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/*
Minetest
Copyright (C) 2016 MillersMan <millersman@users.noreply.github.com>
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 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 Lesser General Public License for more details.
You should have received a copy of the GNU Lesser 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 "reflowscan.h"
#include "map.h"
#include "mapblock.h"
#include "nodedef.h"
#include "util/timetaker.h"
ReflowScan::ReflowScan(Map *map, const NodeDefManager *ndef) :
m_map(map),
m_ndef(ndef)
{
}
void ReflowScan::scan(MapBlock *block, UniqueQueue<v3s16> *liquid_queue)
{
m_block_pos = block->getPos();
m_rel_block_pos = block->getPosRelative();
m_liquid_queue = liquid_queue;
// Prepare the lookup which is a 3x3x3 array of the blocks surrounding the
// scanned block. Blocks are only added to the lookup if they are really
// needed. The lookup is indexed manually to use the same index in a
// bit-array (of uint32 type) which stores for unloaded blocks that they
// were already fetched from Map but were actually nullptr.
memset(m_lookup, 0, sizeof(m_lookup));
int block_idx = 1 + (1 * 9) + (1 * 3);
m_lookup[block_idx] = block;
m_lookup_state_bitset = 1 << block_idx;
// Scan the columns in the block
for (s16 z = 0; z < MAP_BLOCKSIZE; z++)
for (s16 x = 0; x < MAP_BLOCKSIZE; x++) {
scanColumn(x, z);
}
// Scan neighbouring columns from the nearby blocks as they might contain
// liquid nodes that weren't allowed to flow to prevent gaps.
for (s16 i = 0; i < MAP_BLOCKSIZE; i++) {
scanColumn(i, -1);
scanColumn(i, MAP_BLOCKSIZE);
scanColumn(-1, i);
scanColumn(MAP_BLOCKSIZE, i);
}
}
inline MapBlock *ReflowScan::lookupBlock(int x, int y, int z)
{
// Gets the block that contains (x,y,z) relativ to the scanned block.
// This uses a lookup as there might be many lookups into the same
// neighbouring block which makes fetches from Map costly.
int bx = (MAP_BLOCKSIZE + x) / MAP_BLOCKSIZE;
int by = (MAP_BLOCKSIZE + y) / MAP_BLOCKSIZE;
int bz = (MAP_BLOCKSIZE + z) / MAP_BLOCKSIZE;
int idx = (bx + (by * 9) + (bz * 3));
MapBlock *result = m_lookup[idx];
if (!result && (m_lookup_state_bitset & (1 << idx)) == 0) {
// The block wasn't requested yet so fetch it from Map and store it
// in the lookup
v3s16 pos = m_block_pos + v3s16(bx - 1, by - 1, bz - 1);
m_lookup[idx] = result = m_map->getBlockNoCreateNoEx(pos);
m_lookup_state_bitset |= (1 << idx);
}
return result;
}
inline bool ReflowScan::isLiquidFlowableTo(int x, int y, int z)
{
// Tests whether (x,y,z) is a node to which liquid might flow.
bool valid_position;
MapBlock *block = lookupBlock(x, y, z);
if (block) {
int dx = (MAP_BLOCKSIZE + x) % MAP_BLOCKSIZE;
int dy = (MAP_BLOCKSIZE + y) % MAP_BLOCKSIZE;
int dz = (MAP_BLOCKSIZE + z) % MAP_BLOCKSIZE;
MapNode node = block->getNodeNoCheck(dx, dy, dz, &valid_position);
if (node.getContent() != CONTENT_IGNORE) {
const ContentFeatures &f = m_ndef->get(node);
// NOTE: No need to check for flowing nodes with lower liquid level
// as they should only occur on top of other columns where they
// will be added to the queue themselves.
return f.floodable;
}
}
return false;
}
inline bool ReflowScan::isLiquidHorizontallyFlowable(int x, int y, int z)
{
// Check if the (x,y,z) might spread to one of the horizontally
// neighbouring nodes
return isLiquidFlowableTo(x - 1, y, z) ||
isLiquidFlowableTo(x + 1, y, z) ||
isLiquidFlowableTo(x, y, z - 1) ||
isLiquidFlowableTo(x, y, z + 1);
}
void ReflowScan::scanColumn(int x, int z)
{
bool valid_position;
// Is the column inside a loaded block?
MapBlock *block = lookupBlock(x, 0, z);
if (!block)
return;
MapBlock *above = lookupBlock(x, MAP_BLOCKSIZE, z);
int dx = (MAP_BLOCKSIZE + x) % MAP_BLOCKSIZE;
int dz = (MAP_BLOCKSIZE + z) % MAP_BLOCKSIZE;
// Get the state from the node above the scanned block
bool was_ignore, was_liquid;
if (above) {
MapNode node = above->getNodeNoCheck(dx, 0, dz, &valid_position);
was_ignore = node.getContent() == CONTENT_IGNORE;
was_liquid = m_ndef->get(node).isLiquid();
} else {
was_ignore = true;
was_liquid = false;
}
bool was_checked = false;
bool was_pushed = false;
// Scan through the whole block
for (s16 y = MAP_BLOCKSIZE - 1; y >= 0; y--) {
MapNode node = block->getNodeNoCheck(dx, y, dz, &valid_position);
const ContentFeatures &f = m_ndef->get(node);
bool is_ignore = node.getContent() == CONTENT_IGNORE;
bool is_liquid = f.isLiquid();
if (is_ignore || was_ignore || is_liquid == was_liquid) {
// Neither topmost node of liquid column nor topmost node below column
was_checked = false;
was_pushed = false;
} else if (is_liquid) {
// This is the topmost node in the column
bool is_pushed = false;
if (f.liquid_type == LIQUID_FLOWING ||
isLiquidHorizontallyFlowable(x, y, z)) {
m_liquid_queue->push_back(m_rel_block_pos + v3s16(x, y, z));
is_pushed = true;
}
// Remember waschecked and waspushed to avoid repeated
// checks/pushes in case the column consists of only this node
was_checked = true;
was_pushed = is_pushed;
} else {
// This is the topmost node below a liquid column
if (!was_pushed && (f.floodable ||
(!was_checked && isLiquidHorizontallyFlowable(x, y + 1, z)))) {
// Activate the lowest node in the column which is one
// node above this one
m_liquid_queue->push_back(m_rel_block_pos + v3s16(x, y + 1, z));
}
}
was_liquid = is_liquid;
was_ignore = is_ignore;
}
// Check the node below the current block
MapBlock *below = lookupBlock(x, -1, z);
if (below) {
MapNode node = below->getNodeNoCheck(dx, MAP_BLOCKSIZE - 1, dz, &valid_position);
const ContentFeatures &f = m_ndef->get(node);
bool is_ignore = node.getContent() == CONTENT_IGNORE;
bool is_liquid = f.isLiquid();
if (is_ignore || was_ignore || is_liquid == was_liquid) {
// Neither topmost node of liquid column nor topmost node below column
} else if (is_liquid) {
// This is the topmost node in the column and might want to flow away
if (f.liquid_type == LIQUID_FLOWING ||
isLiquidHorizontallyFlowable(x, -1, z)) {
m_liquid_queue->push_back(m_rel_block_pos + v3s16(x, -1, z));
}
} else {
// This is the topmost node below a liquid column
if (!was_pushed && (f.floodable ||
(!was_checked && isLiquidHorizontallyFlowable(x, 0, z)))) {
// Activate the lowest node in the column which is one
// node above this one
m_liquid_queue->push_back(m_rel_block_pos + v3s16(x, 0, z));
}
}
}
}
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