TOP].l) {
			liquid_levels_want[D_TOP] = total_level > LIQUID_LEVEL_SOURCE ?
				LIQUID_LEVEL_SOURCE : total_level;
			total_level -= liquid_levels_want[D_TOP];
		}

		for (u16 ii = 0; ii < 7; ii++) // infinity and cave flood optimization
			if (    neighbors[ii].i ||
				(liquid_levels_want[ii] >= 0 &&
				 (fast_flood && p0.Y < water_level &&
				  (initial_size >= 1000
				   && ii != D_TOP
				   && want_level >= LIQUID_LEVEL_SOURCE/4
				   && can_liquid_same_level >= 5
				   && liquid_levels[D_TOP] >= LIQUID_LEVEL_SOURCE))))
				liquid_levels_want[ii] = LIQUID_LEVEL_SOURCE;

		/*
		if (total_level > 0) //|| flowed != volume)
			infostream <<" AFTER level=" << (int)total_level 
			//<< " flowed="<<flowed<< " volume=" << volume
			<< " wantsame="<<(int)want_level<< " top="
			<< (int)liquid_levels_want[D_TOP]<< " topwas="
			<< (int)liquid_levels[D_TOP]<< " bot="
			<< (int)liquid_levels_want[D_BOTTOM]<<std::endl;
		*/

		//u8 changed = 0;
		for (u16 i = 0; i < 7; i++) {
			if (liquid_levels_want[i] < 0 || !neighbors[i].l) 
				continue;
			MapNode & n0 = neighbors[i].n;
			p0 = neighbors[i].p;
			/*
				decide on the type (and possibly level) of the current node
			*/
			content_t new_node_content;
			s8 new_node_level = -1;
			u8 viscosity = nodemgr->get(liquid_kind).liquid_viscosity;
			if (viscosity > 1 && liquid_levels_want[i] != liquid_levels[i]) {
				// amount to gain, limited by viscosity
				// must be at least 1 in absolute value
				s8 level_inc = liquid_levels_want[i] - liquid_levels[i];
				if (level_inc < -viscosity || level_inc > viscosity)
					new_node_level = liquid_levels[i] + level_inc/viscosity;
				else if (level_inc < 0)
					new_node_level = liquid_levels[i] - 1;
				else if (level_inc > 0)
					new_node_level = liquid_levels[i] + 1;
			} else {
				new_node_level = liquid_levels_want[i];
			}
			
			if (new_node_level >= LIQUID_LEVEL_SOURCE)
				new_node_content = liquid_kind;
			else if (new_node_level > 0)
				new_node_content = liquid_kind_flowing;
			else
				new_node_content = CONTENT_AIR;
			
			// last level must flow down on stairs
			if (liquid_levels_want[i] != liquid_levels[i] &&
				liquid_levels[D_TOP] <= 0 && !neighbors[D_BOTTOM].l &&
				new_node_level >= 1 && new_node_level <= 2) {
				for (u16 ii = D_SELF + 1; ii < D_TOP; ++ii) { // only same level
					if (neighbors[ii].l)
						must_reflow_second.push_back(p0 + dirs[ii]);
				}
			}

			/*
				check if anything has changed.
				if not, just continue with the next node.
			 */
			/*
			if (
				 new_node_content == n0.getContent() 
				&& (nodemgr->get(n0.getContent()).liquid_type != LIQUID_FLOWING ||
				 (n0.getLevel(nodemgr) == (u8)new_node_level
				 //&& ((n0.param2 & LIQUID_FLOW_DOWN_MASK) ==
				 //LIQUID_FLOW_DOWN_MASK) == flowing_down
				 ))
				&&
				 (nodemgr->get(n0.getContent()).liquid_type != LIQUID_SOURCE ||
				 (((n0.param2 & LIQUID_INFINITY_MASK) ==
					LIQUID_INFINITY_MASK) == neighbors[i].i
				 ))
			   )*/
			if (liquid_levels[i] == new_node_level)
			{
				continue;
			}
			
			//++changed;

			/*
				update the current node
			 */
			/*
			if (nodemgr->get(new_node_content).liquid_type == LIQUID_FLOWING) {
				// set level to last 3 bits, flowing down bit to 4th bit
				n0.param2 = (new_node_level & LIQUID_LEVEL_MASK);
			} else if (nodemgr->get(new_node_content).liquid_type == LIQUID_SOURCE) {
				//n0.param2 = ~(LIQUID_LEVEL_MASK | LIQUID_FLOW_DOWN_MASK);
				n0.param2 = (neighbors[i].i ? LIQUID_INFINITY_MASK : 0x00);
			}
			*/
			/*
			infostream << "set node i=" <<(int)i<<" "<< PP(p0)<< " nc="
			<<new_node_content<< " p2="<<(int)n0.param2<< " nl="
			<<(int)new_node_level<<std::endl;
			*/
			
			n0.setContent(liquid_kind_flowing);
			n0.setLevel(nodemgr, new_node_level);
			// Find out whether there is a suspect for this action
			std::string suspect;
			if(m_gamedef->rollback()){
				suspect = m_gamedef->rollback()->getSuspect(p0, 83, 1);
			}

			if(!suspect.empty()){
				// Blame suspect
				RollbackScopeActor rollback_scope(m_gamedef->rollback(), suspect, true);
				// Get old node for rollback
				RollbackNode rollback_oldnode(this, p0, m_gamedef);
				// Set node
				setNode(p0, n0);
				// Report
				RollbackNode rollback_newnode(this, p0, m_gamedef);
				RollbackAction action;
				action.setSetNode(p0, rollback_oldnode, rollback_newnode);
				m_gamedef->rollback()->reportAction(action);
			} else {
				// Set node
				setNode(p0, n0);
			}

			v3s16 blockpos = getNodeBlockPos(p0);
			MapBlock *block = getBlockNoCreateNoEx(blockpos);
			if(block != NULL) {
				modified_blocks[blockpos] = block;
				// If node emits light, MapBlock requires lighting update
				if(nodemgr->get(n0).light_source != 0)
					lighting_modified_blocks[block->getPos()] = block;
			}
			must_reflow.push_back(neighbors[i].p);
		}
		/* //for better relax  only same level
		if (changed)  for (u16 ii = D_SELF + 1; ii < D_TOP; ++ii) {
			if (!neighbors[ii].l) continue;
			must_reflow.push_back(p0 + dirs[ii]);
		}*/
	}
	/*
	if (loopcount)
		infostream<<"Map::transformLiquids(): loopcount="<<loopcount
		<<" reflow="<<must_reflow.size()
		<<" queue="<< m_transforming_liquid.size()<<std::endl;
	*/
	while (must_reflow.size() > 0)
		m_transforming_liquid.push_back(must_reflow.pop_front());
	while (must_reflow_second.size() > 0)
		m_transforming_liquid.push_back(must_reflow_second.pop_front());
	updateLighting(lighting_modified_blocks, modified_blocks);
}