Generalize mesh chunking, and make it configurable. (#13179)

* Generalize mesh chunking. Set 3x3x3 chunks.

* Make mesh chunk size configurable... Default to 1 (off).

* Extract all mesh grid maths into a dedicated class

---------

Co-authored-by: x2048 <codeforsmile@gmail.com>

builtin/settingtypes.txt

@@ -1713,6 +1713,13 @@ world_aligned_mode (World-aligned textures mode) enum enable disable,enable,forc
 #    Warning: This option is EXPERIMENTAL!
 autoscale_mode (Autoscaling mode) enum disable disable,enable,force
 
+#    Side length of a cube of map blocks that the client will consider together
+#    when generating meshes.
+#    Larger values increase the utilization of the GPU by reducing the number of
+#    draw calls, benefiting especially high-end GPUs.
+#    Systems with a low-end GPU (or no GPU) would benefit from smaller values.
+client_mesh_chunk (Client Mesh Chunksize) int 1 1 16
+
 [**Font]
 
 font_bold (Font bold by default) bool false

src/client/client.cpp

@@ -143,6 +143,7 @@ Client::Client(
 	}
 
 	m_cache_save_interval = g_settings->getU16("server_map_save_interval");
+	m_mesh_grid = { g_settings->getU16("client_mesh_chunk") };
 }
 
 void Client::migrateModStorage()
@@ -564,7 +565,7 @@ void Client::step(float dtime)
 			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.
+			// create a blank block just to hold the chunk's mesh.
 			// If the block becomes visible later it will replace the blank block.
 			if (!block && r.mesh)
 				block = sector->createBlankBlock(r.p.Y);
@@ -607,10 +608,10 @@ void Client::step(float dtime)
 				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;
+				for (ofs.Z = 0; ofs.Z < m_mesh_grid.cell_size; ofs.Z++)
+				for (ofs.Y = 0; ofs.Y < m_mesh_grid.cell_size; ofs.Y++)
+				for (ofs.X = 0; ofs.X < m_mesh_grid.cell_size; ofs.X++) {
+					size_t i = m_mesh_grid.getOffsetIndex(ofs);
 					if (i < minimap_mapblocks.size() && minimap_mapblocks[i])
 						m_minimap->addBlock(r.p + ofs, minimap_mapblocks[i]);
 				}

src/client/client.h

@@ -39,6 +39,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "network/peerhandler.h"
 #include "gameparams.h"
 #include <fstream>
+#include "util/numeric.h"
 
 #define CLIENT_CHAT_MESSAGE_LIMIT_PER_10S 10.0f
 
@@ -437,6 +438,11 @@ public:
 	{
 		return m_env.getLocalPlayer()->formspec_prepend;
 	}
+	inline MeshGrid getMeshGrid()
+	{
+		return m_mesh_grid;
+	}
+
 private:
 	void loadMods();
 
@@ -602,4 +608,7 @@ private:
 	u32 m_csm_restriction_noderange = 8;
 
 	std::unique_ptr<ModChannelMgr> m_modchannel_mgr;
+
+	// The number of blocks the client will combine for mesh generation.
+	MeshGrid m_mesh_grid;
 };

src/client/clientmap.cpp

@@ -304,6 +304,7 @@ void ClientMap::updateDrawList()
 	blocks_seen.getChunk(camera_block).getBits(camera_block) = 0x07; // mark all sides as visible
 
 	std::set<v3s16> shortlist;
+	MeshGrid mesh_grid = m_client->getMeshGrid();
 
 	// Recursively walk the space and pick mapblocks for drawing
 	while (blocks_to_consider.size() > 0) {
@@ -330,7 +331,6 @@ void ClientMap::updateDrawList()
 
 		MapBlockMesh *mesh = block ? block->mesh : nullptr;
 
-
 		// Calculate the coordinates for range and frutum culling
 		v3f mesh_sphere_center;
 		f32 mesh_sphere_radius;
@@ -376,13 +376,21 @@ void ClientMap::updateDrawList()
 			continue;
 		}
 
-		// Block meshes are stored in blocks where all coordinates are even (lowest bit set to 0)
-		// Add them to the de-dup 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 keeplist right away.
-		if (block) {
-			m_keeplist.push_back(block);
+		if (mesh_grid.cell_size > 1) {
+			// Block meshes are stored in the corner block of a chunk
+			// (where all coordinate are divisible by the chunk size)
+			// Add them to the de-dup set.
+			shortlist.emplace(mesh_grid.getMeshPos(block_coord.X), mesh_grid.getMeshPos(block_coord.Y), mesh_grid.getMeshPos(block_coord.Z));
+			// All other blocks we can grab and add to the keeplist right away.
+			if (block) {
+				m_keeplist.push_back(block);
+				block->refGrab();
+			}
+		}
+		else if (mesh) {
+			// without mesh chunking we can add the block to the drawlist
 			block->refGrab();
+			m_drawlist.emplace(block_coord, block);
 		}
 
 		// Decide which sides to traverse next or to block away
@@ -485,7 +493,7 @@ void ClientMap::updateDrawList()
 
 	g_profiler->avg("MapBlocks shortlist [#]", shortlist.size());
 
-	assert(m_drawlist.empty());
+	assert(m_drawlist.empty() || shortlist.empty());
 	for (auto pos : shortlist) {
 		MapBlock * block = getBlockNoCreateNoEx(pos);
 		if (block) {
@@ -612,6 +620,7 @@ void ClientMap::renderMap(video::IVideoDriver* driver, s32 pass)
 
 	auto is_frustum_culled = m_client->getCamera()->getFrustumCuller();
 
+	const MeshGrid mesh_grid = m_client->getMeshGrid();
 	for (auto &i : m_drawlist) {
 		v3s16 block_pos = i.first;
 		MapBlock *block = i.second;
@@ -740,7 +749,7 @@ void ClientMap::renderMap(video::IVideoDriver* driver, s32 pass)
 			material.TextureLayer[ShadowRenderer::TEXTURE_LAYER_SHADOW].Texture = nullptr;
 		}
 
-		v3f block_wpos = intToFloat(descriptor.m_pos / 8 * 8 * MAP_BLOCKSIZE, BS);
+		v3f block_wpos = intToFloat(mesh_grid.getMeshPos(descriptor.m_pos) * MAP_BLOCKSIZE, BS);
 		m.setTranslation(block_wpos - offset);
 
 		driver->setTransform(video::ETS_WORLD, m);
@@ -978,6 +987,7 @@ void ClientMap::renderMapShadows(video::IVideoDriver *driver,
 		return;
 	}
 
+	const MeshGrid mesh_grid = m_client->getMeshGrid();
 	for (const auto &i : m_drawlist_shadow) {
 		// only process specific part of the list & break early
 		++count;
@@ -1066,7 +1076,7 @@ void ClientMap::renderMapShadows(video::IVideoDriver *driver,
 			++material_swaps;
 		}
 
-		v3f block_wpos = intToFloat(descriptor.m_pos / 8 * 8 * MAP_BLOCKSIZE, BS);
+		v3f block_wpos = intToFloat(mesh_grid.getMeshPos(descriptor.m_pos) * MAP_BLOCKSIZE, BS);
 		m.setTranslation(block_wpos - offset);
 
 		driver->setTransform(video::ETS_WORLD, m);

src/client/mapblock_mesh.cpp

@@ -38,7 +38,9 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 
 MeshMakeData::MeshMakeData(Client *client, bool use_shaders):
 	m_client(client),
-	m_use_shaders(use_shaders)
+	m_use_shaders(use_shaders),
+	m_mesh_grid(client->getMeshGrid()),
+	side_length(MAP_BLOCKSIZE * m_mesh_grid.cell_size)
 {}
 
 void MeshMakeData::fillBlockDataBegin(const v3s16 &blockpos)
@@ -53,12 +55,11 @@ void MeshMakeData::fillBlockDataBegin(const v3s16 &blockpos)
 	m_vmanip.addArea(voxel_area);
 }
 
-void MeshMakeData::fillBlockData(const v3s16 &block_offset, MapNode *data)
+void MeshMakeData::fillBlockData(const v3s16 &bp, MapNode *data)
 {
 	v3s16 data_size(MAP_BLOCKSIZE, MAP_BLOCKSIZE, MAP_BLOCKSIZE);
 	VoxelArea data_area(v3s16(0,0,0), data_size - v3s16(1,1,1));
 
-	v3s16 bp = m_blockpos + block_offset;
 	v3s16 blockpos_nodes = bp * MAP_BLOCKSIZE;
 	m_vmanip.copyFrom(data, data_area, v3s16(0,0,0), blockpos_nodes, data_size);
 }
@@ -1179,18 +1180,18 @@ MapBlockMesh::MapBlockMesh(MeshMakeData *data, v3s16 camera_offset):
 
 	v3s16 bp = data->m_blockpos;
 	// Only generate minimap mapblocks at even coordinates.
-	if (((bp.X | bp.Y | bp.Z) & 1) == 0 && data->m_client->getMinimap()) {
-		m_minimap_mapblocks.resize(8, nullptr);
+	if (data->m_mesh_grid.isMeshPos(bp) && data->m_client->getMinimap()) {
+		m_minimap_mapblocks.resize(data->m_mesh_grid.getCellVolume(), 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++) {
+		for (ofs.Z = 0; ofs.Z < data->m_mesh_grid.cell_size; ofs.Z++)
+		for (ofs.Y = 0; ofs.Y < data->m_mesh_grid.cell_size; ofs.Y++)
+		for (ofs.X = 0; ofs.X < data->m_mesh_grid.cell_size; 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;
+				m_minimap_mapblocks[data->m_mesh_grid.getOffsetIndex(ofs)] = block;
 				block->getMinimapNodes(&data->m_vmanip, p);
 			}
 		}
@@ -1221,7 +1222,7 @@ MapBlockMesh::MapBlockMesh(MeshMakeData *data, v3s16 camera_offset):
 		Convert FastFaces to MeshCollector
 	*/
 
-	v3f offset = intToFloat((data->m_blockpos - data->m_blockpos / 8 * 8) * MAP_BLOCKSIZE, BS);
+	v3f offset = intToFloat((data->m_blockpos - data->m_mesh_grid.getMeshPos(data->m_blockpos)) * MAP_BLOCKSIZE, BS);
 	MeshCollector collector(m_bounding_sphere_center, offset);
 
 	{
@@ -1584,10 +1585,11 @@ std::unordered_map<v3s16, u8> get_solid_sides(MeshMakeData *data)
 {
 	std::unordered_map<v3s16, u8> results;
 	v3s16 ofs;
+	const u16 mesh_chunk = data->side_length / MAP_BLOCKSIZE;
 
-	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++) {
+	for (ofs.X = 0; ofs.X < mesh_chunk; ofs.X++)
+	for (ofs.Y = 0; ofs.Y < mesh_chunk; ofs.Y++)
+	for (ofs.Z = 0; ofs.Z < mesh_chunk; ofs.Z++) {
 		v3s16 blockpos = data->m_blockpos + ofs;
 		v3s16 blockpos_nodes = blockpos * MAP_BLOCKSIZE;
 		const NodeDefManager *ndef = data->m_client->ndef();

src/client/mapblock_mesh.h

@@ -43,6 +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;
+	MeshGrid m_mesh_grid;
 	u16 side_length = MAP_BLOCKSIZE;
 
 	Client *m_client;
@@ -54,7 +55,7 @@ struct MeshMakeData
 		Copy block data manually (to allow optimizations by the caller)
 	*/
 	void fillBlockDataBegin(const v3s16 &blockpos);
-	void fillBlockData(const v3s16 &block_offset, MapNode *data);
+	void fillBlockData(const v3s16 &bp, MapNode *data);
 
 	/*
 		Set the (node) position of a crack

src/client/mesh_generator_thread.cpp

@@ -77,9 +77,11 @@ 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);
+	MeshGrid mesh_grid = m_client->getMeshGrid();
+
+	// Mesh is placed at the corner block of a chunk
+	// (where all coordinate are divisible by the chunk size)
+	v3s16 mesh_position(mesh_grid.getMeshPos(p));
 	/*
 		Mark the block as urgent if requested
 	*/
@@ -99,14 +101,19 @@ bool MeshUpdateQueue::addBlock(Map *map, v3s16 p, bool ack_block_to_server, bool
 			q->crack_level = m_client->getCrackLevel();
 			q->crack_pos = m_client->getCrackPos();
 			q->urgent |= urgent;
-			for (std::size_t i = 0; i < q->map_blocks.size(); i++) {
+			v3s16 pos;
+			int i = 0;
+			for (pos.X = q->p.X - 1; pos.X <= q->p.X + mesh_grid.cell_size; pos.X++)
+			for (pos.Z = q->p.Z - 1; pos.Z <= q->p.Z + mesh_grid.cell_size; pos.Z++)
+			for (pos.Y = q->p.Y - 1; pos.Y <= q->p.Y + mesh_grid.cell_size; pos.Y++) {
 				if (!q->map_blocks[i]) {
-					MapBlock *block = map->getBlockNoCreateNoEx(q->p + g_64dirs[i]);
+					MapBlock *block = map->getBlockNoCreateNoEx(pos);
 					if (block) {
 						block->refGrab();
 						q->map_blocks[i] = block;
 					}
 				}
+				i++;
 			}
 			return true;
 		}
@@ -116,9 +123,12 @@ bool MeshUpdateQueue::addBlock(Map *map, v3s16 p, bool ack_block_to_server, bool
 		Make a list of blocks necessary for mesh generation and lock the blocks in memory.
 	*/
 	std::vector<MapBlock *> map_blocks;
-	map_blocks.reserve(4*4*4);
-	for (v3s16 dp : g_64dirs) {
-		MapBlock *block = map->getBlockNoCreateNoEx(mesh_position + dp);
+	map_blocks.reserve((mesh_grid.cell_size+2)*(mesh_grid.cell_size+2)*(mesh_grid.cell_size+2));
+	v3s16 pos;
+	for (pos.X = mesh_position.X - 1; pos.X <= mesh_position.X + mesh_grid.cell_size; pos.X++)
+	for (pos.Z = mesh_position.Z - 1; pos.Z <= mesh_position.Z + mesh_grid.cell_size; pos.Z++)
+	for (pos.Y = mesh_position.Y - 1; pos.Y <= mesh_position.Y + mesh_grid.cell_size; pos.Y++) {
+		MapBlock *block = map->getBlockNoCreateNoEx(pos);
 		map_blocks.push_back(block);
 		if (block)
 			block->refGrab();
@@ -182,13 +192,16 @@ 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 (std::size_t i = 0; i < 64; i++) {
-		MapBlock *block = q->map_blocks[i];
-		data->fillBlockData(g_64dirs[i], block ? block->getData() : block_placeholder.data);
+	v3s16 pos;
+	int i = 0;
+	for (pos.X = q->p.X - 1; pos.X <= q->p.X + data->m_mesh_grid.cell_size; pos.X++)
+	for (pos.Z = q->p.Z - 1; pos.Z <= q->p.Z + data->m_mesh_grid.cell_size; pos.Z++)
+	for (pos.Y = q->p.Y - 1; pos.Y <= q->p.Y + data->m_mesh_grid.cell_size; pos.Y++) {
+		MapBlock *block = q->map_blocks[i++];
+		data->fillBlockData(pos, block ? block->getData() : block_placeholder.data);
 	}
 
 	data->setCrack(q->crack_level, q->crack_pos);

src/defaultsettings.cpp

@@ -185,6 +185,7 @@ void set_default_settings()
 	settings->setDefault("fps_max", "60");
 	settings->setDefault("fps_max_unfocused", "20");
 	settings->setDefault("viewing_range", "190");
+	settings->setDefault("client_mesh_chunk", "1");
 #if ENABLE_GLES
 	settings->setDefault("near_plane", "0.1");
 #endif

src/util/directiontables.cpp

@@ -110,78 +110,6 @@ 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

@@ -31,9 +31,6 @@ 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];

src/util/numeric.h

@@ -145,6 +145,37 @@ inline v3s16 componentwise_max(const v3s16 &a, const v3s16 &b)
 	return v3s16(MYMAX(a.X, b.X), MYMAX(a.Y, b.Y), MYMAX(a.Z, b.Z));
 }
 
+/// @brief Describes a grid with given step, oirginating at (0,0,0)
+struct MeshGrid {
+	u16 cell_size;
+
+	u32 getCellVolume() const { return cell_size * cell_size * cell_size; }
+
+	/// @brief returns closest step of the grid smaller than p
+	s16 getMeshPos(s16 p) const
+	{
+		return ((p - (p < 0) * (cell_size - 1)) / cell_size * cell_size);
+	}
+
+	/// @brief Returns coordinates of the origin of the grid cell containing p
+	v3s16 getMeshPos(v3s16 p) const
+	{
+		return v3s16(getMeshPos(p.X), getMeshPos(p.Y), getMeshPos(p.Z));
+	}
+	
+	/// @brief Returns true if p is an origin of a cell in the grid.
+	bool isMeshPos(v3s16 &p) const
+	{
+		return ((p.X + p.Y + p.Z) % cell_size) == 0;
+	}
+
+	/// @brief Returns index of the given offset in a grid cell
+	/// All offset coordinates must be smaller than the size of the cell
+	u16 getOffsetIndex(v3s16 offset) const
+	{
+		return (offset.Z * cell_size + offset.Y) * cell_size + offset.X;
+	}
+};
 
 /** Returns \p f wrapped to the range [-360, 360]
  *