Order drawlist by distance to the camera when rendering (#11651)

3 files changed, 104 insertions, 29 deletions

diff --git a/src/client/clientmap.cpp b/src/client/clientmap.cpp
index 77f3b9fe8..7cde085c8 100644
--- a/src/client/clientmap.cpp
+++ b/src/client/clientmap.cpp
@@ -73,7 +73,8 @@ ClientMap::ClientMap(
 		rendering_engine->get_scene_manager(), id),
 	m_client(client),
 	m_rendering_engine(rendering_engine),
-	m_control(control)
+	m_control(control),
+	m_drawlist(MapBlockComparer(v3s16(0,0,0)))
 {
 
 	/*
@@ -164,6 +165,8 @@ void ClientMap::updateDrawList()
 {
 	ScopeProfiler sp(g_profiler, "CM::updateDrawList()", SPT_AVG);
 
+	m_needs_update_drawlist = false;
+
 	for (auto &i : m_drawlist) {
 		MapBlock *block = i.second;
 		block->refDrop();
@@ -178,6 +181,7 @@ void ClientMap::updateDrawList()
 	const f32 camera_fov = m_camera_fov * 1.1f;
 
 	v3s16 cam_pos_nodes = floatToInt(camera_position, BS);
+
 	v3s16 p_blocks_min;
 	v3s16 p_blocks_max;
 	getBlocksInViewRange(cam_pos_nodes, &p_blocks_min, &p_blocks_max);
@@ -202,6 +206,8 @@ void ClientMap::updateDrawList()
 			occlusion_culling_enabled = false;
 	}
 
+	v3s16 camera_block = getContainerPos(cam_pos_nodes, MAP_BLOCKSIZE);
+	m_drawlist = std::map<v3s16, MapBlock*, MapBlockComparer>(MapBlockComparer(camera_block));
 
 	// Uncomment to debug occluded blocks in the wireframe mode
 	// TODO: Include this as a flag for an extended debugging setting
@@ -321,7 +327,20 @@ void ClientMap::renderMap(video::IVideoDriver* driver, s32 pass)
 		Draw the selected MapBlocks
 	*/
 
-	MeshBufListList drawbufs;
+	MeshBufListList grouped_buffers;
+
+	struct DrawDescriptor {
+		v3s16 m_pos;
+		scene::IMeshBuffer *m_buffer;
+		bool m_reuse_material;
+
+		DrawDescriptor(const v3s16 &pos, scene::IMeshBuffer *buffer, bool reuse_material) :
+			m_pos(pos), m_buffer(buffer), m_reuse_material(reuse_material)
+		{}
+	};
+
+	std::vector<DrawDescriptor> draw_order;
+	video::SMaterial previous_material;
 
 	for (auto &i : m_drawlist) {
 		v3s16 block_pos = i.first;
@@ -386,53 +405,76 @@ void ClientMap::renderMap(video::IVideoDriver* driver, s32 pass)
 						material.setFlag(video::EMF_WIREFRAME,
 							m_control.show_wireframe);
 
-						drawbufs.add(buf, block_pos, layer);
+						if (is_transparent_pass) {
+							// Same comparison as in MeshBufListList
+							bool new_material = material.getTexture(0) != previous_material.getTexture(0) ||
+									material != previous_material;
+
+							draw_order.emplace_back(block_pos, buf, !new_material);
+
+							if (new_material)
+								previous_material = material;
+						}
+						else {
+							grouped_buffers.add(buf, block_pos, layer);
+						}
 					}
 				}
 			}
 		}
 	}
 
+	// Capture draw order for all solid meshes
+	for (auto &lists : grouped_buffers.lists) {
+		for (MeshBufList &list : lists) {
+			// iterate in reverse to draw closest blocks first
+			for (auto it = list.bufs.rbegin(); it != list.bufs.rend(); ++it) {
+				draw_order.emplace_back(it->first, it->second, it != list.bufs.rbegin());
+			}
+		}
+	}
+
 	TimeTaker draw("Drawing mesh buffers");
 
 	core::matrix4 m; // Model matrix
 	v3f offset = intToFloat(m_camera_offset, BS);
+	u32 material_swaps = 0;
 
-	// Render all layers in order
-	for (auto &lists : drawbufs.lists) {
-		for (MeshBufList &list : lists) {
-			// Check and abort if the machine is swapping a lot
-			if (draw.getTimerTime() > 2000) {
-				infostream << "ClientMap::renderMap(): Rendering took >2s, " <<
-						"returning." << std::endl;
-				return;
-			}
+	// Render all mesh buffers in order
+	drawcall_count += draw_order.size();
+	for (auto &descriptor : draw_order) {
+		scene::IMeshBuffer *buf = descriptor.m_buffer;
 
+		// Check and abort if the machine is swapping a lot
+		if (draw.getTimerTime() > 2000) {
+			infostream << "ClientMap::renderMap(): Rendering took >2s, " <<
+					"returning." << std::endl;
+			return;
+		}
+
+		if (!descriptor.m_reuse_material) {
+			auto &material = buf->getMaterial();
 			// pass the shadow map texture to the buffer texture
 			ShadowRenderer *shadow = m_rendering_engine->get_shadow_renderer();
 			if (shadow && shadow->is_active()) {
-				auto &layer = list.m.TextureLayer[3];
+				auto &layer = material.TextureLayer[3];
 				layer.Texture = shadow->get_texture();
 				layer.TextureWrapU = video::E_TEXTURE_CLAMP::ETC_CLAMP_TO_EDGE;
 				layer.TextureWrapV = video::E_TEXTURE_CLAMP::ETC_CLAMP_TO_EDGE;
 				layer.TrilinearFilter = true;
 			}
+			driver->setMaterial(material);
+			++material_swaps;
+		}
 
-			driver->setMaterial(list.m);
-
-			drawcall_count += list.bufs.size();
-			for (auto &pair : list.bufs) {
-				scene::IMeshBuffer *buf = pair.second;
+		v3f block_wpos = intToFloat(descriptor.m_pos * MAP_BLOCKSIZE, BS);
+		m.setTranslation(block_wpos - offset);
 
-				v3f block_wpos = intToFloat(pair.first * MAP_BLOCKSIZE, BS);
-				m.setTranslation(block_wpos - offset);
-
-				driver->setTransform(video::ETS_WORLD, m);
-				driver->drawMeshBuffer(buf);
-				vertex_count += buf->getVertexCount();
-			}
-		}
+		driver->setTransform(video::ETS_WORLD, m);
+		driver->drawMeshBuffer(buf);
+		vertex_count += buf->getVertexCount();
 	}
+
 	g_profiler->avg(prefix + "draw meshes [ms]", draw.stop(true));
 
 	// Log only on solid pass because values are the same
@@ -440,8 +482,13 @@ void ClientMap::renderMap(video::IVideoDriver* driver, s32 pass)
 		g_profiler->avg("renderMap(): animated meshes [#]", mesh_animate_count);
 	}
 
+	if (pass == scene::ESNRP_TRANSPARENT) {
+		g_profiler->avg("renderMap(): transparent buffers [#]", draw_order.size());
+	}
+
 	g_profiler->avg(prefix + "vertices drawn [#]", vertex_count);
 	g_profiler->avg(prefix + "drawcalls [#]", drawcall_count);
+	g_profiler->avg(prefix + "material swaps [#]", material_swaps);
 }
 
 static bool getVisibleBrightness(Map *map, const v3f &p0, v3f dir, float step,
diff --git a/src/client/clientmap.h b/src/client/clientmap.h
index 97ce8d355..b4dc42395 100644
--- a/src/client/clientmap.h
+++ b/src/client/clientmap.h
@@ -87,10 +87,18 @@ public:
 
 	void updateCamera(const v3f &pos, const v3f &dir, f32 fov, const v3s16 &offset)
 	{
+		v3s16 previous_block = getContainerPos(floatToInt(m_camera_position, BS) + m_camera_offset, MAP_BLOCKSIZE);
+
 		m_camera_position = pos;
 		m_camera_direction = dir;
 		m_camera_fov = fov;
 		m_camera_offset = offset;
+
+		v3s16 current_block = getContainerPos(floatToInt(m_camera_position, BS) + m_camera_offset, MAP_BLOCKSIZE);
+
+		// reorder the blocks when camera crosses block boundary
+		if (previous_block != current_block)
+			m_needs_update_drawlist = true;
 	}
 
 	/*
@@ -122,6 +130,8 @@ public:
 		v3s16 *p_blocks_min, v3s16 *p_blocks_max, float range=-1.0f);
 	void updateDrawList();
 	void updateDrawListShadow(const v3f &shadow_light_pos, const v3f &shadow_light_dir, float shadow_range);
+	// Returns true if draw list needs updating before drawing the next frame.
+	bool needsUpdateDrawList() { return m_needs_update_drawlist; }
 	void renderMap(video::IVideoDriver* driver, s32 pass);
 
 	void renderMapShadows(video::IVideoDriver *driver,
@@ -140,6 +150,23 @@ public:
 	f32 getCameraFov() const { return m_camera_fov; }
 
 private:
+	// Orders blocks by distance to the camera
+	class MapBlockComparer
+	{
+	public:
+		MapBlockComparer(const v3s16 &camera_block) : m_camera_block(camera_block) {}
+
+		bool operator() (const v3s16 &left, const v3s16 &right) const
+		{
+			auto distance_left = left.getDistanceFromSQ(m_camera_block);
+			auto distance_right = right.getDistanceFromSQ(m_camera_block);
+			return distance_left > distance_right || (distance_left == distance_right && left > right);
+		}
+
+	private:
+		v3s16 m_camera_block;
+	};
+
 	Client *m_client;
 	RenderingEngine *m_rendering_engine;
 
@@ -153,8 +180,9 @@ private:
 	f32 m_camera_fov = M_PI;
 	v3s16 m_camera_offset;
 
-	std::map<v3s16, MapBlock*> m_drawlist;
+	std::map<v3s16, MapBlock*, MapBlockComparer> m_drawlist;
 	std::map<v3s16, MapBlock*> m_drawlist_shadow;
+	bool m_needs_update_drawlist;
 
 	std::set<v2s16> m_last_drawn_sectors;
 
diff --git a/src/client/game.cpp b/src/client/game.cpp
index f7fd7abf9..a6448f40d 100644
--- a/src/client/game.cpp
+++ b/src/client/game.cpp
@@ -3897,8 +3897,8 @@ void Game::updateFrame(ProfilerGraph *graph, RunStats *stats, f32 dtime,
 	v3f camera_direction = camera->getDirection();
 	if (runData.update_draw_list_timer >= update_draw_list_delta
 			|| runData.update_draw_list_last_cam_dir.getDistanceFrom(camera_direction) > 0.2
-			|| m_camera_offset_changed) {
-
+			|| m_camera_offset_changed
+			|| client->getEnv().getClientMap().needsUpdateDrawList()) {
 		runData.update_draw_list_timer = 0;
 		client->getEnv().getClientMap().updateDrawList();
 		runData.update_draw_list_last_cam_dir = camera_direction;