Allow server side occlusion culling.

7 files changed, 92 insertions, 66 deletions

diff --git a/builtin/settingtypes.txt b/builtin/settingtypes.txt
index 4e800e25b..ffd872c20 100644
--- a/builtin/settingtypes.txt
+++ b/builtin/settingtypes.txt
@@ -864,6 +864,12 @@ liquid_update (Liquid update tick) float 1.0
 #    Stated in mapblocks (16 nodes)
 block_send_optimize_distance (block send optimize distance) int 4 2
 
+#    If enabled the server will perform map block occlusion culling based on
+#    on the eye position of the player. This can reduce the number of blocks
+#    sent to the client 50-80%. The client will not longer receive most invisible
+#    so that the utility of noclip mode is reduced.
+server_side_occlusion_culling (Server side occlusion culling) bool false
+
 [*Mapgen]
 
 #    Name of map generator to be used when creating a new world.
diff --git a/minetest.conf.example b/minetest.conf.example
index d53a00fd9..08d00d62a 100644
--- a/minetest.conf.example
+++ b/minetest.conf.example
@@ -1056,6 +1056,12 @@
 #    type: int min: 2
 # block_send_optimize_distance = 4
 
+#    If enabled the server will perform map block occlusion culling based on
+#    on the eye position of the player. This can reduce the number of blocks
+#    sent to the client 50-80%. The client will not longer receive most invisible
+#    so that the utility of noclip mode is reduced.
+server_side_occlusion_culling = false
+
 ## Mapgen
 
 #    Name of map generator to be used when creating a new world.
diff --git a/src/clientiface.cpp b/src/clientiface.cpp
index 0eb68c9c1..76a34c392 100644
--- a/src/clientiface.cpp
+++ b/src/clientiface.cpp
@@ -197,6 +197,9 @@ void RemoteClient::GetNextBlocks (
 	s32 nearest_sent_d = -1;
 	//bool queue_is_full = false;
 
+	const v3s16 cam_pos_nodes = floatToInt(camera_pos, BS);
+	const bool occ_cull = g_settings->getBool("server_side_occlusion_culling");
+
 	s16 d;
 	for(d = d_start; d <= d_max; d++) {
 		/*
@@ -298,6 +301,11 @@ void RemoteClient::GetNextBlocks (
 					if(block->getDayNightDiff() == false)
 						continue;
 				}
+
+				if (occ_cull && !block_is_invalid &&
+						env->getMap().isBlockOccluded(block, cam_pos_nodes)) {
+					continue;
+				}
 			}
 
 			/*
diff --git a/src/clientmap.cpp b/src/clientmap.cpp
index fb70a97e9..4cae03bf2 100644
--- a/src/clientmap.cpp
+++ b/src/clientmap.cpp
@@ -109,35 +109,6 @@ void ClientMap::OnRegisterSceneNode()
 	ISceneNode::OnRegisterSceneNode();
 }
 
-static bool isOccluded(Map *map, v3s16 p0, v3s16 p1, float step, float stepfac,
-		float start_off, float end_off, u32 needed_count, INodeDefManager *nodemgr)
-{
-	float d0 = (float)BS * p0.getDistanceFrom(p1);
-	v3s16 u0 = p1 - p0;
-	v3f uf = v3f(u0.X, u0.Y, u0.Z) * BS;
-	uf.normalize();
-	v3f p0f = v3f(p0.X, p0.Y, p0.Z) * BS;
-	u32 count = 0;
-	for(float s=start_off; s<d0+end_off; s+=step){
-		v3f pf = p0f + uf * s;
-		v3s16 p = floatToInt(pf, BS);
-		MapNode n = map->getNodeNoEx(p);
-		bool is_transparent = false;
-		const ContentFeatures &f = nodemgr->get(n);
-		if(f.solidness == 0)
-			is_transparent = (f.visual_solidness != 2);
-		else
-			is_transparent = (f.solidness != 2);
-		if(!is_transparent){
-			count++;
-			if(count >= needed_count)
-				return true;
-		}
-		step *= stepfac;
-	}
-	return false;
-}
-
 void ClientMap::getBlocksInViewRange(v3s16 cam_pos_nodes,
 		v3s16 *p_blocks_min, v3s16 *p_blocks_max)
 {
@@ -273,43 +244,7 @@ void ClientMap::updateDrawList(video::IVideoDriver* driver)
 			/*
 				Occlusion culling
 			*/
-			v3s16 cpn = block->getPos() * MAP_BLOCKSIZE;
-			cpn += v3s16(MAP_BLOCKSIZE / 2, MAP_BLOCKSIZE / 2, MAP_BLOCKSIZE / 2);
-			float step = BS * 1;
-			float stepfac = 1.1;
-			float startoff = BS * 1;
-			// The occlusion search of 'isOccluded()' must stop short of the target
-			// point by distance 'endoff' (end offset) to not enter the target mapblock.
-			// For the 8 mapblock corners 'endoff' must therefore be the maximum diagonal
-			// of a mapblock, because we must consider all view angles.
-			// sqrt(1^2 + 1^2 + 1^2) = 1.732
-			float endoff = -BS * MAP_BLOCKSIZE * 1.732050807569;
-			v3s16 spn = cam_pos_nodes;
-			s16 bs2 = MAP_BLOCKSIZE / 2 + 1;
-			// to reduce the likelihood of falsely occluded blocks
-			// require at least two solid blocks
-			// this is a HACK, we should think of a more precise algorithm
-			u32 needed_count = 2;
-			if (occlusion_culling_enabled &&
-					// For the central point of the mapblock 'endoff' can be halved
-					isOccluded(this, spn, cpn,
-						step, stepfac, startoff, endoff / 2.0f, needed_count, m_nodedef) &&
-					isOccluded(this, spn, cpn + v3s16(bs2,bs2,bs2),
-						step, stepfac, startoff, endoff, needed_count, m_nodedef) &&
-					isOccluded(this, spn, cpn + v3s16(bs2,bs2,-bs2),
-						step, stepfac, startoff, endoff, needed_count, m_nodedef) &&
-					isOccluded(this, spn, cpn + v3s16(bs2,-bs2,bs2),
-						step, stepfac, startoff, endoff, needed_count, m_nodedef) &&
-					isOccluded(this, spn, cpn + v3s16(bs2,-bs2,-bs2),
-						step, stepfac, startoff, endoff, needed_count, m_nodedef) &&
-					isOccluded(this, spn, cpn + v3s16(-bs2,bs2,bs2),
-						step, stepfac, startoff, endoff, needed_count, m_nodedef) &&
-					isOccluded(this, spn, cpn + v3s16(-bs2,bs2,-bs2),
-						step, stepfac, startoff, endoff, needed_count, m_nodedef) &&
-					isOccluded(this, spn, cpn + v3s16(-bs2,-bs2,bs2),
-						step, stepfac, startoff, endoff, needed_count, m_nodedef) &&
-					isOccluded(this, spn, cpn + v3s16(-bs2,-bs2,-bs2),
-						step, stepfac, startoff, endoff, needed_count, m_nodedef)) {
+			if (occlusion_culling_enabled && isBlockOccluded(block, cam_pos_nodes)) {
 				blocks_occlusion_culled++;
 				continue;
 			}
diff --git a/src/defaultsettings.cpp b/src/defaultsettings.cpp
index e9ee1135f..483c9cff6 100644
--- a/src/defaultsettings.cpp
+++ b/src/defaultsettings.cpp
@@ -282,6 +282,7 @@ void set_default_settings(Settings *settings)
 	// This causes frametime jitter on client side, or does it?
 	settings->setDefault("max_block_send_distance", "9");
 	settings->setDefault("block_send_optimize_distance", "4");
+	settings->setDefault("server_side_occlusion_culling", "false");
 	settings->setDefault("max_clearobjects_extra_loaded_blocks", "4096");
 	settings->setDefault("time_speed", "72");
 	settings->setDefault("server_unload_unused_data_timeout", "29");
diff --git a/src/map.cpp b/src/map.cpp
index a1502befa..43a49dc2f 100644
--- a/src/map.cpp
+++ b/src/map.cpp
@@ -1157,6 +1157,72 @@ void Map::removeNodeTimer(v3s16 p)
 	block->m_node_timers.remove(p_rel);
 }
 
+bool Map::isOccluded(v3s16 p0, v3s16 p1, float step, float stepfac,
+		float start_off, float end_off, u32 needed_count)
+{
+	float d0 = (float)BS * p0.getDistanceFrom(p1);
+	v3s16 u0 = p1 - p0;
+	v3f uf = v3f(u0.X, u0.Y, u0.Z) * BS;
+	uf.normalize();
+	v3f p0f = v3f(p0.X, p0.Y, p0.Z) * BS;
+	u32 count = 0;
+	for(float s=start_off; s<d0+end_off; s+=step){
+		v3f pf = p0f + uf * s;
+		v3s16 p = floatToInt(pf, BS);
+		MapNode n = getNodeNoEx(p);
+		const ContentFeatures &f = m_nodedef->get(n);
+		if(f.drawtype == NDT_NORMAL){
+			// not transparent, see ContentFeature::updateTextures
+			count++;
+			if(count >= needed_count)
+				return true;
+		}
+		step *= stepfac;
+	}
+	return false;
+}
+
+bool Map::isBlockOccluded(MapBlock *block, v3s16 cam_pos_nodes) {
+	v3s16 cpn = block->getPos() * MAP_BLOCKSIZE;
+	cpn += v3s16(MAP_BLOCKSIZE / 2, MAP_BLOCKSIZE / 2, MAP_BLOCKSIZE / 2);
+	float step = BS * 1;
+	float stepfac = 1.1;
+	float startoff = BS * 1;
+	// The occlusion search of 'isOccluded()' must stop short of the target
+	// point by distance 'endoff' (end offset) to not enter the target mapblock.
+	// For the 8 mapblock corners 'endoff' must therefore be the maximum diagonal
+	// of a mapblock, because we must consider all view angles.
+	// sqrt(1^2 + 1^2 + 1^2) = 1.732
+	float endoff = -BS * MAP_BLOCKSIZE * 1.732050807569;
+	v3s16 spn = cam_pos_nodes;
+	s16 bs2 = MAP_BLOCKSIZE / 2 + 1;
+	// to reduce the likelihood of falsely occluded blocks
+	// require at least two solid blocks
+	// this is a HACK, we should think of a more precise algorithm
+	u32 needed_count = 2;
+
+	return (
+		// For the central point of the mapblock 'endoff' can be halved
+		isOccluded(spn, cpn,
+			step, stepfac, startoff, endoff / 2.0f, needed_count) &&
+		isOccluded(spn, cpn + v3s16(bs2,bs2,bs2),
+			step, stepfac, startoff, endoff, needed_count) &&
+		isOccluded(spn, cpn + v3s16(bs2,bs2,-bs2),
+			step, stepfac, startoff, endoff, needed_count) &&
+		isOccluded(spn, cpn + v3s16(bs2,-bs2,bs2),
+			step, stepfac, startoff, endoff, needed_count) &&
+		isOccluded(spn, cpn + v3s16(bs2,-bs2,-bs2),
+			step, stepfac, startoff, endoff, needed_count) &&
+		isOccluded(spn, cpn + v3s16(-bs2,bs2,bs2),
+			step, stepfac, startoff, endoff, needed_count) &&
+		isOccluded(spn, cpn + v3s16(-bs2,bs2,-bs2),
+			step, stepfac, startoff, endoff, needed_count) &&
+		isOccluded(spn, cpn + v3s16(-bs2,-bs2,bs2),
+			step, stepfac, startoff, endoff, needed_count) &&
+		isOccluded(spn, cpn + v3s16(-bs2,-bs2,-bs2),
+			step, stepfac, startoff, endoff, needed_count));
+}
+
 /*
 	ServerMap
 */
diff --git a/src/map.h b/src/map.h
index c4181a49f..aeb05c704 100644
--- a/src/map.h
+++ b/src/map.h
@@ -314,6 +314,7 @@ public:
 	void transforming_liquid_add(v3s16 p);
 	s32 transforming_liquid_size();
 
+	bool isBlockOccluded(MapBlock *block, v3s16 cam_pos_nodes);
 protected:
 	friend class LuaVoxelManip;
 
@@ -335,6 +336,9 @@ protected:
 	// This stores the properties of the nodes on the map.
 	INodeDefManager *m_nodedef;
 
+	bool isOccluded(v3s16 p0, v3s16 p1, float step, float stepfac,
+			float start_off, float end_off, u32 needed_count);
+
 private:
 	f32 m_transforming_liquid_loop_count_multiplier;
 	u32 m_unprocessed_count;