8x block meshes (#13133)

Reduce the number of drawcalls by generating a mesh per 8 blocks (2x2x2). Only blocks with even coordinates (lowest bit set to 0) will get a mesh.

Note: This also removes the old 'loops' algorithm for building the draw list, because it produces visual artifacts and cannot be made compatible with the approach of having a mesh for every 8th block without hurting performance.

Co-authored-by: Jude Melton-Houghton <jwmhjwmh@gmail.com>
Co-authored-by: Lars <larsh@apache.org>
Co-authored-by: sfan5 <sfan5@live.de>

src/client/client.cpp

@@ -41,6 +41,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "filesys.h"
 #include "mapblock_mesh.h"
 #include "mapblock.h"
+#include "mapsector.h"
 #include "minimap.h"
 #include "modchannels.h"
 #include "content/mods.h"
@@ -555,19 +556,27 @@ void Client::step(float dtime)
 		{
 			num_processed_meshes++;
 
-			MinimapMapblock *minimap_mapblock = NULL;
+			std::vector<MinimapMapblock*> minimap_mapblocks;
 			bool do_mapper_update = true;
 
-			MapBlock *block = m_env.getMap().getBlockNoCreateNoEx(r.p);
+			MapSector *sector = m_env.getMap().emergeSector(v2s16(r.p.X, r.p.Z));
+
+			MapBlock *block = sector->getBlockNoCreateNoEx(r.p.Y);
+
+			// The block in question is not visible (perhaps it is culled at the server),
+			// create a blank block just to hold the 2x2x2 mesh.
+			// If the block becomes visible later it will replace the blank block.
+			if (!block && r.mesh)
+				block = sector->createBlankBlock(r.p.Y);
+
 			if (block) {
 				// Delete the old mesh
 				delete block->mesh;
 				block->mesh = nullptr;
 
 				if (r.mesh) {
-					block->solid_sides = r.solid_sides;
+					minimap_mapblocks = r.mesh->moveMinimapMapblocks();
-					minimap_mapblock = r.mesh->moveMinimapMapblock();
+					if (minimap_mapblocks.empty())
-					if (minimap_mapblock == NULL)
 						do_mapper_update = false;
 
 					bool is_empty = true;
@@ -588,16 +597,32 @@ void Client::step(float dtime)
 				delete r.mesh;
 			}
 
-			if (m_minimap && do_mapper_update)
+			for (auto p : r.solid_sides) {
-				m_minimap->addBlock(r.p, minimap_mapblock);
+				auto block = m_env.getMap().getBlockNoCreateNoEx(p.first);
+				if (block)
+					block->solid_sides = p.second;
+			}
 
-			if (r.ack_block_to_server) {
+			if (m_minimap && do_mapper_update) {
+				v3s16 ofs;
+
+				// See also mapblock_mesh.cpp for the code that creates the array of minimap blocks.
+				for (ofs.Z = 0; ofs.Z <= 1; ofs.Z++)
+				for (ofs.Y = 0; ofs.Y <= 1; ofs.Y++)
+				for (ofs.X = 0; ofs.X <= 1; ofs.X++) {
+					size_t i = ofs.Z * 4 + ofs.Y * 2 + ofs.X;
+					if (i < minimap_mapblocks.size() && minimap_mapblocks[i])
+						m_minimap->addBlock(r.p + ofs, minimap_mapblocks[i]);
+				}
+			}
+
+			for (auto p : r.ack_list) {
 				if (blocks_to_ack.size() == 255) {
 					sendGotBlocks(blocks_to_ack);
 					blocks_to_ack.clear();
 				}
 
-				blocks_to_ack.emplace_back(r.p);
+				blocks_to_ack.emplace_back(p);
 			}
 
 			for (auto block : r.map_blocks)

src/client/clientmap.cpp

@@ -298,6 +298,8 @@ void ClientMap::updateDrawList()
 	blocks_to_consider.push(camera_block);
 	blocks_seen.getChunk(camera_block).getBits(camera_block) = 0x07; // mark all sides as visible
 
+	std::set<v3s16> shortlist;
+
 	// Recursively walk the space and pick mapblocks for drawing
 	while (blocks_to_consider.size() > 0) {
 
@@ -369,11 +371,13 @@ void ClientMap::updateDrawList()
 			continue;
 		}
 
-		// The block is visible, add to the draw list
+		// Block meshes are stored in blocks where all coordinates are even (lowest bit set to 0)
-		if (mesh) {
+		// Add them to the de-dup set.
-			// Add to set
+		shortlist.emplace(block_coord.X & ~1, block_coord.Y & ~1, block_coord.Z & ~1);
+		// All other blocks we can grab and add to the drawlist right away.
+		if (block && m_drawlist.emplace(block_coord, block).second) {
+			// only grab the ref if the block exists and was not in the list
 			block->refGrab();
-			m_drawlist[block_coord] = block;
 		}
 
 		// Decide which sides to traverse next or to block away
@@ -474,6 +478,16 @@ void ClientMap::updateDrawList()
 		}
 	}
 
+	g_profiler->avg("MapBlocks shortlist [#]", shortlist.size());
+
+	for (auto pos : shortlist) {
+		MapBlock * block = getBlockNoCreateNoEx(pos);
+		if (block && m_drawlist.emplace(pos, block).second) {
+			// only grab the ref if the block exists and was not in the list
+			block->refGrab();
+		}
+	}
+
 	g_profiler->avg("MapBlocks occlusion culled [#]", blocks_occlusion_culled);
 	g_profiler->avg("MapBlocks sides skipped [#]", sides_skipped);
 	g_profiler->avg("MapBlocks examined [#]", blocks_visited);
@@ -597,7 +611,11 @@ void ClientMap::renderMap(video::IVideoDriver* driver, s32 pass)
 		MapBlock *block = i.second;
 		MapBlockMesh *block_mesh = block->mesh;
 
-		// If the mesh of the block happened to get deleted, ignore it
+		// Meshes are only stored every 8-th block (where all coordinates are even),
+		// but we keep all the visible blocks in the draw list to prevent client
+		// from dropping them.
+		// On top of that, in some cases block mesh can be removed
+		// before the block is removed from the draw list.
 		if (!block_mesh)
 			continue;
 
@@ -720,7 +738,7 @@ void ClientMap::renderMap(video::IVideoDriver* driver, s32 pass)
 			material.TextureLayer[ShadowRenderer::TEXTURE_LAYER_SHADOW].Texture = nullptr;
 		}
 
-		v3f block_wpos = intToFloat(descriptor.m_pos * MAP_BLOCKSIZE, BS);
+		v3f block_wpos = intToFloat(descriptor.m_pos / 8 * 8 * MAP_BLOCKSIZE, BS);
 		m.setTranslation(block_wpos - offset);
 
 		driver->setTransform(video::ETS_WORLD, m);
@@ -1046,7 +1064,7 @@ void ClientMap::renderMapShadows(video::IVideoDriver *driver,
 			++material_swaps;
 		}
 
-		v3f block_wpos = intToFloat(descriptor.m_pos * MAP_BLOCKSIZE, BS);
+		v3f block_wpos = intToFloat(descriptor.m_pos / 8 * 8 * MAP_BLOCKSIZE, BS);
 		m.setTranslation(block_wpos - offset);
 
 		driver->setTransform(video::ETS_WORLD, m);
@@ -1133,6 +1151,11 @@ void ClientMap::updateDrawListShadow(v3f shadow_light_pos, v3f shadow_light_dir,
 	g_profiler->avg("SHADOW MapBlocks loaded [#]", blocks_loaded);
 }
 
+void ClientMap::reportMetrics(u64 save_time_us, u32 saved_blocks, u32 all_blocks)
+{
+	g_profiler->avg("CM::reportMetrics loaded blocks [#]", all_blocks);
+}
+
 void ClientMap::updateTransparentMeshBuffers()
 {
 	ScopeProfiler sp(g_profiler, "CM::updateTransparentMeshBuffers", SPT_AVG);

src/client/clientmap.h

@@ -140,6 +140,8 @@ public:
 
 	void onSettingChanged(const std::string &name);
 
+protected:
+	void reportMetrics(u64 save_time_us, u32 saved_blocks, u32 all_blocks) override;
 private:
 
 	// update the vertex order in transparent mesh buffers

src/client/content_mapblock.cpp

@@ -1619,9 +1619,9 @@ void MapblockMeshGenerator::drawNode()
 */
 void MapblockMeshGenerator::generate()
 {
-	for (p.Z = 0; p.Z < MAP_BLOCKSIZE; p.Z++)
+	for (p.Z = 0; p.Z < data->side_length; p.Z++)
-	for (p.Y = 0; p.Y < MAP_BLOCKSIZE; p.Y++)
+	for (p.Y = 0; p.Y < data->side_length; p.Y++)
-	for (p.X = 0; p.X < MAP_BLOCKSIZE; p.X++) {
+	for (p.X = 0; p.X < data->side_length; p.X++) {
 		n = data->m_vmanip.getNodeNoEx(blockpos_nodes + p);
 		f = &nodedef->get(n);
 		drawNode();

src/client/mapblock_mesh.cpp

@@ -49,7 +49,7 @@ void MeshMakeData::fillBlockDataBegin(const v3s16 &blockpos)
 
 	m_vmanip.clear();
 	VoxelArea voxel_area(blockpos_nodes - v3s16(1,1,1) * MAP_BLOCKSIZE,
-			blockpos_nodes + v3s16(1,1,1) * MAP_BLOCKSIZE*2-v3s16(1,1,1));
+			blockpos_nodes + v3s16(1,1,1) * (side_length + MAP_BLOCKSIZE /* extra layer of blocks around the mesh */) - v3s16(1,1,1));
 	m_vmanip.addArea(voxel_area);
 }
 
@@ -63,23 +63,6 @@ void MeshMakeData::fillBlockData(const v3s16 &block_offset, MapNode *data)
 	m_vmanip.copyFrom(data, data_area, v3s16(0,0,0), blockpos_nodes, data_size);
 }
 
-void MeshMakeData::fill(MapBlock *block)
-{
-	fillBlockDataBegin(block->getPos());
-
-	fillBlockData(v3s16(0,0,0), block->getData());
-
-	// Get map for reading neighbor blocks
-	Map *map = block->getParent();
-
-	for (const v3s16 &dir : g_26dirs) {
-		v3s16 bp = m_blockpos + dir;
-		MapBlock *b = map->getBlockNoCreateNoEx(bp);
-		if(b)
-			fillBlockData(dir, b->getData());
-	}
-}
-
 void MeshMakeData::setCrack(int crack_level, v3s16 crack_pos)
 {
 	if (crack_level >= 0)
@@ -883,7 +866,7 @@ static void updateFastFaceRow(
 
 	// Unroll this variable which has a significant build cost
 	TileSpec next_tile;
-	for (u16 j = 0; j < MAP_BLOCKSIZE; j++) {
+	for (u16 j = 0; j < data->side_length; j++) {
 		// If tiling can be done, this is set to false in the next step
 		bool next_is_different = true;
 
@@ -894,7 +877,7 @@ static void updateFastFaceRow(
 
 		// If at last position, there is nothing to compare to and
 		// the face must be drawn anyway
-		if (j != MAP_BLOCKSIZE - 1) {
+		if (j != data->side_length - 1) {
 			p += translate_dir;
 
 			getTileInfo(data, p, face_dir,
@@ -957,8 +940,8 @@ static void updateAllFastFaceRows(MeshMakeData *data,
 	/*
 		Go through every y,z and get top(y+) faces in rows of x+
 	*/
-	for (s16 y = 0; y < MAP_BLOCKSIZE; y++)
+	for (s16 y = 0; y < data->side_length; y++)
-	for (s16 z = 0; z < MAP_BLOCKSIZE; z++)
+	for (s16 z = 0; z < data->side_length; z++)
 		updateFastFaceRow(data,
 				v3s16(0, y, z),
 				v3s16(1, 0, 0), //dir
@@ -969,8 +952,8 @@ static void updateAllFastFaceRows(MeshMakeData *data,
 	/*
 		Go through every x,y and get right(x+) faces in rows of z+
 	*/
-	for (s16 x = 0; x < MAP_BLOCKSIZE; x++)
+	for (s16 x = 0; x < data->side_length; x++)
-	for (s16 y = 0; y < MAP_BLOCKSIZE; y++)
+	for (s16 y = 0; y < data->side_length; y++)
 		updateFastFaceRow(data,
 				v3s16(x, y, 0),
 				v3s16(0, 0, 1), //dir
@@ -981,8 +964,8 @@ static void updateAllFastFaceRows(MeshMakeData *data,
 	/*
 		Go through every y,z and get back(z+) faces in rows of x+
 	*/
-	for (s16 z = 0; z < MAP_BLOCKSIZE; z++)
+	for (s16 z = 0; z < data->side_length; z++)
-	for (s16 y = 0; y < MAP_BLOCKSIZE; y++)
+	for (s16 y = 0; y < data->side_length; y++)
 		updateFastFaceRow(data,
 				v3s16(0, y, z),
 				v3s16(1, 0, 0), //dir
@@ -1009,7 +992,7 @@ static void applyTileColor(PreMeshBuffer &pmb)
 	MapBlockBspTree
 */
 
-void MapBlockBspTree::buildTree(const std::vector<MeshTriangle> *triangles)
+void MapBlockBspTree::buildTree(const std::vector<MeshTriangle> *triangles, u16 side_length)
 {
 	this->triangles = triangles;
 
@@ -1024,7 +1007,7 @@ void MapBlockBspTree::buildTree(const std::vector<MeshTriangle> *triangles)
 
 	if (!indexes.empty()) {
 		// Start in the center of the block with increment of one quarter in each direction
-		root = buildTree(v3f(1, 0, 0), v3f((MAP_BLOCKSIZE + 1) * 0.5f * BS), MAP_BLOCKSIZE * 0.25f * BS, indexes, 0);
+		root = buildTree(v3f(1, 0, 0), v3f((side_length + 1) * 0.5f * BS), side_length * 0.25f * BS, indexes, 0);
 	} else {
 		root = -1;
 	}
@@ -1183,7 +1166,6 @@ void PartialMeshBuffer::afterDraw() const
 */
 
 MapBlockMesh::MapBlockMesh(MeshMakeData *data, v3s16 camera_offset):
-	m_minimap_mapblock(NULL),
 	m_tsrc(data->m_client->getTextureSource()),
 	m_shdrsrc(data->m_client->getShaderSource()),
 	m_animation_force_timer(0), // force initial animation
@@ -1195,10 +1177,23 @@ MapBlockMesh::MapBlockMesh(MeshMakeData *data, v3s16 camera_offset):
 	m_enable_shaders = data->m_use_shaders;
 	m_enable_vbo = g_settings->getBool("enable_vbo");
 
-	if (data->m_client->getMinimap()) {
+	v3s16 bp = data->m_blockpos;
-		m_minimap_mapblock = new MinimapMapblock;
+	// Only generate minimap mapblocks at even coordinates.
-		m_minimap_mapblock->getMinimapNodes(
+	if (((bp.X | bp.Y | bp.Z) & 1) == 0 && data->m_client->getMinimap()) {
-			&data->m_vmanip, data->m_blockpos * MAP_BLOCKSIZE);
+		m_minimap_mapblocks.resize(8, nullptr);
+		v3s16 ofs;
+
+		// See also client.cpp for the code that reads the array of minimap blocks.
+		for (ofs.Z = 0; ofs.Z <= 1; ofs.Z++)
+		for (ofs.Y = 0; ofs.Y <= 1; ofs.Y++)
+		for (ofs.X = 0; ofs.X <= 1; ofs.X++) {
+			v3s16 p = (bp + ofs) * MAP_BLOCKSIZE;
+			if (data->m_vmanip.getNodeNoEx(p).getContent() != CONTENT_IGNORE) {
+				MinimapMapblock *block = new MinimapMapblock;
+				m_minimap_mapblocks[ofs.Z * 4 + ofs.Y * 2 + ofs.X] = block;
+				block->getMinimapNodes(&data->m_vmanip, p);
+			}
+		}
 	}
 
 	// 4-21ms for MAP_BLOCKSIZE=16  (NOTE: probably outdated)
@@ -1226,7 +1221,8 @@ MapBlockMesh::MapBlockMesh(MeshMakeData *data, v3s16 camera_offset):
 		Convert FastFaces to MeshCollector
 	*/
 
-	MeshCollector collector(m_bounding_sphere_center);
+	v3f offset = intToFloat((data->m_blockpos - data->m_blockpos / 8 * 8) * MAP_BLOCKSIZE, BS);
+	MeshCollector collector(m_bounding_sphere_center, offset);
 
 	{
 		// avg 0ms (100ms spikes when loading textures the first time)
@@ -1386,7 +1382,7 @@ MapBlockMesh::MapBlockMesh(MeshMakeData *data, v3s16 camera_offset):
 	}
 
 	//std::cout<<"added "<<fastfaces.getSize()<<" faces."<<std::endl;
-	m_bsp_tree.buildTree(&m_transparent_triangles);
+	m_bsp_tree.buildTree(&m_transparent_triangles, data->side_length);
 
 	// Check if animation is required for this mesh
 	m_has_animation =
@@ -1408,7 +1404,8 @@ MapBlockMesh::~MapBlockMesh()
 #endif
 		m->drop();
 	}
-	delete m_minimap_mapblock;
+	for (MinimapMapblock *block : m_minimap_mapblocks)
+		delete block;
 }
 
 bool MapBlockMesh::animate(bool faraway, float time, int crack,
@@ -1583,30 +1580,39 @@ video::SColor encode_light(u16 light, u8 emissive_light)
 	return video::SColor(r, b, b, b);
 }
 
-u8 get_solid_sides(MeshMakeData *data)
+std::unordered_map<v3s16, u8> get_solid_sides(MeshMakeData *data)
 {
-	v3s16 blockpos_nodes = data->m_blockpos * MAP_BLOCKSIZE;
+	std::unordered_map<v3s16, u8> results;
-	const NodeDefManager *ndef = data->m_client->ndef();
+	v3s16 ofs;
 
-	u8 result = 0x3F; // all sides solid;
+	for (ofs.X = 0; ofs.X < 2; ofs.X++)
+	for (ofs.Y = 0; ofs.Y < 2; ofs.Y++)
+	for (ofs.Z = 0; ofs.Z < 2; ofs.Z++) {
+		v3s16 blockpos = data->m_blockpos + ofs;
+		v3s16 blockpos_nodes = blockpos * MAP_BLOCKSIZE;
+		const NodeDefManager *ndef = data->m_client->ndef();
 
-	for (s16 i = 0; i < MAP_BLOCKSIZE && result != 0; i++)
+		u8 result = 0x3F; // all sides solid;
-	for (s16 j = 0; j < MAP_BLOCKSIZE && result != 0; j++) {
-		v3s16 positions[6] = {
-			v3s16(0, i, j),
-			v3s16(MAP_BLOCKSIZE - 1, i, j),
-			v3s16(i, 0, j),
-			v3s16(i, MAP_BLOCKSIZE - 1, j),
-			v3s16(i, j, 0),
-			v3s16(i, j, MAP_BLOCKSIZE - 1)
-		};
 
-		for (u8 k = 0; k < 6; k++) {
+		for (s16 i = 0; i < MAP_BLOCKSIZE && result != 0; i++)
-			const MapNode &top = data->m_vmanip.getNodeRefUnsafe(blockpos_nodes + positions[k]);
+		for (s16 j = 0; j < MAP_BLOCKSIZE && result != 0; j++) {
-			if (ndef->get(top).solidness != 2)
+			v3s16 positions[6] = {
-				result &= ~(1 << k);
+				v3s16(0, i, j),
+				v3s16(MAP_BLOCKSIZE - 1, i, j),
+				v3s16(i, 0, j),
+				v3s16(i, MAP_BLOCKSIZE - 1, j),
+				v3s16(i, j, 0),
+				v3s16(i, j, MAP_BLOCKSIZE - 1)
+			};
+
+			for (u8 k = 0; k < 6; k++) {
+				const MapNode &top = data->m_vmanip.getNodeRefUnsafe(blockpos_nodes + positions[k]);
+				if (ndef->get(top).solidness != 2)
+					result &= ~(1 << k);
+			}
 		}
-	}
 
-	return result;
+		results[blockpos] = result;
+	}
+	return results;
 }

src/client/mapblock_mesh.h

@@ -24,6 +24,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "voxel.h"
 #include <array>
 #include <map>
+#include <unordered_map>
 
 class Client;
 class IShaderSource;
@@ -42,6 +43,7 @@ struct MeshMakeData
 	v3s16 m_blockpos = v3s16(-1337,-1337,-1337);
 	v3s16 m_crack_pos_relative = v3s16(-1337,-1337,-1337);
 	bool m_smooth_lighting = false;
+	u16 side_length = MAP_BLOCKSIZE;
 
 	Client *m_client;
 	bool m_use_shaders;
@@ -54,12 +56,6 @@ struct MeshMakeData
 	void fillBlockDataBegin(const v3s16 &blockpos);
 	void fillBlockData(const v3s16 &block_offset, MapNode *data);
 
-	/*
-		Copy central data directly from block, and other data from
-		parent of block.
-	*/
-	void fill(MapBlock *block);
-
 	/*
 		Set the (node) position of a crack
 	*/
@@ -108,7 +104,7 @@ class MapBlockBspTree
 public:
 	MapBlockBspTree() {}
 
-	void buildTree(const std::vector<MeshTriangle> *triangles);
+	void buildTree(const std::vector<MeshTriangle> *triangles, u16 side_lingth);
 
 	void traverse(v3f viewpoint, std::vector<s32> &output) const
 	{
@@ -203,11 +199,11 @@ public:
 		return m_mesh[layer];
 	}
 
-	MinimapMapblock *moveMinimapMapblock()
+	std::vector<MinimapMapblock*> moveMinimapMapblocks()
 	{
-		MinimapMapblock *p = m_minimap_mapblock;
+		std::vector<MinimapMapblock*> minimap_mapblocks;
-		m_minimap_mapblock = NULL;
+		minimap_mapblocks.swap(m_minimap_mapblocks);
-		return p;
+		return minimap_mapblocks;
 	}
 
 	bool isAnimationForced() const
@@ -245,7 +241,7 @@ private:
 	};
 
 	scene::IMesh *m_mesh[MAX_TILE_LAYERS];
-	MinimapMapblock *m_minimap_mapblock;
+	std::vector<MinimapMapblock*> m_minimap_mapblocks;
 	ITextureSource *m_tsrc;
 	IShaderSource *m_shdrsrc;
 
@@ -344,4 +340,4 @@ void getNodeTile(MapNode mn, const v3s16 &p, const v3s16 &dir, MeshMakeData *dat
 /// Return bitset of the sides of the mapblock that consist of solid nodes only
 /// Bits:
 /// 0 0 -Z +Z -X +X -Y +Y
-u8 get_solid_sides(MeshMakeData *data);
+std::unordered_map<v3s16, u8> get_solid_sides(MeshMakeData *data);

src/client/mesh_generator_thread.cpp

@@ -25,6 +25,17 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "map.h"
 #include "util/directiontables.h"
 
+static class BlockPlaceholder {
+public:
+	MapNode data[MAP_BLOCKSIZE * MAP_BLOCKSIZE * MAP_BLOCKSIZE];
+
+	BlockPlaceholder()
+	{
+		for (std::size_t i = 0; i < MAP_BLOCKSIZE * MAP_BLOCKSIZE * MAP_BLOCKSIZE; i++)
+			data[i] = MapNode(CONTENT_IGNORE);
+	}
+
+} block_placeholder;
 /*
 	QueuedMeshUpdate
 */
@@ -66,28 +77,31 @@ bool MeshUpdateQueue::addBlock(Map *map, v3s16 p, bool ack_block_to_server, bool
 
 	MutexAutoLock lock(m_mutex);
 
+	// Mesh is placed at even positions at all coordinates
+	// (every 8-th block) and will cover 8 blocks
+	v3s16 mesh_position(p.X & ~1, p.Y & ~1, p.Z & ~1);
 	/*
 		Mark the block as urgent if requested
 	*/
 	if (urgent)
-		m_urgents.insert(p);
+		m_urgents.insert(mesh_position);
 
 	/*
 		Find if block is already in queue.
 		If it is, update the data and quit.
 	*/
 	for (QueuedMeshUpdate *q : m_queue) {
-		if (q->p == p) {
+		if (q->p == mesh_position) {
 			// NOTE: We are not adding a new position to the queue, thus
 			//       refcount_from_queue stays the same.
 			if(ack_block_to_server)
-				q->ack_block_to_server = true;
+				q->ack_list.push_back(p);
 			q->crack_level = m_client->getCrackLevel();
 			q->crack_pos = m_client->getCrackPos();
 			q->urgent |= urgent;
-			for (std::size_t i = 1; i < q->map_blocks.size(); i++) {
+			for (std::size_t i = 0; i < q->map_blocks.size(); i++) {
 				if (!q->map_blocks[i]) {
-					MapBlock *block = map->getBlockNoCreateNoEx(q->p + g_26dirs[i - 1]);
+					MapBlock *block = map->getBlockNoCreateNoEx(q->p + g_64dirs[i]);
 					if (block) {
 						block->refGrab();
 						q->map_blocks[i] = block;
@@ -99,16 +113,13 @@ bool MeshUpdateQueue::addBlock(Map *map, v3s16 p, bool ack_block_to_server, bool
 	}
 
 	/*
-		Cache the block data (force-update the center block, don't update the
+		Make a list of blocks necessary for mesh generation and lock the blocks in memory.
-		neighbors but get them if they aren't already cached)
 	*/
-	std::vector<MapBlock *> cached_blocks;
+	std::vector<MapBlock *> map_blocks;
-	cached_blocks.reserve(3*3*3);
+	map_blocks.reserve(4*4*4);
-	cached_blocks.push_back(main_block);
+	for (v3s16 dp : g_64dirs) {
-	main_block->refGrab();
+		MapBlock *block = map->getBlockNoCreateNoEx(mesh_position + dp);
-	for (v3s16 dp : g_26dirs) {
+		map_blocks.push_back(block);
-		MapBlock *block = map->getBlockNoCreateNoEx(p + dp);
-		cached_blocks.push_back(block);
 		if (block)
 			block->refGrab();
 	}
@@ -117,12 +128,13 @@ bool MeshUpdateQueue::addBlock(Map *map, v3s16 p, bool ack_block_to_server, bool
 		Add the block
 	*/
 	QueuedMeshUpdate *q = new QueuedMeshUpdate;
-	q->p = p;
+	q->p = mesh_position;
-	q->ack_block_to_server = ack_block_to_server;
+	if(ack_block_to_server)
+		q->ack_list.push_back(p);
 	q->crack_level = m_client->getCrackLevel();
 	q->crack_pos = m_client->getCrackPos();
 	q->urgent = urgent;
-	q->map_blocks = std::move(cached_blocks);
+	q->map_blocks = std::move(map_blocks);
 	m_queue.push_back(q);
 
 	return true;
@@ -170,12 +182,14 @@ void MeshUpdateQueue::fillDataFromMapBlocks(QueuedMeshUpdate *q)
 {
 	MeshMakeData *data = new MeshMakeData(m_client, m_cache_enable_shaders);
 	q->data = data;
+	data->side_length = 2 * MAP_BLOCKSIZE;
 
 	data->fillBlockDataBegin(q->p);
 
-	for (MapBlock *block : q->map_blocks)
+	for (std::size_t i = 0; i < 64; i++) {
-		if (block)
+		MapBlock *block = q->map_blocks[i];
-			data->fillBlockData(block->getPos() - q->p, block->getData());
+		data->fillBlockData(g_64dirs[i], block ? block->getData() : block_placeholder.data);
+	}
 
 	data->setCrack(q->crack_level, q->crack_pos);
 	data->setSmoothLighting(m_cache_smooth_lighting);
@@ -208,7 +222,7 @@ void MeshUpdateWorkerThread::doUpdate()
 		r.p = q->p;
 		r.mesh = mesh_new;
 		r.solid_sides = get_solid_sides(q->data);
-		r.ack_block_to_server = q->ack_block_to_server;
+		r.ack_list = std::move(q->ack_list);
 		r.urgent = q->urgent;
 		r.map_blocks = q->map_blocks;
 

src/client/mesh_generator_thread.h

@@ -28,11 +28,12 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "util/thread.h"
 #include <vector>
 #include <memory>
+#include <unordered_map>
 
 struct QueuedMeshUpdate
 {
 	v3s16 p = v3s16(-1337, -1337, -1337);
-	bool ack_block_to_server = false;
+	std::vector<v3s16> ack_list;
 	int crack_level = -1;
 	v3s16 crack_pos;
 	MeshMakeData *data = nullptr; // This is generated in MeshUpdateQueue::pop()
@@ -96,8 +97,8 @@ struct MeshUpdateResult
 {
 	v3s16 p = v3s16(-1338, -1338, -1338);
 	MapBlockMesh *mesh = nullptr;
-	u8 solid_sides = 0;
+	std::unordered_map<v3s16, u8> solid_sides;
-	bool ack_block_to_server = false;
+	std::vector<v3s16> ack_list;
 	bool urgent = false;
 	std::vector<MapBlock *> map_blocks;
 

src/client/meshgen/collector.cpp

@@ -46,7 +46,7 @@ void MeshCollector::append(const TileLayer &layer, const video::S3DVertex *verti
 
 	u32 vertex_count = p.vertices.size();
 	for (u32 i = 0; i < numVertices; i++) {
-		p.vertices.emplace_back(vertices[i].Pos, vertices[i].Normal,
+		p.vertices.emplace_back(vertices[i].Pos + offset, vertices[i].Normal,
 				vertices[i].Color, scale * vertices[i].TCoords);
 		m_bounding_radius_sq = std::max(m_bounding_radius_sq,
 				(vertices[i].Pos - m_center_pos).getLengthSQ());
@@ -84,7 +84,7 @@ void MeshCollector::append(const TileLayer &layer, const video::S3DVertex *verti
 		video::SColor color = c;
 		if (!light_source)
 			applyFacesShading(color, vertices[i].Normal);
-		auto vpos = vertices[i].Pos + pos;
+		auto vpos = vertices[i].Pos + pos + offset;
 		p.vertices.emplace_back(vpos, vertices[i].Normal, color,
 				scale * vertices[i].TCoords);
 		m_bounding_radius_sq = std::max(m_bounding_radius_sq,

src/client/meshgen/collector.h

@@ -21,6 +21,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include <array>
 #include <vector>
 #include "irrlichttypes.h"
+#include "irr_v3d.h"
 #include <S3DVertex.h>
 #include "client/tile.h"
 
@@ -40,9 +41,11 @@ struct MeshCollector
 	// bounding sphere radius and center
 	f32 m_bounding_radius_sq = 0.0f;
 	v3f m_center_pos;
+	v3f offset;
 
 	// center_pos: pos to use for bounding-sphere, in BS-space
-	MeshCollector(const v3f center_pos) : m_center_pos(center_pos) {}
+	// offset: offset added to vertices
+	MeshCollector(const v3f center_pos, v3f offset = v3f()) : m_center_pos(center_pos), offset(offset) {}
 
 	// clang-format off
 	void append(const TileSpec &material,

src/client/wieldmesh.cpp

@@ -318,7 +318,7 @@ static scene::SMesh *createSpecialNodeMesh(Client *client, MapNode n,
 	std::vector<ItemPartColor> *colors, const ContentFeatures &f)
 {
 	MeshMakeData mesh_make_data(client, false);
-	MeshCollector collector(v3f(0.0f * BS));
+	MeshCollector collector(v3f(0.0f * BS), v3f());
 	mesh_make_data.setSmoothLighting(false);
 	MapblockMeshGenerator gen(&mesh_make_data, &collector,
 		client->getSceneManager()->getMeshManipulator());

src/map.cpp

@@ -325,6 +325,7 @@ void Map::timerUpdate(float dtime, float unload_timeout, s32 max_loaded_blocks,
 	u32 deleted_blocks_count = 0;
 	u32 saved_blocks_count = 0;
 	u32 block_count_all = 0;
+	u32 locked_blocks = 0;
 
 	const auto start_time = porting::getTimeUs();
 	beginSave();
@@ -396,8 +397,10 @@ void Map::timerUpdate(float dtime, float unload_timeout, s32 max_loaded_blocks,
 
 			MapBlock *block = b.block;
 
-			if (block->refGet() != 0)
+			if (block->refGet() != 0) {
+				locked_blocks++;
 				continue;
+			}
 
 			v3s16 p = block->getPos();
 
@@ -442,7 +445,7 @@ void Map::timerUpdate(float dtime, float unload_timeout, s32 max_loaded_blocks,
 				<<" blocks from memory";
 		if(save_before_unloading)
 			infostream<<", of which "<<saved_blocks_count<<" were written";
-		infostream<<", "<<block_count_all<<" blocks in memory";
+		infostream<<", "<<block_count_all<<" blocks in memory, " << locked_blocks << " locked";
 		infostream<<"."<<std::endl;
 		if(saved_blocks_count != 0){
 			PrintInfo(infostream); // ServerMap/ClientMap:

src/util/directiontables.cpp

@@ -110,6 +110,78 @@ const v3s16 g_27dirs[27] =
 	v3s16(0,0,0),
 };
 
+const v3s16 g_64dirs[64] =
+{
+	// +right, +top, +back
+	v3s16( -1, -1, -1),
+	v3s16( -1,  0, -1),
+	v3s16( -1,  1, -1),
+	v3s16( -1,  2, -1),
+	v3s16( -1, -1,  0),
+	v3s16( -1,  0,  0),
+	v3s16( -1,  1,  0),
+	v3s16( -1,  2,  0),
+	v3s16( -1, -1,  1),
+	v3s16( -1,  0,  1),
+	v3s16( -1,  1,  1),
+	v3s16( -1,  2,  1),
+	v3s16( -1, -1,  2),
+	v3s16( -1,  0,  2),
+	v3s16( -1,  1,  2),
+	v3s16( -1,  2,  2),
+
+	v3s16(  0, -1, -1),
+	v3s16(  0,  0, -1),
+	v3s16(  0,  1, -1),
+	v3s16(  0,  2, -1),
+	v3s16(  0, -1,  0),
+	v3s16(  0,  0,  0),
+	v3s16(  0,  1,  0),
+	v3s16(  0,  2,  0),
+	v3s16(  0, -1,  1),
+	v3s16(  0,  0,  1),
+	v3s16(  0,  1,  1),
+	v3s16(  0,  2,  1),
+	v3s16(  0, -1,  2),
+	v3s16(  0,  0,  2),
+	v3s16(  0,  1,  2),
+	v3s16(  0,  2,  2),
+
+	v3s16(  1, -1, -1),
+	v3s16(  1,  0, -1),
+	v3s16(  1,  1, -1),
+	v3s16(  1,  2, -1),
+	v3s16(  1, -1,  0),
+	v3s16(  1,  0,  0),
+	v3s16(  1,  1,  0),
+	v3s16(  1,  2,  0),
+	v3s16(  1, -1,  1),
+	v3s16(  1,  0,  1),
+	v3s16(  1,  1,  1),
+	v3s16(  1,  2,  1),
+	v3s16(  1, -1,  2),
+	v3s16(  1,  0,  2),
+	v3s16(  1,  1,  2),
+	v3s16(  1,  2,  2),
+
+	v3s16(  2, -1, -1),
+	v3s16(  2,  0, -1),
+	v3s16(  2,  1, -1),
+	v3s16(  2,  2, -1),
+	v3s16(  2, -1,  0),
+	v3s16(  2,  0,  0),
+	v3s16(  2,  1,  0),
+	v3s16(  2,  2,  0),
+	v3s16(  2, -1,  1),
+	v3s16(  2,  0,  1),
+	v3s16(  2,  1,  1),
+	v3s16(  2,  2,  1),
+	v3s16(  2, -1,  2),
+	v3s16(  2,  0,  2),
+	v3s16(  2,  1,  2),
+	v3s16(  2,  2,  2),
+};
+
 const u8 wallmounted_to_facedir[6] = {
 	20,
 	0,

src/util/directiontables.h

@@ -31,6 +31,9 @@ extern const v3s16 g_26dirs[26];
 // 26th is (0,0,0)
 extern const v3s16 g_27dirs[27];
 
+// all positions around an octablock in sector-first order
+extern const v3s16 g_64dirs[64];
+
 extern const u8 wallmounted_to_facedir[6];
 
 extern const v3s16 wallmounted_dirs[8];