minetest/src/voxel.cpp

/*
Minetest-c55
Copyright (C) 2010 celeron55, Perttu Ahola <celeron55@gmail.com>

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License along
with this program; if not, write to the Free Software Foundation, Inc.,
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/

#include "voxel.h"
#include "map.h"

// For TimeTaker
#include "utility.h"
#include "gettime.h"

/*
	Debug stuff
*/
u32 addarea_time = 0;
u32 emerge_time = 0;
u32 emerge_load_time = 0;
u32 clearflag_time = 0;
//u32 getwaterpressure_time = 0;
//u32 spreadwaterpressure_time = 0;
u32 updateareawaterpressure_time = 0;
u32 flowwater_pre_time = 0;


VoxelManipulator::VoxelManipulator():
	m_data(NULL),
	m_flags(NULL)
{
	m_disable_water_climb = false;
}

VoxelManipulator::~VoxelManipulator()
{
	clear();
	if(m_data)
		delete[] m_data;
	if(m_flags)
		delete[] m_flags;
}

void VoxelManipulator::clear()
{
	// Reset area to volume=0
	m_area = VoxelArea();
	if(m_data)
		delete[] m_data;
	m_data = NULL;
	if(m_flags)
		delete[] m_flags;
	m_flags = NULL;
}

void VoxelManipulator::print(std::ostream &o, VoxelPrintMode mode)
{
	v3s16 em = m_area.getExtent();
	v3s16 of = m_area.MinEdge;
	o<<"size: "<<em.X<<"x"<<em.Y<<"x"<<em.Z
	 <<" offset: ("<<of.X<<","<<of.Y<<","<<of.Z<<")"<<std::endl;
	
	for(s32 y=m_area.MaxEdge.Y; y>=m_area.MinEdge.Y; y--)
	{
		if(em.X >= 3 && em.Y >= 3)
		{
			if     (y==m_area.MinEdge.Y+2) o<<"^     ";
			else if(y==m_area.MinEdge.Y+1) o<<"|     ";
			else if(y==m_area.MinEdge.Y+0) o<<"y x-> ";
			else                           o<<"      ";
		}

		for(s32 z=m_area.MinEdge.Z; z<=m_area.MaxEdge.Z; z++)
		{
			for(s32 x=m_area.MinEdge.X; x<=m_area.MaxEdge.X; x++)
			{
				u8 f = m_flags[m_area.index(x,y,z)];
				char c;
				if(f & VOXELFLAG_NOT_LOADED)
					c = 'N';
				else if(f & VOXELFLAG_INEXISTENT)
					c = 'I';
				else
				{
					c = 'X';
					u8 m = m_data[m_area.index(x,y,z)].d;
					u8 pr = m_data[m_area.index(x,y,z)].param2;
					if(mode == VOXELPRINT_MATERIAL)
					{
						if(m <= 9)
							c = m + '0';
					}
					else if(mode == VOXELPRINT_WATERPRESSURE)
					{
						if(m == CONTENT_WATER)
						{
							c = 'w';
							if(pr <= 9)
								c = pr + '0';
						}
						else if(liquid_replaces_content(m))
						{
							c = ' ';
						}
						else
						{
							c = '#';
						}
					}
				}
				o<<c;
			}
			o<<' ';
		}
		o<<std::endl;
	}
}

void VoxelManipulator::addArea(VoxelArea area)
{
	// Cancel if requested area has zero volume
	if(area.getExtent() == v3s16(0,0,0))
		return;
	
	// Cancel if m_area already contains the requested area
	if(m_area.contains(area))
		return;
	
	TimeTaker timer("addArea", &addarea_time);

	// Calculate new area
	VoxelArea new_area;
	// New area is the requested area if m_area has zero volume
	if(m_area.getExtent() == v3s16(0,0,0))
	{
		new_area = area;
	}
	// Else add requested area to m_area
	else
	{
		new_area = m_area;
		new_area.addArea(area);
	}

	s32 new_size = new_area.getVolume();

	/*dstream<<"adding area ";
	area.print(dstream);
	dstream<<", old area ";
	m_area.print(dstream);
	dstream<<", new area ";
	new_area.print(dstream);
	dstream<<", new_size="<<new_size;
	dstream<<std::endl;*/

	// Allocate and clear new data
	MapNode *new_data = new MapNode[new_size];
	u8 *new_flags = new u8[new_size];
	for(s32 i=0; i<new_size; i++)
	{
		new_flags[i] = VOXELFLAG_NOT_LOADED;
	}
	
	// Copy old data
	
	for(s32 z=m_area.MinEdge.Z; z<=m_area.MaxEdge.Z; z++)
	for(s32 y=m_area.MinEdge.Y; y<=m_area.MaxEdge.Y; y++)
	for(s32 x=m_area.MinEdge.X; x<=m_area.MaxEdge.X; x++)
	{
		// If loaded, copy data and flags
		if((m_flags[m_area.index(x,y,z)] & VOXELFLAG_NOT_LOADED) == false)
		{
			new_data[new_area.index(x,y,z)] = m_data[m_area.index(x,y,z)];
			new_flags[new_area.index(x,y,z)] = m_flags[m_area.index(x,y,z)];
		}
	}

	// Replace area, data and flags
	
	m_area = new_area;
	
	MapNode *old_data = m_data;
	u8 *old_flags = m_flags;

	/*dstream<<"old_data="<<(int)old_data<<", new_data="<<(int)new_data
	<<", old_flags="<<(int)m_flags<<", new_flags="<<(int)new_flags<<std::endl;*/

	m_data = new_data;
	m_flags = new_flags;
	
	if(old_data)
		delete[] old_data;
	if(old_flags)
		delete[] old_flags;

	//dstream<<"addArea done"<<std::endl;
}

void VoxelManipulator::copyFrom(MapNode *src, VoxelArea src_area,
		v3s16 from_pos, v3s16 to_pos, v3s16 size)
{
	for(s16 z=0; z<size.Z; z++)
	for(s16 y=0; y<size.Y; y++)
	{
		s32 i_src = src_area.index(from_pos.X, from_pos.Y+y, from_pos.Z+z);
		s32 i_local = m_area.index(to_pos.X, to_pos.Y+y, to_pos.Z+z);
		memcpy(&m_data[i_local], &src[i_src], size.X*sizeof(MapNode));
		memset(&m_flags[i_local], 0, size.X);
	}
}


void VoxelManipulator::clearFlag(u8 flags)
{
	// 0-1ms on moderate area
	TimeTaker timer("clearFlag", &clearflag_time);

	v3s16 s = m_area.getExtent();

	/*dstream<<"clearFlag clearing area of size "
			<<""<<s.X<<"x"<<s.Y<<"x"<<s.Z<<""
			<<std::endl;*/

	//s32 count = 0;

	/*for(s32 z=m_area.MinEdge.Z; z<=m_area.MaxEdge.Z; z++)
	for(s32 y=m_area.MinEdge.Y; y<=m_area.MaxEdge.Y; y++)
	for(s32 x=m_area.MinEdge.X; x<=m_area.MaxEdge.X; x++)
	{
		u8 f = m_flags[m_area.index(x,y,z)];
		m_flags[m_area.index(x,y,z)] &= ~flags;
		if(m_flags[m_area.index(x,y,z)] != f)
			count++;
	}*/

	s32 volume = m_area.getVolume();
	for(s32 i=0; i<volume; i++)
	{
		m_flags[i] &= ~flags;
	}

	/*s32 volume = m_area.getVolume();
	for(s32 i=0; i<volume; i++)
	{
		u8 f = m_flags[i];
		m_flags[i] &= ~flags;
		if(m_flags[i] != f)
			count++;
	}

	dstream<<"clearFlag changed "<<count<<" flags out of "
			<<volume<<" nodes"<<std::endl;*/
}

void VoxelManipulator::unspreadLight(enum LightBank bank, v3s16 p, u8 oldlight,
		core::map<v3s16, bool> & light_sources)
{
	v3s16 dirs[6] = {
		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
	};
	
	emerge(VoxelArea(p - v3s16(1,1,1), p + v3s16(1,1,1)));

	// Loop through 6 neighbors
	for(u16 i=0; i<6; i++)
	{
		// Get the position of the neighbor node
		v3s16 n2pos = p + dirs[i];
		
		u32 n2i = m_area.index(n2pos);

		if(m_flags[n2i] & VOXELFLAG_INEXISTENT)
			continue;

		MapNode &n2 = m_data[n2i];
		
		/*
			If the neighbor is dimmer than what was specified
			as oldlight (the light of the previous node)
		*/
		if(n2.getLight(bank) < oldlight)
		{
			/*
				And the neighbor is transparent and it has some light
			*/
			if(n2.light_propagates() && n2.getLight(bank) != 0)
			{
				/*
					Set light to 0 and add to queue
				*/

				u8 current_light = n2.getLight(bank);
				n2.setLight(bank, 0);
				
				unspreadLight(bank, n2pos, current_light, light_sources);
				
				/*
					Remove from light_sources if it is there
					NOTE: This doesn't happen nearly at all
				*/
				/*if(light_sources.find(n2pos))
				{
					std::cout<<"Removed from light_sources"<<std::endl;
					light_sources.remove(n2pos);
				}*/
			}
		}
		else{
			light_sources.insert(n2pos, true);
		}
	}
}

#if 1
/*
	Goes recursively through the neighbours of the node.

	Alters only transparent nodes.

	If the lighting of the neighbour is lower than the lighting of
	the node was (before changing it to 0 at the step before), the
	lighting of the neighbour is set to 0 and then the same stuff
	repeats for the neighbour.

	The ending nodes of the routine are stored in light_sources.
	This is useful when a light is removed. In such case, this
	routine can be called for the light node and then again for
	light_sources to re-light the area without the removed light.

	values of from_nodes are lighting values.
*/
void VoxelManipulator::unspreadLight(enum LightBank bank,
		core::map<v3s16, u8> & from_nodes,
		core::map<v3s16, bool> & light_sources)
{
	if(from_nodes.size() == 0)
		return;
	
	core::map<v3s16, u8>::Iterator j;
	j = from_nodes.getIterator();

	for(; j.atEnd() == false; j++)
	{
		v3s16 pos = j.getNode()->getKey();
		
		//MapNode &n = m_data[m_area.index(pos)];
		
		u8 oldlight = j.getNode()->getValue();

		unspreadLight(bank, pos, oldlight, light_sources);
	}
}
#endif

#if 0
/*
	Goes recursively through the neighbours of the node.

	Alters only transparent nodes.

	If the lighting of the neighbour is lower than the lighting of
	the node was (before changing it to 0 at the step before), the
	lighting of the neighbour is set to 0 and then the same stuff
	repeats for the neighbour.

	The ending nodes of the routine are stored in light_sources.
	This is useful when a light is removed. In such case, this
	routine can be called for the light node and then again for
	light_sources to re-light the area without the removed light.

	values of from_nodes are lighting values.
*/
void VoxelManipulator::unspreadLight(enum LightBank bank,
		core::map<v3s16, u8> & from_nodes,
		core::map<v3s16, bool> & light_sources)
{
	v3s16 dirs[6] = {
		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
	};
	
	if(from_nodes.size() == 0)
		return;
	
	core::map<v3s16, u8> unlighted_nodes;
	core::map<v3s16, u8>::Iterator j;
	j = from_nodes.getIterator();

	for(; j.atEnd() == false; j++)
	{
		v3s16 pos = j.getNode()->getKey();
		
		emerge(VoxelArea(pos - v3s16(1,1,1), pos + v3s16(1,1,1)));

		//MapNode &n = m_data[m_area.index(pos)];
		
		u8 oldlight = j.getNode()->getValue();
		
		// Loop through 6 neighbors
		for(u16 i=0; i<6; i++)
		{
			// Get the position of the neighbor node
			v3s16 n2pos = pos + dirs[i];
			
			u32 n2i = m_area.index(n2pos);

			if(m_flags[n2i] & VOXELFLAG_INEXISTENT)
				continue;

			MapNode &n2 = m_data[n2i];
			
			/*
				If the neighbor is dimmer than what was specified
				as oldlight (the light of the previous node)
			*/
			if(n2.getLight(bank) < oldlight)
			{
				/*
					And the neighbor is transparent and it has some light
				*/
				if(n2.light_propagates() && n2.getLight(bank) != 0)
				{
					/*
						Set light to 0 and add to queue
					*/

					u8 current_light = n2.getLight(bank);
					n2.setLight(bank, 0);

					unlighted_nodes.insert(n2pos, current_light);
					
					/*
						Remove from light_sources if it is there
						NOTE: This doesn't happen nearly at all
					*/
					/*if(light_sources.find(n2pos))
					{
						std::cout<<"Removed from light_sources"<<std::endl;
						light_sources.remove(n2pos);
					}*/
				}
			}
			else{
				light_sources.insert(n2pos, true);
			}
		}
	}

	/*dstream<<"unspreadLight(): Changed block "
			<<blockchangecount<<" times"
			<<" for "<<from_nodes.size()<<" nodes"
			<<std::endl;*/
	
	if(unlighted_nodes.size() > 0)
		unspreadLight(bank, unlighted_nodes, light_sources);
}
#endif

void VoxelManipulator::spreadLight(enum LightBank bank, v3s16 p)
{
	const v3s16 dirs[6] = {
		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
	};

	emerge(VoxelArea(p - v3s16(1,1,1), p + v3s16(1,1,1)));

	u32 i = m_area.index(p);
	
	if(m_flags[i] & VOXELFLAG_INEXISTENT)
		return;

	MapNode &n = m_data[i];

	u8 oldlight = n.getLight(bank);
	u8 newlight = diminish_light(oldlight);

	// Loop through 6 neighbors
	for(u16 i=0; i<6; i++)
	{
		// Get the position of the neighbor node
		v3s16 n2pos = p + dirs[i];
		
		u32 n2i = m_area.index(n2pos);

		if(m_flags[n2i] & VOXELFLAG_INEXISTENT)
			continue;

		MapNode &n2 = m_data[n2i];
		
		/*
			If the neighbor is brighter than the current node,
			add to list (it will light up this node on its turn)
		*/
		if(n2.getLight(bank) > undiminish_light(oldlight))
		{
			spreadLight(bank, n2pos);
		}
		/*
			If the neighbor is dimmer than how much light this node
			would spread on it, add to list
		*/
		if(n2.getLight(bank) < newlight)
		{
			if(n2.light_propagates())
			{
				n2.setLight(bank, newlight);
				spreadLight(bank, n2pos);
			}
		}
	}
}

#if 1
/*
	Lights neighbors of from_nodes, collects all them and then
	goes on recursively.
*/
void VoxelManipulator::spreadLight(enum LightBank bank,
		core::map<v3s16, bool> & from_nodes)
{
	if(from_nodes.size() == 0)
		return;
	
	core::map<v3s16, bool> lighted_nodes;
	core::map<v3s16, bool>::Iterator j;
	j = from_nodes.getIterator();

	for(; j.atEnd() == false; j++)
	{
		v3s16 pos = j.getNode()->getKey();

		spreadLight(bank, pos);
	}
}
#endif

#if 0
/*
	Lights neighbors of from_nodes, collects all them and then
	goes on recursively.
*/
void VoxelManipulator::spreadLight(enum LightBank bank,
		core::map<v3s16, bool> & from_nodes)
{
	const v3s16 dirs[6] = {
		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
	};

	if(from_nodes.size() == 0)
		return;
	
	core::map<v3s16, bool> lighted_nodes;
	core::map<v3s16, bool>::Iterator j;
	j = from_nodes.getIterator();

	for(; j.atEnd() == false; j++)
	{
		v3s16 pos = j.getNode()->getKey();

		emerge(VoxelArea(pos - v3s16(1,1,1), pos + v3s16(1,1,1)));

		u32 i = m_area.index(pos);
		
		if(m_flags[i] & VOXELFLAG_INEXISTENT)
			continue;

		MapNode &n = m_data[i];

		u8 oldlight = n.getLight(bank);
		u8 newlight = diminish_light(oldlight);

		// Loop through 6 neighbors
		for(u16 i=0; i<6; i++)
		{
			// Get the position of the neighbor node
			v3s16 n2pos = pos + dirs[i];
			
			try
			{
				u32 n2i = m_area.index(n2pos);

				if(m_flags[n2i] & VOXELFLAG_INEXISTENT)
					continue;

				MapNode &n2 = m_data[n2i];
				
				/*
					If the neighbor is brighter than the current node,
					add to list (it will light up this node on its turn)
				*/
				if(n2.getLight(bank) > undiminish_light(oldlight))
				{
					lighted_nodes.insert(n2pos, true);
				}
				/*
					If the neighbor is dimmer than how much light this node
					would spread on it, add to list
				*/
				if(n2.getLight(bank) < newlight)
				{
					if(n2.light_propagates())
					{
						n2.setLight(bank, newlight);
						lighted_nodes.insert(n2pos, true);
					}
				}
			}
			catch(InvalidPositionException &e)
			{
				continue;
			}
		}
	}

	/*dstream<<"spreadLight(): Changed block "
			<<blockchangecount<<" times"
			<<" for "<<from_nodes.size()<<" nodes"
			<<std::endl;*/
	
	if(lighted_nodes.size() > 0)
		spreadLight(bank, lighted_nodes);
}
#endif

#if 0
int VoxelManipulator::getWaterPressure(v3s16 p, s16 &highest_y, int recur_count)
{
	m_flags[m_area.index(p)] |= VOXELFLAG_CHECKED2;

	if(p.Y > highest_y)
		highest_y = p.Y;
	
	/*if(recur_count > 1000)
		throw ProcessingLimitException
				("getWaterPressure recur_count limit reached");*/
	
	if(recur_count > 10000)
		return -1;
	
	recur_count++;

	v3s16 dirs[6] = {
		v3s16(0,1,0), // top
		v3s16(0,0,1), // back
		v3s16(0,0,-1), // front
		v3s16(1,0,0), // right
		v3s16(-1,0,0), // left
		v3s16(0,-1,0), // bottom
	};

	// Load neighboring nodes
	emerge(VoxelArea(p - v3s16(1,1,1), p + v3s16(1,1,1)), 1);

	s32 i;
	for(i=0; i<6; i++)
	{
		v3s16 p2 = p + dirs[i];
		u8 f = m_flags[m_area.index(p2)];
		// Ignore inexistent or checked nodes
		if(f & (VOXELFLAG_INEXISTENT | VOXELFLAG_CHECKED2))
			continue;
		MapNode &n = m_data[m_area.index(p2)];
		// Ignore non-liquid nodes
		if(content_liquid(n.d) == false)
			continue;

		int pr;

		// If at ocean surface
		if(n.pressure == 1 && n.d == CONTENT_WATERSOURCE)
		//if(n.pressure == 1) // Causes glitches but is fast
		{
			pr = 1;
		}
		// Otherwise recurse more
		else
		{
			pr = getWaterPressure(p2, highest_y, recur_count);
			if(pr == -1)
				continue;
		}

		// If block is at top, pressure here is one higher
		if(i == 0)
		{
			if(pr < 255)
				pr++;
		}
		// If block is at bottom, pressure here is one lower
		else if(i == 5)
		{
			if(pr > 1)
				pr--;
		}
		
		// Node is on the pressure route
		m_flags[m_area.index(p)] |= VOXELFLAG_CHECKED4;

		// Got pressure
		return pr;
	}
	
	// Nothing useful found
	return -1;
}

void VoxelManipulator::spreadWaterPressure(v3s16 p, int pr,
		VoxelArea request_area,
		core::map<v3s16, u8> &active_nodes,
		int recur_count)
{
	//if(recur_count > 10000)
		/*throw ProcessingLimitException
				("spreadWaterPressure recur_count limit reached");*/
	if(recur_count > 10)
		return;
	recur_count++;
	
	/*dstream<<"spreadWaterPressure: p=("
			<<p.X<<","<<p.Y<<","<<p.Z<<")"
			<<", oldpr="<<(int)m_data[m_area.index(p)].pressure
			<<", pr="<<pr
			<<", recur_count="<<recur_count
			<<", request_area=";
	request_area.print(dstream);
	dstream<<std::endl;*/

	m_flags[m_area.index(p)] |= VOXELFLAG_CHECKED3;
	m_data[m_area.index(p)].pressure = pr;

	v3s16 dirs[6] = {
		v3s16(0,1,0), // top
		v3s16(-1,0,0), // left
		v3s16(1,0,0), // right
		v3s16(0,0,-1), // front
		v3s16(0,0,1), // back
		v3s16(0,-1,0), // bottom
	};

	// Load neighboring nodes
	emerge(VoxelArea(p - v3s16(1,1,1), p + v3s16(1,1,1)), 2);

	s32 i;
	for(i=0; i<6; i++)
	{
		v3s16 p2 = p + dirs[i];
		
		u8 f = m_flags[m_area.index(p2)];

		// Ignore inexistent and checked nodes
		if(f & (VOXELFLAG_INEXISTENT | VOXELFLAG_CHECKED3))
			continue;

		MapNode &n = m_data[m_area.index(p2)];
		
		/*
			If material is air:
				add to active_nodes if there is flow-causing pressure.
			NOTE: Do not remove anything from there. We cannot know
			      here if some other neighbor of it causes flow.
		*/
		if(liquid_replaces_content(n.d))
		{
			bool pressure_causes_flow = false;
			// If empty block is at top
			if(i == 0)
			{
				if(m_disable_water_climb)
					continue;
				
				//if(pr >= PRESERVE_WATER_VOLUME ? 3 : 2)
				if(pr >= 3)
					pressure_causes_flow = true;
			}
			// If block is at bottom
			else if(i == 5)
			{
				pressure_causes_flow = true;
			}
			// If block is at side
			else
			{
				//if(pr >= PRESERVE_WATER_VOLUME ? 2 : 1)
				if(pr >= 2)
					pressure_causes_flow = true;
			}
			
			if(pressure_causes_flow)
			{
				active_nodes[p2] = 1;
			}

			continue;
		}

		// Ignore non-liquid nodes
		if(content_liquid(n.d) == false)
			continue;

		int pr2 = pr;
		// If block is at top, pressure there is lower
		if(i == 0)
		{
			if(pr2 > 0)
				pr2--;
		}
		// If block is at bottom, pressure there is higher
		else if(i == 5)
		{
			if(pr2 < 255)
				pr2++;
		}

		/*if(m_disable_water_climb)
		{
			if(pr2 > 3)
				pr2 = 3;
		}*/
		
		// Ignore if correct pressure is already set and is not on
		// request_area.
		// Thus, request_area can be used for updating as much
		// pressure info in some area as possible to possibly
		// make some calls to getWaterPressure unnecessary.
		if(n.pressure == pr2 && request_area.contains(p2) == false)
			continue;

		spreadWaterPressure(p2, pr2, request_area, active_nodes, recur_count);
	}
}

void VoxelManipulator::updateAreaWaterPressure(VoxelArea a,
		core::map<v3s16, u8> &active_nodes,
		bool checked3_is_clear)
{
	TimeTaker timer("updateAreaWaterPressure", &updateareawaterpressure_time);

	emerge(a, 3);
	
	bool checked2_clear = false;
	
	if(checked3_is_clear == false)
	{
		//clearFlag(VOXELFLAG_CHECKED3);

		clearFlag(VOXELFLAG_CHECKED3 | VOXELFLAG_CHECKED2);
		checked2_clear = true;
	}
	

	for(s32 z=a.MinEdge.Z; z<=a.MaxEdge.Z; z++)
	for(s32 y=a.MinEdge.Y; y<=a.MaxEdge.Y; y++)
	for(s32 x=a.MinEdge.X; x<=a.MaxEdge.X; x++)
	{
		v3s16 p(x,y,z);

		u8 f = m_flags[m_area.index(p)];
		// Ignore inexistent or checked nodes
		if(f & (VOXELFLAG_INEXISTENT | VOXELFLAG_CHECKED3))
			continue;
		MapNode &n = m_data[m_area.index(p)];
		// Ignore non-liquid nodes
		if(content_liquid(n.d) == false)
			continue;
		
		if(checked2_clear == false)
		{
			clearFlag(VOXELFLAG_CHECKED2);
			checked2_clear = true;
		}

		checked2_clear = false;

		s16 highest_y = -32768;
		int recur_count = 0;
		int pr = -1;

		try
		{
			// 0-1ms @ recur_count <= 100
			//TimeTaker timer("getWaterPressure", g_irrlicht);
			pr = getWaterPressure(p, highest_y, recur_count);
		}
		catch(ProcessingLimitException &e)
		{
			//dstream<<"getWaterPressure ProcessingLimitException"<<std::endl;
		}

		if(pr == -1)
		{
			assert(highest_y != -32768);

			pr = highest_y - p.Y + 1;
			if(pr > 255)
				pr = 255;

			/*dstream<<"WARNING: Pressure at ("
					<<p.X<<","<<p.Y<<","<<p.Z<<")"
					<<" = "<<pr
					//<<" and highest_y == -32768"
					<<std::endl;
			assert(highest_y != -32768);
			continue;*/
		}
		
		try
		{
			// 0ms
			//TimeTaker timer("spreadWaterPressure", g_irrlicht);
			spreadWaterPressure(p, pr, a, active_nodes, 0);
		}
		catch(ProcessingLimitException &e)
		{
			//dstream<<"getWaterPressure ProcessingLimitException"<<std::endl;
		}
	}
}

bool VoxelManipulator::flowWater(v3s16 removed_pos,
		core::map<v3s16, u8> &active_nodes,
		int recursion_depth, bool debugprint,
		u32 stoptime)
{
	v3s16 dirs[6] = {
		v3s16(0,1,0), // top
		v3s16(0,0,-1), // front
		v3s16(0,0,1), // back
		v3s16(-1,0,0), // left
		v3s16(1,0,0), // right
		v3s16(0,-1,0), // bottom
	};

	recursion_depth++;

	v3s16 p;
	bool from_ocean = false;
	
	// Randomize horizontal order
	static s32 cs = 0;
	if(cs < 3)
		cs++;
	else
		cs = 0;
	s16 s1 = (cs & 1) ? 1 : -1;
	s16 s2 = (cs & 2) ? 1 : -1;
	//dstream<<"s1="<<s1<<", s2="<<s2<<std::endl;

	{
	TimeTaker timer1("flowWater pre", &flowwater_pre_time);
	
	// Load neighboring nodes
	emerge(VoxelArea(removed_pos - v3s16(1,1,1), removed_pos + v3s16(1,1,1)), 4);
	
	// Ignore incorrect removed_pos
	{
		u8 f = m_flags[m_area.index(removed_pos)];
		// Ignore inexistent or checked node
		if(f & (VOXELFLAG_INEXISTENT | VOXELFLAG_CHECKED))
			return false;
		MapNode &n = m_data[m_area.index(removed_pos)];
		// Ignore nodes to which the water can't go
		if(liquid_replaces_content(n.d) == false)
			return false;
	}
	
	s32 i;
	for(i=0; i<6; i++)
	{
		// Don't raise water from bottom
		if(m_disable_water_climb && i == 5)
			continue;

		p = removed_pos + v3s16(s1*dirs[i].X, dirs[i].Y, s2*dirs[i].Z);

		u8 f = m_flags[m_area.index(p)];
		// Inexistent or checked nodes can't move
		if(f & (VOXELFLAG_INEXISTENT | VOXELFLAG_CHECKED))
			continue;
		MapNode &n = m_data[m_area.index(p)];
		// Only liquid nodes can move
		if(content_liquid(n.d) == false)
			continue;
		// If block is at top, select it always
		if(i == 0)
		{
			break;
		}
		// If block is at bottom, select it if it has enough pressure
		if(i == 5)
		{
			//if(n.pressure >= PRESERVE_WATER_VOLUME ? 3 : 2)
			if(n.pressure >= 3)
				break;
			continue;
		}
		// Else block is at some side. Select it if it has enough pressure
		//if(n.pressure >= PRESERVE_WATER_VOLUME ? 2 : 1)
		if(n.pressure >= 2)
		{
			break;
		}
	}

	// If there is nothing to move, return
	if(i==6)
		return false;

	/*
		Move water and bubble
	*/

	u8 m = m_data[m_area.index(p)].d;
	u8 f = m_flags[m_area.index(p)];

	if(m == CONTENT_WATERSOURCE)
		from_ocean = true;

	// Move air bubble if not taking water from ocean
	if(from_ocean == false)
	{
		m_data[m_area.index(p)].d = m_data[m_area.index(removed_pos)].d;
		m_flags[m_area.index(p)] = m_flags[m_area.index(removed_pos)];
	}
	
	/*
		This has to be done to copy the brightness of a light source
		correctly. Otherwise unspreadLight will fuck up when water
		has replaced a light source.
	*/
	u8 light = m_data[m_area.index(removed_pos)].getLightBanksWithSource();

	m_data[m_area.index(removed_pos)].d = m;
	m_flags[m_area.index(removed_pos)] = f;

	m_data[m_area.index(removed_pos)].setLightBanks(light);
	
	// Mark removed_pos checked
	m_flags[m_area.index(removed_pos)] |= VOXELFLAG_CHECKED;

	// If block was dropped from surface, increase pressure
	if(i == 0 && m_data[m_area.index(removed_pos)].pressure == 1)
	{
		m_data[m_area.index(removed_pos)].pressure = 2;
	}
	
	/*
	NOTE: This does not work as-is
	if(m == CONTENT_WATERSOURCE)
	{
		// If block was raised to surface, increase pressure of
		// source node
		if(i == 5 && m_data[m_area.index(p)].pressure == 1)
		{
			m_data[m_area.index(p)].pressure = 2;
		}
	}*/
	
	/*if(debugprint)
	{
		dstream<<"VoxelManipulator::flowWater(): Moved bubble:"<<std::endl;
		print(dstream, VOXELPRINT_WATERPRESSURE);
	}*/

	// Update pressure
	VoxelArea a;
	a.addPoint(p - v3s16(1,1,1));
	a.addPoint(p + v3s16(1,1,1));
	a.addPoint(removed_pos - v3s16(1,1,1));
	a.addPoint(removed_pos + v3s16(1,1,1));
	updateAreaWaterPressure(a, active_nodes);
	
	/*if(debugprint)
	{
		dstream<<"VoxelManipulator::flowWater(): Pressure updated:"<<std::endl;
		print(dstream, VOXELPRINT_WATERPRESSURE);
		//std::cin.get();
	}*/

	if(debugprint)
	{
		dstream<<"VoxelManipulator::flowWater(): step done:"<<std::endl;
		print(dstream, VOXELPRINT_WATERPRESSURE);
		//std::cin.get();
	}
	
	}//timer1
	
	//if(PRESERVE_WATER_VOLUME)
	if(from_ocean == false)
	{
		// Flow water to the newly created empty position
		/*flowWater(p, active_nodes, recursion_depth,
				debugprint, counter, counterlimit);*/
		flowWater(p, active_nodes, recursion_depth,
				debugprint, stoptime);
	}
	
	if(stoptime != 0)
	{
		u32 timenow = getTimeMs();
		// Well, it is a bit hard to guess because we don't know the
		// start time...
		bool overflow = timenow < stoptime - 100000;
		if(timenow >= stoptime || overflow)
		{
			dstream<<"flowWater: stoptime reached"<<std::endl;
			throw ProcessingLimitException("flowWater stoptime reached");
		}
	}
	
find_again:
	
	// Try flowing water to empty positions around removed_pos.
	// They are checked in reverse order compared to the previous loop.
	for(s32 i=5; i>=0; i--)
	{
		// Don't try to flow to top
		if(m_disable_water_climb && i == 0)
			continue;

		//v3s16 p = removed_pos + dirs[i];
		p = removed_pos + v3s16(s1*dirs[i].X, dirs[i].Y, s2*dirs[i].Z);

		u8 f = m_flags[m_area.index(p)];
		// Water can't move to inexistent nodes
		if(f & VOXELFLAG_INEXISTENT)
			continue;
		MapNode &n = m_data[m_area.index(p)];
		// Water can only move to air
		if(liquid_replaces_content(n.d) == false)
			continue;
			
		// Flow water to node
		bool moved =
		flowWater(p, active_nodes, recursion_depth,
				debugprint, stoptime);
		/*flowWater(p, active_nodes, recursion_depth,
				debugprint, counter, counterlimit);*/
		
		if(moved)
		{
			// Search again from all neighbors
			goto find_again;
		}
	}

	return true;
}

void VoxelManipulator::flowWater(
		core::map<v3s16, u8> &active_nodes,
		int recursion_depth, bool debugprint,
		u32 timelimit)
{
	addarea_time = 0;
	emerge_time = 0;
	emerge_load_time = 0;
	clearflag_time = 0;
	updateareawaterpressure_time = 0;
	flowwater_pre_time = 0;

	if(active_nodes.size() == 0)
	{
		dstream<<"flowWater: no active nodes"<<std::endl;
		return;
	}

	//TimeTaker timer1("flowWater (active_nodes)", g_irrlicht);

	//dstream<<"active_nodes.size() = "<<active_nodes.size()<<std::endl;


	u32 stoptime = 0;
	stoptime = getTimeMs() + timelimit;

	// Count of handled active nodes
	u32 handled_count = 0;

	try
	{

	/*
		Take random one at first

		This is randomized only at the first time so that all
		subsequent nodes will be taken at roughly the same position
	*/
	s32 k = 0;
	if(active_nodes.size() != 0)
		k = (s32)myrand() % (s32)active_nodes.size();

	// Flow water to active nodes
	for(;;)
	//for(s32 h=0; h<1; h++)
	{
		if(active_nodes.size() == 0)
			break;

		handled_count++;
		
		// Clear check flags
		clearFlag(VOXELFLAG_CHECKED);
		
		//dstream<<"Selecting a new active_node"<<std::endl;

#if 0
		// Take first one
		core::map<v3s16, u8>::Node
				*n = active_nodes.getIterator().getNode();
#endif

#if 1
		
		core::map<v3s16, u8>::Iterator
				i = active_nodes.getIterator().getNode();
		for(s32 j=0; j<k; j++)
		{
			i++;
		}
		core::map<v3s16, u8>::Node *n = i.getNode();

		// Decrement index if less than 0.
		// This keeps us in existing indices always.
		if(k > 0)
			k--;
#endif

		v3s16 p = n->getKey();
		active_nodes.remove(p);
		flowWater(p, active_nodes, recursion_depth,
				debugprint, stoptime);
	}

	}
	catch(ProcessingLimitException &e)
	{
		//dstream<<"getWaterPressure ProcessingLimitException"<<std::endl;
	}
	
	/*v3s16 e = m_area.getExtent();
	s32 v = m_area.getVolume();
	dstream<<"flowWater (active): "
			<<"area ended up as "
			<<e.X<<"x"<<e.Y<<"x"<<e.Z<<" = "<<v
			<<", handled a_node count: "<<handled_count
			<<", active_nodes.size() = "<<active_nodes.size()
			<<std::endl;
	dstream<<"addarea_time: "<<addarea_time
			<<", emerge_time: "<<emerge_time
			<<", emerge_load_time: "<<emerge_load_time
			<<", clearflag_time: "<<clearflag_time
			<<", flowwater_pre_time: "<<flowwater_pre_time
			<<", updateareawaterpressure_time: "<<updateareawaterpressure_time
			<<std::endl;*/
}
#endif

//END