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_mapblock = r.mesh->moveMinimapMapblock();
-					if (minimap_mapblock == NULL)
+					minimap_mapblocks = r.mesh->moveMinimapMapblocks();
+					if (minimap_mapblocks.empty())
 						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)
-				m_minimap->addBlock(r.p, minimap_mapblock);
+			for (auto p : r.solid_sides) {
+				auto block = m_env.getMap().getBlockNoCreateNoEx(p.first);
+				if (block)
+					block->solid_sides = p.second;
+			}
+
+			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]);
+				}
+			}
 
-			if (r.ack_block_to_server) {
+			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
-		if (mesh) {
-			// Add to set
+		// 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 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 @@ class ClientMap : public Map, public scene::ISceneNode
 
 	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.Y = 0; p.Y < MAP_BLOCKSIZE; p.Y++)
-	for (p.X = 0; p.X < MAP_BLOCKSIZE; p.X++) {
+	for (p.Z = 0; p.Z < data->side_length; p.Z++)
+	for (p.Y = 0; p.Y < data->side_length; p.Y++)
+	for (p.X = 0; p.X < data->side_length; p.X++) {
 		n = data->m_vmanip.getNodeNoEx(blockpos_nodes + p);
 		f = &nodedef->get(n);
 		drawNode();