transformLiquid: small optimization and whitespace cleanup
[oweals/minetest.git] / src / map.cpp
index 1c63943c4c775f696a8bebef3b428b5b8f6bb85b..a540860bc225b6d84772be53f3de7f516d58929c 100644 (file)
@@ -1086,7 +1086,7 @@ void Map::addNodeAndUpdate(v3s16 p, MapNode n,
                v3s16 p2 = p + dirs[i];
 
                MapNode n2 = getNode(p2);
-               if(content_liquid(n2.getContent()))
+               if(content_liquid(n2.getContent()) || n2.getContent() == CONTENT_AIR)
                {
                        m_transforming_liquid.push_back(p2);
                }
@@ -1260,7 +1260,7 @@ void Map::removeNodeAndUpdate(v3s16 p,
                v3s16 p2 = p + dirs[i];
 
                MapNode n2 = getNode(p2);
-               if(content_liquid(n2.getContent()))
+               if(content_liquid(n2.getContent()) || n2.getContent() == CONTENT_AIR)
                {
                        m_transforming_liquid.push_back(p2);
                }
@@ -1540,6 +1540,17 @@ void Map::PrintInfo(std::ostream &out)
 
 #define WATER_DROP_BOOST 4
 
+enum NeighborType {
+       NEIGHBOR_UPPER,
+       NEIGHBOR_SAME_LEVEL,
+       NEIGHBOR_LOWER
+};
+struct NodeNeighbor {
+       MapNode n;
+       NeighborType t;
+       v3s16 p;
+};
+
 void Map::transformLiquids(core::map<v3s16, MapBlock*> & modified_blocks)
 {
        DSTACK(__FUNCTION_NAME);
@@ -1553,6 +1564,11 @@ void Map::transformLiquids(core::map<v3s16, MapBlock*> & modified_blocks)
 
        while(m_transforming_liquid.size() != 0)
        {
+               // This should be done here so that it is done when continue is used
+               if(loopcount >= initial_size * 3)
+                       break;
+               loopcount++;
+
                /*
                        Get a queued transforming liquid node
                */
@@ -1560,239 +1576,207 @@ void Map::transformLiquids(core::map<v3s16, MapBlock*> & modified_blocks)
 
                MapNode n0 = getNodeNoEx(p0);
 
-               // Don't deal with non-liquids
-               if(content_liquid(n0.getContent()) == false)
-                       continue;
-
-               bool is_source = !content_flowing_liquid(n0.getContent());
-
-               u8 liquid_level = 8;
-               if(is_source == false)
-                       liquid_level = n0.param2 & 0x0f;
-
-               // Turn possible source into non-source
-               u8 nonsource_c = make_liquid_flowing(n0.getContent());
-
                /*
-                       If not source, check that some node flows into this one
-                       and what is the level of liquid in this one
-               */
-               if(is_source == false)
-               {
-                       s8 new_liquid_level_max = -1;
-
-                       v3s16 dirs_from[5] = {
-                               v3s16(0,1,0), // top
-                               v3s16(0,0,1), // back
-                               v3s16(1,0,0), // right
-                               v3s16(0,0,-1), // front
-                               v3s16(-1,0,0), // left
-                       };
-                       for(u16 i=0; i<5; i++)
-                       {
-                               bool from_top = (i==0);
-
-                               v3s16 p2 = p0 + dirs_from[i];
-                               MapNode n2 = getNodeNoEx(p2);
-
-                               if(content_liquid(n2.getContent()))
-                               {
-                                       u8 n2_nonsource_c = make_liquid_flowing(n2.getContent());
-                                       // Check that the liquids are the same type
-                                       if(n2_nonsource_c != nonsource_c)
-                                       {
-                                               dstream<<"WARNING: Not handling: different liquids"
-                                                               " collide"<<std::endl;
-                                               continue;
-                                       }
-                                       bool n2_is_source = !content_flowing_liquid(n2.getContent());
-                                       s8 n2_liquid_level = 8;
-                                       if(n2_is_source == false)
-                                               n2_liquid_level = n2.param2 & 0x07;
+                       Collect information about current node
+                */
+               s8 liquid_level = -1;
+               u8 liquid_kind = CONTENT_IGNORE;
+               LiquidType liquid_type = content_features(n0.getContent()).liquid_type;
+               switch (liquid_type) {
+                       case LIQUID_SOURCE:
+                               liquid_level = 8;
+                               liquid_kind = content_features(n0.getContent()).liquid_alternative_flowing;
+                               break;
+                       case LIQUID_FLOWING:
+                               liquid_level = (n0.param2 & LIQUID_LEVEL_MASK);
+                               liquid_kind = n0.getContent();
+                               break;
+                       case LIQUID_NONE:
+                               // if this is an air node, it *could* be transformed into a liquid. otherwise,
+                               // continue with the next node.
+                               if (n0.getContent() != CONTENT_AIR)
+                                       continue;
+                               liquid_kind = CONTENT_AIR;
+                               break;
+               }
 
-                                       s8 new_liquid_level = -1;
-                                       if(from_top)
-                                       {
-                                               //new_liquid_level = 7;
-                                               if(n2_liquid_level >= 7 - WATER_DROP_BOOST)
-                                                       new_liquid_level = 7;
-                                               else
-                                                       new_liquid_level = n2_liquid_level + WATER_DROP_BOOST;
+               /*
+                       Collect information about the environment
+                */
+               const v3s16 *dirs = g_6dirs;
+               NodeNeighbor sources[6]; // surrounding sources
+               int num_sources = 0;
+               NodeNeighbor flows[6]; // surrounding flowing liquid nodes
+               int num_flows = 0;
+               NodeNeighbor airs[6]; // surrounding air
+               int num_airs = 0;
+               NodeNeighbor neutrals[6]; // nodes that are solid or another kind of liquid
+               int num_neutrals = 0;
+               bool flowing_down = false;
+               for (u16 i = 0; i < 6; i++) {
+                       NeighborType nt = NEIGHBOR_SAME_LEVEL;
+                       switch (i) {
+                               case 1:
+                                       nt = NEIGHBOR_UPPER;
+                                       break;
+                               case 4:
+                                       nt = NEIGHBOR_LOWER;
+                                       break;
+                       }
+                       v3s16 npos = p0 + dirs[i];
+                       NodeNeighbor nb = {getNodeNoEx(npos), nt, npos};
+                       switch (content_features(nb.n.getContent()).liquid_type) {
+                               case LIQUID_NONE:
+                                       if (nb.n.getContent() == CONTENT_AIR) {
+                                               airs[num_airs++] = nb;
+                                               // if the current node happens to be a flowing node, it will start to flow down here.
+                                               if (nb.t == NEIGHBOR_LOWER)
+                                                       flowing_down = true;
+                                       } else {
+                                               neutrals[num_neutrals++] = nb;
                                        }
-                                       else if(n2_liquid_level > 0)
-                                       {
-                                               new_liquid_level = n2_liquid_level - 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 == CONTENT_AIR)
+                                               liquid_kind = content_features(nb.n.getContent()).liquid_alternative_flowing;
+                                       if (content_features(nb.n.getContent()).liquid_alternative_flowing !=liquid_kind) {
+                                               neutrals[num_neutrals++] = nb;
+                                       } else {
+                                               sources[num_sources++] = nb;
                                        }
-
-                                       if(new_liquid_level > new_liquid_level_max)
-                                               new_liquid_level_max = new_liquid_level;
-                               }
-                       } //for
-
-                       /*
-                               If liquid level should be something else, update it and
-                               add all the neighboring water nodes to the transform queue.
-                       */
-                       if(new_liquid_level_max != liquid_level)
-                       {
-                               if(new_liquid_level_max == -1)
-                               {
-                                       // Remove water alltoghether
-                                       n0.setContent(CONTENT_AIR);
-                                       n0.param2 = 0;
-                                       setNode(p0, n0);
-                               }
-                               else
-                               {
-                                       n0.param2 = new_liquid_level_max;
-                                       setNode(p0, n0);
-                               }
-
-                               // Block has been modified
-                               {
-                                       v3s16 blockpos = getNodeBlockPos(p0);
-                                       MapBlock *block = getBlockNoCreateNoEx(blockpos);
-                                       if(block != NULL)
-                                               modified_blocks.insert(blockpos, block);
-                               }
-
-                               /*
-                                       Add neighboring non-source liquid nodes to transform queue.
-                               */
-                               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
-                               };
-                               for(u16 i=0; i<6; i++)
-                               {
-                                       v3s16 p2 = p0 + dirs[i];
-
-                                       MapNode n2 = getNodeNoEx(p2);
-                                       if(content_flowing_liquid(n2.getContent()))
-                                       {
-                                               m_transforming_liquid.push_back(p2);
+                                       break;
+                               case LIQUID_FLOWING:
+                                       // if this node is not (yet) of a liquid type, choose the first liquid type we encounter
+                                       if (liquid_kind == CONTENT_AIR)
+                                               liquid_kind = content_features(nb.n.getContent()).liquid_alternative_flowing;
+                                       if (content_features(nb.n.getContent()).liquid_alternative_flowing != liquid_kind) {
+                                               neutrals[num_neutrals++] = nb;
+                                       } else {
+                                               flows[num_flows++] = nb;
+                                               if (nb.t == NEIGHBOR_LOWER)
+                                                       flowing_down = true;
                                        }
-                               }
+                                       break;
                        }
                }
 
-               // Get a new one from queue if the node has turned into non-water
-               if(content_liquid(n0.getContent()) == false)
-                       continue;
-
                /*
-                       Flow water from this node
-               */
-               v3s16 dirs_to[5] = {
-                       v3s16(0,-1,0), // bottom
-                       v3s16(0,0,1), // back
-                       v3s16(1,0,0), // right
-                       v3s16(0,0,-1), // front
-                       v3s16(-1,0,0), // left
-               };
-               for(u16 i=0; i<5; i++)
-               {
-                       bool to_bottom = (i == 0);
-
-                       // If liquid is at lowest possible height, it's not going
-                       // anywhere except down
-                       if(liquid_level == 0 && to_bottom == false)
-                               continue;
-
-                       u8 liquid_next_level = 0;
-                       // If going to bottom
-                       if(to_bottom)
-                       {
-                               //liquid_next_level = 7;
-                               if(liquid_level >= 7 - WATER_DROP_BOOST)
-                                       liquid_next_level = 7;
-                               else
-                                       liquid_next_level = liquid_level + WATER_DROP_BOOST;
-                       }
-                       else
-                               liquid_next_level = liquid_level - 1;
-
-                       bool n2_changed = false;
-                       bool flowed = false;
-
-                       v3s16 p2 = p0 + dirs_to[i];
-
-                       MapNode n2 = getNodeNoEx(p2);
-                       //dstream<<"[1] n2.param="<<(int)n2.param<<std::endl;
-
-                       if(content_liquid(n2.getContent()))
-                       {
-                               u8 n2_nonsource_c = make_liquid_flowing(n2.getContent());
-                               // Check that the liquids are the same type
-                               if(n2_nonsource_c != nonsource_c)
-                               {
-                                       dstream<<"WARNING: Not handling: different liquids"
-                                                       " collide"<<std::endl;
-                                       continue;
+                       decide on the type (and possibly level) of the current node
+                */
+               content_t new_node_content;
+               s8 new_node_level = -1;
+               if (num_sources >= 2 || liquid_type == LIQUID_SOURCE) {
+                       // liquid_kind will be set to either the flowing alternative of the node (if it's a liquid)
+                       // or the flowing alternative of the first of the surrounding sources (if it's air), so
+                       // it's perfectly safe to use liquid_kind here to determine the new node content.
+                       new_node_content = content_features(liquid_kind).liquid_alternative_source;
+               } else if (num_sources == 1 && sources[0].t != NEIGHBOR_LOWER) {
+                       // liquid_kind is set properly, see above
+                       new_node_content = liquid_kind;
+                       new_node_level = 7;
+               } else {
+                       // no surrounding sources, so get the maximum level that can flow into this node
+                       for (u16 i = 0; i < num_flows; i++) {
+                               u8 nb_liquid_level = (flows[i].n.param2 & LIQUID_LEVEL_MASK);
+                               switch (flows[i].t) {
+                                       case NEIGHBOR_UPPER:
+                                               if (nb_liquid_level + WATER_DROP_BOOST > new_node_level) {
+                                                       new_node_level = 7;
+                                                       if (nb_liquid_level + WATER_DROP_BOOST < 7)
+                                                               new_node_level = nb_liquid_level + WATER_DROP_BOOST;
+                                               }
+                                               break;
+                                       case NEIGHBOR_LOWER:
+                                               break;
+                                       case NEIGHBOR_SAME_LEVEL:
+                                               if ((flows[i].n.param2 & LIQUID_FLOW_DOWN_MASK) != LIQUID_FLOW_DOWN_MASK &&
+                                                       nb_liquid_level > 0 && nb_liquid_level - 1 > new_node_level) {
+                                                       new_node_level = nb_liquid_level - 1;
+                                               }
+                                               break;
                                }
-                               bool n2_is_source = !content_flowing_liquid(n2.getContent());
-                               u8 n2_liquid_level = 8;
-                               if(n2_is_source == false)
-                                       n2_liquid_level = n2.param2 & 0x07;
-
-                               if(to_bottom)
-                               {
-                                       flowed = true;
-                               }
-
-                               if(n2_is_source)
-                               {
-                                       // Just flow into the source, nothing changes.
-                                       // n2_changed is not set because destination didn't change
-                                       flowed = true;
-                               }
-                               else
-                               {
-                                       if(liquid_next_level > liquid_level)
-                                       {
-                                               n2.param2 = liquid_next_level;
-                                               setNode(p2, n2);
-
-                                               n2_changed = true;
-                                               flowed = true;
+                       }
+                       // don't flow as far in open terrain - if there isn't at least one adjacent solid block,
+                       // substract another unit from the resulting water level.
+                       if (!flowing_down && new_node_level >= 1) {
+                               bool at_wall = false;
+                               for (u16 i = 0; i < num_neutrals; i++) {
+                                       if (neutrals[i].t == NEIGHBOR_SAME_LEVEL) {
+                                               at_wall = true;
+                                               break;
                                        }
                                }
+                               if (!at_wall)
+                                       new_node_level -= 1;
                        }
-                       else if(n2.getContent() == CONTENT_AIR)
-                       {
-                               n2.setContent(nonsource_c);
-                               n2.param2 = liquid_next_level;
-                               setNode(p2, n2);
 
-                               n2_changed = true;
-                               flowed = true;
-                       }
+                       if (new_node_level >= 0)
+                               new_node_content = liquid_kind;
+                       else
+                               new_node_content = CONTENT_AIR;
+               }
 
-                       //dstream<<"[2] n2.param="<<(int)n2.param<<std::endl;
+               /*
+                       check if anything has changed. if not, just continue with the next node.
+                */
+               if (new_node_content == n0.getContent() && (content_features(n0.getContent()).liquid_type != LIQUID_FLOWING ||
+                                                                                ((n0.param2 & LIQUID_LEVEL_MASK) == (u8)new_node_level &&
+                                                                                ((n0.param2 & LIQUID_FLOW_DOWN_MASK) == LIQUID_FLOW_DOWN_MASK)
+                                                                                == flowing_down)))
+                       continue;
 
-                       if(n2_changed)
-                       {
-                               m_transforming_liquid.push_back(p2);
 
-                               v3s16 blockpos = getNodeBlockPos(p2);
-                               MapBlock *block = getBlockNoCreateNoEx(blockpos);
-                               if(block != NULL)
-                                       modified_blocks.insert(blockpos, block);
-                       }
+               /*
+                       update the current node
+                */
+               bool flow_down_enabled = (flowing_down && ((n0.param2 & LIQUID_FLOW_DOWN_MASK) != LIQUID_FLOW_DOWN_MASK));
+               n0.setContent(new_node_content);
+               if (content_features(n0.getContent()).liquid_type == LIQUID_FLOWING) {
+                       // set level to last 3 bits, flowing down bit to 4th bit
+                       n0.param2 |= (flowing_down ? LIQUID_FLOW_DOWN_MASK : 0x00) | (new_node_level & LIQUID_LEVEL_MASK);
+               } else {
+                       // set the liquid level and flow bit to 0
+                       n0.param2 &= ~(LIQUID_LEVEL_MASK | LIQUID_FLOW_DOWN_MASK);
+               }
+               setNode(p0, n0);
+               v3s16 blockpos = getNodeBlockPos(p0);
+               MapBlock *block = getBlockNoCreateNoEx(blockpos);
+               if(block != NULL)
+                       modified_blocks.insert(blockpos, block);
 
-                       // If n2_changed to bottom, don't flow anywhere else
-                       if(to_bottom && flowed && !is_source)
+               /*
+                       enqueue neighbors for update if neccessary
+                */
+               switch (content_features(n0.getContent()).liquid_type) {
+                       case LIQUID_SOURCE:
+                               // make sure source flows into all neighboring nodes
+                               for (u16 i = 0; i < num_flows; i++)
+                                       if (flows[i].t != NEIGHBOR_UPPER)
+                                               m_transforming_liquid.push_back(flows[i].p);
+                               for (u16 i = 0; i < num_airs; i++)
+                                       if (airs[i].t != NEIGHBOR_UPPER)
+                                               m_transforming_liquid.push_back(airs[i].p);
+                               break;
+                       case LIQUID_NONE:
+                               // this flow has turned to air; neighboring flows might need to do the same
+                               for (u16 i = 0; i < num_flows; i++)
+                                       m_transforming_liquid.push_back(flows[i].p);
+                               break;
+                       case LIQUID_FLOWING:
+                               for (u16 i = 0; i < num_flows; i++) {
+                                       u8 flow_level = (flows[i].n.param2 & LIQUID_LEVEL_MASK);
+                                       // liquid_level is still the ORIGINAL level of this node.
+                                       if (flows[i].t != NEIGHBOR_UPPER && ((flow_level < liquid_level || flow_level < new_node_level) ||
+                                               flow_down_enabled))
+                                               m_transforming_liquid.push_back(flows[i].p);
+                               }
+                               for (u16 i = 0; i < num_airs; i++) {
+                                       if (airs[i].t != NEIGHBOR_UPPER && (airs[i].t == NEIGHBOR_LOWER || new_node_level > 0))
+                                               m_transforming_liquid.push_back(airs[i].p);
+                               }
                                break;
                }
-
-               loopcount++;
-               //if(loopcount >= 100000)
-               if(loopcount >= initial_size * 1)
-                       break;
        }
        //dstream<<"Map::transformLiquids(): loopcount="<<loopcount<<std::endl;
 }
@@ -2012,8 +1996,10 @@ ServerMap::~ServerMap()
 
 void ServerMap::initBlockMake(mapgen::BlockMakeData *data, v3s16 blockpos)
 {
-       /*dstream<<"initBlockMake(): ("<<blockpos.X<<","<<blockpos.Y<<","
-                       <<blockpos.Z<<")"<<std::endl;*/
+       bool enable_mapgen_debug_info = g_settings.getBool("enable_mapgen_debug_info");
+       if(enable_mapgen_debug_info)
+               dstream<<"initBlockMake(): ("<<blockpos.X<<","<<blockpos.Y<<","
+                               <<blockpos.Z<<")"<<std::endl;
        
        // Do nothing if not inside limits (+-1 because of neighbors)
        if(blockpos_over_limit(blockpos - v3s16(1,1,1)) ||
@@ -2043,25 +2029,28 @@ void ServerMap::initBlockMake(mapgen::BlockMakeData *data, v3s16 blockpos)
 
                        for(s16 y=-1; y<=1; y++)
                        {
-                               //MapBlock *block = createBlock(blockpos);
+                               v3s16 p(blockpos.X+x, blockpos.Y+y, blockpos.Z+z);
+                               //MapBlock *block = createBlock(p);
                                // 1) get from memory, 2) load from disk
-                               MapBlock *block = emergeBlock(blockpos, false);
+                               MapBlock *block = emergeBlock(p, false);
                                // 3) create a blank one
                                if(block == NULL)
-                                       block = createBlock(blockpos);
+                               {
+                                       block = createBlock(p);
+
+                                       /*
+                                               Block gets sunlight if this is true.
+
+                                               Refer to the map generator heuristics.
+                                       */
+                                       bool ug = mapgen::block_is_underground(data->seed, p);
+                                       block->setIsUnderground(ug);
+                               }
 
                                // Lighting will not be valid after make_chunk is called
                                block->setLightingExpired(true);
                                // Lighting will be calculated
                                //block->setLightingExpired(false);
-
-                               /*
-                                       Block gets sunlight if this is true.
-
-                                       This should be set to true when the top side of a block
-                                       is completely exposed to the sky.
-                               */
-                               block->setIsUnderground(false);
                        }
                }
        }
@@ -2137,10 +2126,14 @@ MapBlock* ServerMap::finishBlockMake(mapgen::BlockMakeData *data,
        assert(block);
 
        /*
-               Set is_underground flag for lighting with sunlight
+               Set is_underground flag for lighting with sunlight.
+
+               Refer to map generator heuristics.
+
+               NOTE: This is done in initChunkMake
        */
+       //block->setIsUnderground(mapgen::block_is_underground(data->seed, blockpos));
 
-       block->setIsUnderground(mapgen::block_is_underground(data->seed, blockpos));
 
        /*
                Add sunlight to central block.
@@ -2171,6 +2164,13 @@ MapBlock* ServerMap::finishBlockMake(mapgen::BlockMakeData *data,
 #if 1
                // Center block
                lighting_update_blocks.insert(block->getPos(), block);
+
+               /*{
+                       s16 x = 0;
+                       s16 z = 0;
+                       v3s16 p = block->getPos()+v3s16(x,1,z);
+                       lighting_update_blocks[p] = getBlockNoCreateNoEx(p);
+               }*/
 #endif
 #if 0
                // All modified blocks
@@ -2187,8 +2187,28 @@ MapBlock* ServerMap::finishBlockMake(mapgen::BlockMakeData *data,
                        lighting_update_blocks.insert(i.getNode()->getKey(),
                                        i.getNode()->getValue());
                }
+               /*// Also force-add all the upmost blocks for proper sunlight
+               for(s16 x=-1; x<=1; x++)
+               for(s16 z=-1; z<=1; z++)
+               {
+                       v3s16 p = block->getPos()+v3s16(x,1,z);
+                       lighting_update_blocks[p] = getBlockNoCreateNoEx(p);
+               }*/
 #endif
                updateLighting(lighting_update_blocks, changed_blocks);
+               
+               /*
+                       Set lighting to non-expired state in all of them.
+                       This is cheating, but it is not fast enough if all of them
+                       would actually be updated.
+               */
+               for(s16 x=-1; x<=1; x++)
+               for(s16 y=-1; y<=1; y++)
+               for(s16 z=-1; z<=1; z++)
+               {
+                       v3s16 p = block->getPos()+v3s16(x,y,z);
+                       getBlockNoCreateNoEx(p)->setLightingExpired(false);
+               }
 
                if(enable_mapgen_debug_info == false)
                        t.stop(true); // Hide output
@@ -2230,7 +2250,26 @@ MapBlock* ServerMap::finishBlockMake(mapgen::BlockMakeData *data,
 
        /*dstream<<"finishBlockMake() done for ("<<blockpos.X<<","<<blockpos.Y<<","
                        <<blockpos.Z<<")"<<std::endl;*/
-       
+#if 0
+       if(enable_mapgen_debug_info)
+       {
+               /*
+                       Analyze resulting blocks
+               */
+               for(s16 x=-1; x<=1; x++)
+               for(s16 y=-1; y<=1; y++)
+               for(s16 z=-1; z<=1; z++)
+               {
+                       v3s16 p = block->getPos()+v3s16(x,y,z);
+                       MapBlock *block = getBlockNoCreateNoEx(p);
+                       char spos[20];
+                       snprintf(spos, 20, "(%2d,%2d,%2d)", x, y, z);
+                       dstream<<"Generated "<<spos<<": "
+                                       <<analyze_block(block)<<std::endl;
+               }
+       }
+#endif
+
        return block;
 }
 
@@ -2479,7 +2518,7 @@ MapBlock * ServerMap::emergeBlock(v3s16 p, bool allow_generate)
        
        {
                MapBlock *block = getBlockNoCreateNoEx(p);
-               if(block)
+               if(block && block->isDummy() == false)
                        return block;
        }
 
@@ -4081,10 +4120,16 @@ void ManualMapVoxelManipulator::blitBackAll(
                        i = m_loaded_blocks.getIterator();
                        i.atEnd() == false; i++)
        {
+               v3s16 p = i.getNode()->getKey();
                bool existed = i.getNode()->getValue();
                if(existed == false)
+               {
+                       // The Great Bug was found using this
+                       /*dstream<<"ManualMapVoxelManipulator::blitBackAll: "
+                                       <<"Inexistent ("<<p.X<<","<<p.Y<<","<<p.Z<<")"
+                                       <<std::endl;*/
                        continue;
-               v3s16 p = i.getNode()->getKey();
+               }
                MapBlock *block = m_map->getBlockNoCreateNoEx(p);
                if(block == NULL)
                {