Tracer replacement (#3704)

* Replaced cTracer usage with cLineBlockTracer.

* Exported new cLineBlockTracer utility functions to Lua API.

Server/Plugins/APIDump/Classes/Geometry.lua

@@ -977,52 +977,103 @@ return
 	{
 		Desc = [[
 This class provides an easy-to-use interface for tracing lines through individual
-blocks in the world. It will call the provided callbacks according to what events it encounters along the
+blocks in the world. It can either be used to call the provided callbacks according
-way.</p>
+to what events it encounters along the way, or there are shortcut functions used for
-<p>
+the most popular tracing reasons - line of sight and solid hits.
-For the Lua API, there's only one static function exported that takes all the parameters necessary to do
-the tracing. The Callbacks parameter is a table containing all the functions that will be called upon the
-various events. See below for further information.
 		]],
 		Functions =
 		{
+			FirstSolidHitTrace =
+			{
+				{
+					IsStatic = true,
+					Params =
+					{
+						{ Name = "World",  Type = "cWorld" },
+						{ Name = "StartX", Type = "number" },
+						{ Name = "StartY", Type = "number" },
+						{ Name = "StartZ", Type = "number" },
+						{ Name = "EndX",   Type = "number" },
+						{ Name = "EndY",   Type = "number" },
+						{ Name = "EndZ",   Type = "number" },
+					},
+					Returns =
+					{
+						{ Name = "HasHitSolid",    Type = "boolean" },
+						{ Name = "HitCoords",      Type = "Vector3d" },
+						{ Name = "HitBlockCoords", Type = "Vector3i" },
+						{ Name = "HitBlockFace",   Type = "eBlockFace" },
+					},
+					Notes = "If the specified line hits a solid block, return true and the coordinates / face of the first such solid block hit. Returns false if there's no solid block on that line.",
+				},
+				{
+					IsStatic = true,
+					Params =
+					{
+						{ Name = "World", Type = "cWorld" },
+						{ Name = "Start", Type = "Vector3d" },
+						{ Name = "End",   Type = "Vector3d" },
+					},
+					Returns =
+					{
+						{ Name = "HasHitSolid",    Type = "boolean" },
+						{ Name = "HitCoords",      Type = "Vector3d" },
+						{ Name = "HitBlockCoords", Type = "Vector3i" },
+						{ Name = "HitBlockFace",   Type = "eBlockFace" },
+					},
+					Notes = "If the specified line hits a solid block, return true and the coordinates / face of the first such solid block hit. Returns false if there's no solid block on that line.",
+				},
+			},  -- FirstSolidHitTrace
+			LineOfSightTrace =
+			{
+				{
+					IsStatic = true,
+					Params =
+					{
+						{ Name = "World",  Type = "cWorld" },
+						{ Name = "StartX", Type = "number" },
+						{ Name = "StartY", Type = "number" },
+						{ Name = "StartZ", Type = "number" },
+						{ Name = "EndX",   Type = "number" },
+						{ Name = "EndY",   Type = "number" },
+						{ Name = "EndZ",   Type = "number" },
+						{ Name = "Sight",  Type = "number" },
+					},
+					Returns =
+					{
+						{ Name = "CanSee", Type = "boolean" },
+					},
+					Notes = "Returns true if the two points specified are within line of sight of each other. The Sight parameter specifies which blocks are considered transparent for the trace, it is a combination of {{cLineBlockTracer#eLineOfSight|losXXX}} values added together."
+				},
+				{
+					IsStatic = true,
+					Params =
+					{
+						{ Name = "World", Type = "cWorld" },
+						{ Name = "Start", Type = "Vector3d" },
+						{ Name = "End",   Type = "Vector3d" },
+						{ Name = "Sight", Type = "number" },
+					},
+					Returns =
+					{
+						{ Name = "CanSee", Type = "boolean" },
+					},
+					Notes = "Returns true if the two points specified are within line of sight of each other. The Sight parameter specifies which blocks are considered transparent for the trace, it is a combination of {{cLineBlockTracer#eLineOfSight|losXXX}} values added together."
+				},
+			},  -- LineOfSightTrace
 			Trace =
 			{
 				IsStatic = true,
 				Params =
 				{
-					{
+					{ Name = "World",     Type = "cWorld" },
-						Name = "World",
+					{ Name = "Callbacks", Type = "table" },
-						Type = "cWorld",
+					{ Name = "StartX",    Type = "number" },
-					},
+					{ Name = "StartY",    Type = "number" },
-					{
+					{ Name = "StartZ",    Type = "number" },
-						Name = "Callbacks",
+					{ Name = "EndX",      Type = "number" },
-						Type = "table",
+					{ Name = "EndY",      Type = "number" },
-					},
+					{ Name = "EndZ",      Type = "number" },
-					{
-						Name = "StartX",
-						Type = "number",
-					},
-					{
-						Name = "StartY",
-						Type = "number",
-					},
-					{
-						Name = "StartZ",
-						Type = "number",
-					},
-					{
-						Name = "EndX",
-						Type = "number",
-					},
-					{
-						Name = "EndY",
-						Type = "number",
-					},
-					{
-						Name = "EndZ",
-						Type = "number",
-					},
 				},
 				Returns =
 				{
@@ -1033,6 +1084,29 @@ various events. See below for further information.
 				Notes = "Performs the trace on the specified line. Returns true if the entire trace was processed (no callback returned true)",
 			},
 		},
+		Constants =
+		{
+			losAir =
+			{
+				Notes = "LineOfSight tracing can 'see' through air blocks.",
+			},
+			losWater =
+			{
+				Notes = "LineOfSight tracing can 'see' through water blocks.",
+			},
+			losLava =
+			{
+				Notes = "LineOfSight tracing can 'see' through lava blocks.",
+			},
+		},
+		ConstantGroups =
+		{
+			eLineOfSight =
+			{
+				Include = "los.*",
+				TextBefore = "The following constants are used to speficy which blocks are see-through when tracing a LineOfSight trace. Add them together to make up the Sight parameter.",
+			},
+		},
 		AdditionalInfo =
 		{
 			{
@@ -1109,16 +1183,15 @@ end
 	cTracer =
 	{
 		Desc = [[
-			A cTracer object is used to trace lines in the world. One thing you can use the cTracer for, is
+			This class is <b>OBSOLETE</b>, do not use it.
-			tracing what block a player is looking at, but you can do more with it if you want.</p>
+			See the {{cLineBlockTracer}} class for the replacement.
-			<p>
-			The cTracer is still a work in progress and is not documented at all.</p>
-			<p>
-			See also the {{cLineBlockTracer}} class for an alternative approach using callbacks.
 		]],
 		Functions =
 		{
-
+			Trace =
+			{
+				Notes = "<b>OBSOLETE</b>, use the {{cLineBlockTracer}} class instead.",
+			},
 		},
 	},
 	Vector3d =

Server/Plugins/Debuggers/Debuggers.lua

@@ -1838,6 +1838,44 @@ end
 
 
 
+function HandleConsoleHitTrace(a_Split)
+	local world = cRoot:Get():GetDefaultWorld()
+	local s = Vector3d(0, 70, 0)
+	local e = Vector3d(100, 75, 100)
+	if (tonumber(a_Split[2])) then
+		s.x = tonumber(a_Split[2])
+	end
+	if (tonumber(a_Split[3])) then
+		s.y = tonumber(a_Split[3])
+	end
+	if (tonumber(a_Split[4])) then
+		s.z = tonumber(a_Split[4])
+	end
+	if (tonumber(a_Split[5])) then
+		e.x = tonumber(a_Split[5])
+	end
+	if (tonumber(a_Split[6])) then
+		e.y = tonumber(a_Split[6])
+	end
+	if (tonumber(a_Split[7])) then
+		e.z = tonumber(a_Split[7])
+	end
+	local res, hitCoords, hitBlockCoords, hitBlockFace = cLineBlockTracer:FirstSolidHitTrace(world, s, e)
+	if (res) then
+		return true, string.format("The line hits block {%d, %d, %d} at point {%f, %f, %f}, face %s",
+			hitBlockCoords.x, hitBlockCoords.y, hitBlockCoords.z,
+			hitCoords.x, hitCoords.y, hitCoords.z,
+			BlockFaceToString(hitBlockFace)
+		)
+	else
+		return true, "The two points specified don't have a solid block between them."
+	end
+end
+
+
+
+
+
 --- Monitors the state of the "inh" entity-spawning hook
 -- if false, the hook is installed before the "inh" command processing
 local isInhHookInstalled = false
@@ -1954,6 +1992,40 @@ end
 
 
 
+function HandleConsoleLosTrace(a_Split)
+	local world = cRoot:Get():GetDefaultWorld()
+	local s = Vector3d(0, 70, 0)
+	local e = Vector3d(100, 75, 100)
+	if (tonumber(a_Split[2])) then
+		s.x = tonumber(a_Split[2])
+	end
+	if (tonumber(a_Split[3])) then
+		s.y = tonumber(a_Split[3])
+	end
+	if (tonumber(a_Split[4])) then
+		s.z = tonumber(a_Split[4])
+	end
+	if (tonumber(a_Split[5])) then
+		e.x = tonumber(a_Split[5])
+	end
+	if (tonumber(a_Split[6])) then
+		e.y = tonumber(a_Split[6])
+	end
+	if (tonumber(a_Split[7])) then
+		e.z = tonumber(a_Split[7])
+	end
+	local res = cLineBlockTracer:LineOfSightTrace(world, s, e, cLineBlockTracer.losAir)
+	if (res) then
+		return true, "The two points can see each other."
+	else
+		return true, "The two points cannot see each other"
+	end
+end
+
+
+
+
+
 function HandleConsolePluginStats(a_Split)
 	cPluginManager:ForEachPlugin(
 		function (a_CBPlugin)

Server/Plugins/Debuggers/Info.lua

@@ -290,6 +290,12 @@ g_PluginInfo =
 			HelpString = "Tests the crypto hashing functions",
 		},
 
+		["hittrace"] =
+		{
+			Handler = HandleConsoleHitTrace,
+			HelpString = "Tests the FirstSolidHit trace",
+		},
+
 		["inh"] =
 		{
 			Handler = HandleConsoleInh,
@@ -302,6 +308,12 @@ g_PluginInfo =
 			HelpString = "Loads the specified chunk into memory",
 		},
 
+		["lostrace"] =
+		{
+			Handler = HandleConsoleLosTrace,
+			HelpString = "Tests a LineOfSight trace",
+		},
+
 		["pluginstats"] =
 		{
 			Handler = HandleConsolePluginStats,

src/Bindings/DeprecatedBindings.cpp

@@ -10,6 +10,7 @@
 #include "../World.h"
 #include "../Entities/Player.h"
 #include "LuaState.h"
+#include "../Tracer.h"
 
 
 
@@ -291,6 +292,47 @@ tolua_lerror:
 
 
 
+/* method: Trace of class  cTracer */
+static int tolua_cTracer_Trace(lua_State * a_LuaState)
+{
+	// Log a deprecation warning with stacktrace:
+	cLuaState S(a_LuaState);
+	LOGWARNING("The function cTracer:Trace is obsolete, use the cLineBlockTracer instead");
+	S.LogStackTrace();
+
+	// Check params:
+	if (
+		!S.CheckParamUserType(1, "cTracer") ||
+		!S.CheckParamUserType(2, "const Vector3<float>", 3) ||
+		!S.CheckParamNumber  (4)
+	)
+	{
+		return 0;
+	}
+
+	// Read params:
+	cTracer * self;
+	Vector3d * start;
+	Vector3d * direction;
+	int distance;
+	bool lineOfSight = false;
+	if (!S.GetStackValues(1, self, start, direction, distance))
+	{
+		LOGWARNING("Cannot retrieve parameters for cTracer::Trace. Expected a cTracer (self), Vector3d, Vector3d, number and optional boolean.");
+		S.LogStackValues();
+		return 0;
+	}
+	S.GetStackValue(5, lineOfSight);
+
+	// Call and push the result:
+	S.Push(self->Trace(*start, *direction, distance, lineOfSight));
+	return 1;
+}
+
+
+
+
+
 /** function: cWorld:SetSignLines */
 static int tolua_cWorld_SetSignLines(lua_State * tolua_S)
 {
@@ -398,6 +440,10 @@ void DeprecatedBindings::Bind(lua_State * tolua_S)
 
 	tolua_function(tolua_S, "StringToMobType", tolua_AllToLua_StringToMobType00);
 
+	tolua_beginmodule(tolua_S, "cTracer");
+		tolua_function(tolua_S, "Trace", tolua_cTracer_Trace);
+	tolua_endmodule(tolua_S);
+
 	tolua_beginmodule(tolua_S, "cWorld");
 		tolua_function(tolua_S, "UpdateSign", tolua_cWorld_SetSignLines);
 	tolua_endmodule(tolua_S);

src/Bindings/ManualBindings.cpp

@@ -2605,7 +2605,7 @@ public:
 	{
 	}
 
-	virtual bool OnNextBlock(int a_BlockX, int a_BlockY, int a_BlockZ, BLOCKTYPE a_BlockType, NIBBLETYPE a_BlockMeta, char a_EntryFace) override
+	virtual bool OnNextBlock(int a_BlockX, int a_BlockY, int a_BlockZ, BLOCKTYPE a_BlockType, NIBBLETYPE a_BlockMeta, eBlockFace a_EntryFace) override
 	{
 		bool res = false;
 		if (!m_Callbacks->CallTableFn(
@@ -2683,6 +2683,202 @@ protected:
 
 
 
+static int tolua_cLineBlockTracer_FirstSolidHitTrace(lua_State * tolua_S)
+{
+	/* Supported function signatures:
+	cLineBlockTracer:FirstSolidHitTrace(World, StartX, StartY, StartZ, EndX, EndY, EndZ) -> bool, [Vector3d, Vector3i, eBlockFace]  // Canonical
+	cLineBlockTracer:FirstSolidHitTrace(World, Start, End) -> bool, [Vector3d, Vector3i, eBlockFace]                                // Canonical
+	cLineBlockTracer.FirstSolidHitTrace(World, StartX, StartY, StartZ, EndX, EndY, EndZ) -> bool, [Vector3d, Vector3i, eBlockFace]
+	cLineBlockTracer.FirstSolidHitTrace(World, Start, End) -> bool, [Vector3d, Vector3i, eBlockFace]
+	*/
+
+	// If the first param is the cLineBlockTracer class, shift param index by one:
+	int idx = 1;
+	tolua_Error err;
+	if (tolua_isusertable(tolua_S, 1, "cLineBlockTracer", 0, &err))
+	{
+		idx = 2;
+	}
+
+	// Check params:
+	cLuaState L(tolua_S);
+	if (
+		!L.CheckParamUserType(idx, "cWorld")
+	)
+	{
+		return 0;
+	}
+
+	if (L.IsParamNumber(idx + 1))
+	{
+		// This is the number variant of the call:
+		if (
+			!L.CheckParamNumber(idx + 1, idx + 6) ||
+			!L.CheckParamEnd(idx + 7)
+		)
+		{
+			return 0;
+		}
+		// Get the params:
+		cWorld * world;
+		double startX, startY, startZ;
+		double endX, endY, endZ;
+		if (!L.GetStackValues(idx, world, startX, startY, startZ, endX, endY, endZ))
+		{
+			LOGWARNING("cLineBlockTracer:FirstSolidHitTrace(): Cannot read parameters, aborting the trace.");
+			L.LogStackTrace();
+			L.LogStackValues("Values on the stack");
+			return 0;
+		}
+		Vector3d hitCoords;
+		Vector3i hitBlockCoords;
+		eBlockFace hitBlockFace;
+		auto isHit = cLineBlockTracer::FirstSolidHitTrace(*world, Vector3d(startX, startY, startZ), Vector3d(endX, endY, endZ), hitCoords, hitBlockCoords, hitBlockFace);
+		L.Push(isHit);
+		if (!isHit)
+		{
+			return 1;
+		}
+		L.Push(hitCoords);
+		L.Push(hitBlockCoords);
+		L.Push(hitBlockFace);
+		return 4;
+	}
+
+	if (L.IsParamUserType(idx + 1, "Vector3<double>"))
+	{
+		// This is the Vector3d-based variant of the call:
+		if (
+			!L.CheckParamUserType(idx + 1, "Vector3<double>", idx + 2) ||
+			!L.CheckParamEnd(idx + 3)
+		)
+		{
+			return 0;
+		}
+		// Get the params:
+		cWorld * world;
+		Vector3d * start;
+		Vector3d * end;
+		if (!L.GetStackValues(idx, world, start, end))
+		{
+			LOGWARNING("cLineBlockTracer:FirstSolidHitTrace(): Cannot read parameters, aborting the trace.");
+			L.LogStackTrace();
+			L.LogStackValues("Values on the stack");
+			return 0;
+		}
+		Vector3d hitCoords;
+		Vector3i hitBlockCoords;
+		eBlockFace hitBlockFace;
+		auto isHit = cLineBlockTracer::FirstSolidHitTrace(*world, start, end, hitCoords, hitBlockCoords, hitBlockFace);
+		L.Push(isHit);
+		if (!isHit)
+		{
+			return 1;
+		}
+		L.Push(hitCoords);
+		L.Push(hitBlockCoords);
+		L.Push(hitBlockFace);
+		return 4;
+	}
+
+	tolua_error(L, "cLineBlockTracer:FirstSolidHitTrace(): Invalid parameters, expected either a set of coords, or two Vector3d's", nullptr);
+	return 0;
+}
+
+
+
+
+
+static int tolua_cLineBlockTracer_LineOfSightTrace(lua_State * tolua_S)
+{
+	/* Supported function signatures:
+	cLineBlockTracer:LineOfSightTrace(World, StartX, StartY, StartZ, EndX, EndY, EndZ, Sight) -> bool  // Canonical
+	cLineBlockTracer:LineOfSightTrace(World, Start, End, Sight) -> bool                                // Canonical
+	cLineBlockTracer.LineOfSightTrace(World, StartX, StartY, StartZ, EndX, EndY, EndZ, Sight) -> bool
+	cLineBlockTracer.LineOfSightTrace(World, Start, End, Sight) -> bool
+	*/
+
+	// If the first param is the cLineBlockTracer class, shift param index by one:
+	int idx = 1;
+	tolua_Error err;
+	if (tolua_isusertable(tolua_S, 1, "cLineBlockTracer", 0, &err))
+	{
+		idx = 2;
+	}
+
+	// Check params:
+	cLuaState L(tolua_S);
+	if (
+		!L.CheckParamUserType(idx, "cWorld")
+	)
+	{
+		return 0;
+	}
+
+	if (L.IsParamNumber(idx + 1))
+	{
+		// This is the number variant of the call:
+		if (
+			!L.CheckParamNumber(idx + 1, idx + 6) ||
+			// Optional param lineOfSight is not checked
+			!L.CheckParamEnd(idx + 8)
+		)
+		{
+			return 0;
+		}
+		// Get the params:
+		cWorld * world;
+		double startX, startY, startZ;
+		double endX, endY, endZ;
+		if (!L.GetStackValues(idx, world, startX, startY, startZ, endX, endY, endZ))
+		{
+			LOGWARNING("cLineBlockTracer:LineOfSightTrace(): Cannot read parameters, aborting the trace.");
+			L.LogStackTrace();
+			L.LogStackValues("Values on the stack");
+			return 0;
+		}
+		int lineOfSight = cLineBlockTracer::losAir | cLineBlockTracer::losWater;
+		L.GetStackValue(idx + 7, lineOfSight);
+		L.Push(cLineBlockTracer::LineOfSightTrace(*world, Vector3d(startX, startY, startZ), Vector3d(endX, endY, endZ), lineOfSight));
+		return 1;
+	}
+
+	if (L.IsParamUserType(idx + 1, "Vector3<double>"))
+	{
+		// This is the Vector3d-based variant of the call:
+		if (
+			!L.CheckParamUserType(idx + 1, "Vector3<double>", idx + 2) ||
+			// Optional param lineOfSight is not checked
+			!L.CheckParamEnd(idx + 4)
+		)
+		{
+			return 0;
+		}
+		// Get the params:
+		cWorld * world;
+		Vector3d * start;
+		Vector3d * end;
+		if (!L.GetStackValues(idx, world, start, end))
+		{
+			LOGWARNING("cLineBlockTracer:LineOfSightTrace(): Cannot read parameters, aborting the trace.");
+			L.LogStackTrace();
+			L.LogStackValues("Values on the stack");
+			return 0;
+		}
+		int lineOfSight = cLineBlockTracer::losAirWater;
+		L.GetStackValue(idx + 7, lineOfSight);
+		L.Push(cLineBlockTracer::LineOfSightTrace(*world, start, end, lineOfSight));
+		return 1;
+	}
+
+	tolua_error(L, "cLineBlockTracer:LineOfSightTrace(): Invalid parameters, expected either a set of coords, or two Vector3d's", nullptr);
+	return 0;
+}
+
+
+
+
+
 static int tolua_cLineBlockTracer_Trace(lua_State * tolua_S)
 {
 	/* Supported function signatures:
@@ -3917,7 +4113,13 @@ void cManualBindings::Bind(lua_State * tolua_S)
 		tolua_endmodule(tolua_S);
 
 		tolua_beginmodule(tolua_S, "cLineBlockTracer");
-			tolua_function(tolua_S, "Trace", tolua_cLineBlockTracer_Trace);
+			tolua_function(tolua_S, "FirstSolidHitTrace", tolua_cLineBlockTracer_FirstSolidHitTrace);
+			tolua_function(tolua_S, "LineOfSightTrace",   tolua_cLineBlockTracer_LineOfSightTrace);
+			tolua_function(tolua_S, "Trace",              tolua_cLineBlockTracer_Trace);
+
+			tolua_constant(tolua_S, "losAir",   cLineBlockTracer::losAir);
+			tolua_constant(tolua_S, "losWater", cLineBlockTracer::losWater);
+			tolua_constant(tolua_S, "losLava",  cLineBlockTracer::losLava);
 		tolua_endmodule(tolua_S);
 
 		tolua_beginmodule(tolua_S, "cLuaWindow");

src/BlockTracer.h

@@ -13,6 +13,12 @@
 
 
 
+#include "Defines.h"
+
+
+
+
+
 // fwd: World.h
 class cWorld;
 
@@ -34,7 +40,7 @@ public:
 		/** Called on each block encountered along the path, including the first block (path start)
 		When this callback returns true, the tracing is aborted.
 		*/
-		virtual bool OnNextBlock(int a_BlockX, int a_BlockY, int a_BlockZ, BLOCKTYPE a_BlockType, NIBBLETYPE a_BlockMeta, char a_EntryFace) = 0;
+		virtual bool OnNextBlock(int a_BlockX, int a_BlockY, int a_BlockZ, BLOCKTYPE a_BlockType, NIBBLETYPE a_BlockMeta, eBlockFace a_EntryFace) = 0;
 
 		/** Called on each block encountered along the path, including the first block (path start), if chunk data is not loaded
 		When this callback returns true, the tracing is aborted.

src/Entities/Entity.cpp

@@ -9,7 +9,7 @@
 #include "../Chunk.h"
 #include "../Simulator/FluidSimulator.h"
 #include "../Bindings/PluginManager.h"
-#include "../Tracer.h"
+#include "../LineBlockTracer.h"
 #include "Player.h"
 #include "Items/ItemHandler.h"
 #include "../FastRandom.h"
@@ -1071,29 +1071,38 @@ void cEntity::HandlePhysics(std::chrono::milliseconds a_Dt, cChunk & a_Chunk)
 	// Get water direction
 	Direction WaterDir = m_World->GetWaterSimulator()->GetFlowingDirection(BlockX, BlockY, BlockZ);
 
-	m_WaterSpeed *= 0.9f;  // Reduce speed each tick
+	m_WaterSpeed *= 0.9;  // Reduce speed each tick
 
 	switch (WaterDir)
 	{
 		case X_PLUS:
+		{
 			m_WaterSpeed.x = 0.2f;
 			m_bOnGround = false;
 			break;
+		}
 		case X_MINUS:
+		{
 			m_WaterSpeed.x = -0.2f;
 			m_bOnGround = false;
 			break;
+		}
 		case Z_PLUS:
+		{
 			m_WaterSpeed.z = 0.2f;
 			m_bOnGround = false;
 			break;
+		}
 		case Z_MINUS:
+		{
 			m_WaterSpeed.z = -0.2f;
 			m_bOnGround = false;
 			break;
-
+		}
-	default:
+		default:
-		break;
+		{
+			break;
+		}
 	}
 
 	if (fabs(m_WaterSpeed.x) < 0.05)
@@ -1110,60 +1119,54 @@ void cEntity::HandlePhysics(std::chrono::milliseconds a_Dt, cChunk & a_Chunk)
 
 	if (NextSpeed.SqrLength() > 0.0f)
 	{
-		cTracer Tracer(GetWorld());
+		Vector3d HitCoords;
-		// Distance traced is an integer, so we round up from the distance we should go (Speed * Delta), else we will encounter collision detection failurse
+		Vector3i HitBlockCoords;
-		int DistanceToTrace = CeilC((NextSpeed * DtSec.count()).SqrLength()) * 2;
+		eBlockFace HitBlockFace;
-		bool HasHit = Tracer.Trace(NextPos, NextSpeed, DistanceToTrace);
+		if (cLineBlockTracer::FirstSolidHitTrace(*GetWorld(), NextPos, NextPos + NextSpeed, HitCoords, HitBlockCoords, HitBlockFace))
-
-		if (HasHit)
 		{
-			// Oh noez! We hit something: verify that the (hit position - current) was smaller or equal to the (position that we should travel without obstacles - current)
+			// Set our position to where the block was hit, minus a bit:
-			// This is because previously, we traced with a length that was rounded up (due to integer limitations), and in the case that something was hit, we don't want to overshoot our projected movement
+			// TODO: The real entity's m_Width should be taken into account here
-			if ((Tracer.RealHit - NextPos).SqrLength() <= (NextSpeed * DtSec.count()).SqrLength())
+			NextPos = HitCoords - NextSpeed.NormalizeCopy() * 0.1;
+			if (HitBlockFace == BLOCK_FACE_YM)
 			{
-				// Block hit was within our projected path
+				// We hit the ground, adjust the position to the top of the block:
-				// Begin by stopping movement in the direction that we hit something. The Normal is the line perpendicular to a 2D face and in this case, stores what block face was hit through either -1 or 1.
+				m_bOnGround = true;
-				// For example: HitNormal.y = -1 : BLOCK_FACE_YM; HitNormal.y = 1 : BLOCK_FACE_YP
+				NextPos.y = HitBlockCoords.y + 1;
-				if (Tracer.HitNormal.x != 0.0f)
+			}
-				{
-					NextSpeed.x = 0.0f;
-				}
-				if (Tracer.HitNormal.y != 0.0f)
-				{
-					NextSpeed.y = 0.0f;
-				}
-				if (Tracer.HitNormal.z != 0.0f)
-				{
-					NextSpeed.z = 0.0f;
-				}
 
-				// Now, set our position to the hit block (i.e. move part way along our intended trajectory)
+			// Avoid movement in the direction of the blockface that has been hit:
-				NextPos.Set(Tracer.RealHit.x, Tracer.RealHit.y, Tracer.RealHit.z);
+			switch (HitBlockFace)
-				NextPos.x += Tracer.HitNormal.x * 0.1;
+			{
-				NextPos.y += Tracer.HitNormal.y * 0.05;
+				case BLOCK_FACE_XM:
-				NextPos.z += Tracer.HitNormal.z * 0.1;
+				case BLOCK_FACE_XP:
-
-				if (Tracer.HitNormal.y == 1.0f)  // Hit BLOCK_FACE_YP, we are on the ground
 				{
-					m_bOnGround = true;
+					NextSpeed.x = 0;
-					NextPos.y = FloorC(NextPos.y);  // we clamp the height to 0 cos otherwise we'll constantly be slightly above the block
+					break;
+				}
+				case BLOCK_FACE_YM:
+				case BLOCK_FACE_YP:
+				{
+					NextSpeed.y = 0;
+					break;
+				}
+				case BLOCK_FACE_ZM:
+				case BLOCK_FACE_ZP:
+				{
+					NextSpeed.z = 0;
+					break;
+				}
+				default:
+				{
+					break;
 				}
 			}
-			else
-			{
-				// We have hit a block but overshot our intended trajectory, move normally, safe in the warm cocoon of knowledge that we won't appear to teleport forwards on clients,
-				// and that this piece of software will come to be hailed as the epitome of performance and functionality in C++, never before seen, and of such a like that will never
-				// be henceforth seen again in the time of programmers and man alike
-				// </&sensationalist>
-				NextPos += (NextSpeed * DtSec.count());
-			}
-		}
-		else
-		{
-			// We didn't hit anything, so move =]
-			NextPos += (NextSpeed * DtSec.count());
 		}
 	}
+	else
+	{
+		// We didn't hit anything, so move =]
+		NextPos += (NextSpeed * DtSec.count());
+	}
 
 	SetPosition(NextPos);
 	SetSpeed(NextSpeed);

src/Entities/ProjectileEntity.cpp

@@ -56,7 +56,7 @@ protected:
 	double m_SlowdownCoeff;
 
 	// cCallbacks overrides:
-	virtual bool OnNextBlock(int a_BlockX, int a_BlockY, int a_BlockZ, BLOCKTYPE a_BlockType, NIBBLETYPE a_BlockMeta, char a_EntryFace) override
+	virtual bool OnNextBlock(int a_BlockX, int a_BlockY, int a_BlockZ, BLOCKTYPE a_BlockType, NIBBLETYPE a_BlockMeta, eBlockFace a_EntryFace) override
 	{
 		/*
 		// DEBUG:

src/Items/ItemBoat.h

@@ -50,7 +50,7 @@ public:
 			{
 			}
 
-			virtual bool OnNextBlock(int a_CBBlockX, int a_CBBlockY, int a_CBBlockZ, BLOCKTYPE a_CBBlockType, NIBBLETYPE a_CBBlockMeta, char a_CBEntryFace) override
+			virtual bool OnNextBlock(int a_CBBlockX, int a_CBBlockY, int a_CBBlockZ, BLOCKTYPE a_CBBlockType, NIBBLETYPE a_CBBlockMeta, eBlockFace a_CBEntryFace) override
 			{
 				if (a_CBBlockType != E_BLOCK_AIR)
 				{

src/Items/ItemBottle.h

@@ -33,7 +33,7 @@ public:
 			{
 			}
 
-			virtual bool OnNextBlock(int a_BlockX, int a_BlockY, int a_BlockZ, BLOCKTYPE a_BlockType, NIBBLETYPE a_BlockMeta, char a_EntryFace) override
+			virtual bool OnNextBlock(int a_BlockX, int a_BlockY, int a_BlockZ, BLOCKTYPE a_BlockType, NIBBLETYPE a_BlockMeta, eBlockFace a_EntryFace) override
 			{
 				if (IsBlockWater(a_BlockType))
 				{

src/Items/ItemBucket.h

@@ -196,7 +196,7 @@ public:
 			{
 			}
 
-			virtual bool OnNextBlock(int a_BlockX, int a_BlockY, int a_BlockZ, BLOCKTYPE a_BlockType, NIBBLETYPE a_BlockMeta, char a_EntryFace) override
+			virtual bool OnNextBlock(int a_BlockX, int a_BlockY, int a_BlockZ, BLOCKTYPE a_BlockType, NIBBLETYPE a_BlockMeta, eBlockFace a_EntryFace) override
 			{
 				if (IsBlockWater(a_BlockType) || IsBlockLava(a_BlockType))
 				{
@@ -241,7 +241,7 @@ public:
 			NIBBLETYPE m_ReplacedBlockMeta;
 			eBlockFace m_EntryFace;
 
-			virtual bool OnNextBlock(int a_CBBlockX, int a_CBBlockY, int a_CBBlockZ, BLOCKTYPE a_CBBlockType, NIBBLETYPE a_CBBlockMeta, char a_CBEntryFace) override
+			virtual bool OnNextBlock(int a_CBBlockX, int a_CBBlockY, int a_CBBlockZ, BLOCKTYPE a_CBBlockType, NIBBLETYPE a_CBBlockMeta, eBlockFace a_CBEntryFace) override
 			{
 				if (a_CBBlockType != E_BLOCK_AIR)
 				{
@@ -250,7 +250,7 @@ public:
 					m_EntryFace = static_cast<eBlockFace>(a_CBEntryFace);
 					if (!cFluidSimulator::CanWashAway(a_CBBlockType) && !IsBlockLiquid(a_CBBlockType))
 					{
-						AddFaceDirection(a_CBBlockX, a_CBBlockY, a_CBBlockZ, static_cast<eBlockFace>(a_CBEntryFace));  // Was an unwashawayable block, can't overwrite it!
+						AddFaceDirection(a_CBBlockX, a_CBBlockY, a_CBBlockZ, a_CBEntryFace);  // Was an unwashawayable block, can't overwrite it!
 					}
 					m_Pos.Set(a_CBBlockX, a_CBBlockY, a_CBBlockZ);  // (Block could be washed away, replace it)
 					return true;  // Abort tracing
@@ -263,7 +263,8 @@ public:
 		Vector3d Start(a_Player->GetEyePosition());
 		Vector3d End(a_Player->GetEyePosition() + a_Player->GetLookVector() * 5);
 
-		// cTracer::Trace returns true when whole line was traversed. By returning true from the callback when we hit something, we ensure that this never happens if liquid could be placed
+		// cLineBlockTracer::Trace() returns true when whole line was traversed. By returning true from the callback when we hit something,
+		// we ensure that this never happens if liquid could be placed
 		// Use this to judge whether the position is valid
 		if (!Tracer.Trace(Start.x, Start.y, Start.z, End.x, End.y, End.z))
 		{

src/Items/ItemLilypad.h

@@ -57,7 +57,7 @@ public:
 			{
 			}
 
-			virtual bool OnNextBlock(int a_CBBlockX, int a_CBBlockY, int a_CBBlockZ, BLOCKTYPE a_CBBlockType, NIBBLETYPE a_CBBlockMeta, char a_CBEntryFace) override
+			virtual bool OnNextBlock(int a_CBBlockX, int a_CBBlockY, int a_CBBlockZ, BLOCKTYPE a_CBBlockType, NIBBLETYPE a_CBBlockMeta, eBlockFace a_CBEntryFace) override
 			{
 				if (IsBlockWater(a_CBBlockType))
 				{

src/LineBlockTracer.cpp

@@ -8,6 +8,7 @@
 #include "Vector3.h"
 #include "World.h"
 #include "Chunk.h"
+#include "BoundingBox.h"
 
 
 
@@ -31,7 +32,7 @@ cLineBlockTracer::cLineBlockTracer(cWorld & a_World, cCallbacks & a_Callbacks) :
 	m_CurrentX(0),
 	m_CurrentY(0),
 	m_CurrentZ(0),
-	m_CurrentFace(0)
+	m_CurrentFace(BLOCK_FACE_NONE)
 {
 }
 
@@ -49,6 +50,97 @@ bool cLineBlockTracer::Trace(cWorld & a_World, cBlockTracer::cCallbacks & a_Call
 
 
 
+bool cLineBlockTracer::LineOfSightTrace(cWorld & a_World, const Vector3d & a_Start, const Vector3d & a_End, int a_Sight)
+{
+	static class LineOfSightCallbacks:
+		public cLineBlockTracer::cCallbacks
+	{
+		bool m_IsAirOpaque;
+		bool m_IsWaterOpaque;
+		bool m_IsLavaOpaque;
+	public:
+		LineOfSightCallbacks(bool a_IsAirOpaque, bool a_IsWaterOpaque, bool a_IsLavaOpaque):
+			m_IsAirOpaque(a_IsAirOpaque),
+			m_IsWaterOpaque(a_IsWaterOpaque),
+			m_IsLavaOpaque(a_IsLavaOpaque)
+		{}
+
+		virtual bool OnNextBlock(int a_BlockX, int a_BlockY, int a_BlockZ, BLOCKTYPE a_BlockType, NIBBLETYPE a_BlockMeta, eBlockFace a_EntryFace) override
+		{
+			switch (a_BlockType)
+			{
+				case E_BLOCK_AIR:              return m_IsAirOpaque;
+				case E_BLOCK_LAVA:             return m_IsLavaOpaque;
+				case E_BLOCK_STATIONARY_LAVA:  return m_IsLavaOpaque;
+				case E_BLOCK_STATIONARY_WATER: return m_IsWaterOpaque;
+				case E_BLOCK_WATER:            return m_IsWaterOpaque;
+				default: return true;
+			}
+		}
+	} callbacks(
+		(a_Sight & losAir) == 0,
+		(a_Sight & losWater) == 0,
+		(a_Sight & losLava) == 0
+	);
+	return Trace(a_World, callbacks, a_Start, a_End);
+}
+
+
+
+
+
+bool cLineBlockTracer::FirstSolidHitTrace(
+	cWorld & a_World,
+	const Vector3d & a_Start, const Vector3d & a_End,
+	Vector3d & a_HitCoords,
+	Vector3i & a_HitBlockCoords, eBlockFace & a_HitBlockFace
+)
+{
+	class cSolidHitCallbacks:
+		public cCallbacks
+	{
+	public:
+		cSolidHitCallbacks(const Vector3d & a_CBStart, const Vector3d & a_CBEnd, Vector3d & a_CBHitCoords, Vector3i & a_CBHitBlockCoords, eBlockFace & a_CBHitBlockFace):
+			m_Start(a_CBStart),
+			m_End(a_CBEnd),
+			m_HitCoords(a_CBHitCoords),
+			m_HitBlockCoords(a_CBHitBlockCoords),
+			m_HitBlockFace(a_CBHitBlockFace)
+		{
+		}
+
+		virtual bool OnNextBlock(int a_BlockX, int a_BlockY, int a_BlockZ, BLOCKTYPE a_BlockType, NIBBLETYPE a_BlockMeta, eBlockFace a_EntryFace) override
+		{
+			if (!cBlockInfo::IsSolid(a_BlockType))
+			{
+				return false;
+			}
+
+			// We hit a solid block, calculate the exact hit coords and abort trace:
+			m_HitBlockCoords.Set(a_BlockX, a_BlockY, a_BlockZ);
+			m_HitBlockFace = a_EntryFace;
+			cBoundingBox bb(a_BlockX, a_BlockX + 1, a_BlockY, a_BlockY + 1, a_BlockZ, a_BlockZ + 1);  // Bounding box of the block hit
+			double LineCoeff = 0;  // Used to calculate where along the line an intersection with the bounding box occurs
+			eBlockFace Face;  // Face hit
+			VERIFY(bb.CalcLineIntersection(m_Start, m_End, LineCoeff, Face));
+			m_HitCoords = m_Start + (m_End - m_Start) * LineCoeff;  // Point where projectile goes into the hit block
+			return true;
+		}
+
+	protected:
+		const Vector3d & m_Start;
+		const Vector3d & m_End;
+		Vector3d & m_HitCoords;
+		Vector3i & m_HitBlockCoords;
+		eBlockFace & m_HitBlockFace;
+	} callbacks(a_Start, a_End, a_HitCoords, a_HitBlockCoords, a_HitBlockFace);
+	return !Trace(a_World, callbacks, a_Start, a_End);
+}
+
+
+
+
+
 bool cLineBlockTracer::Trace(cWorld & a_World, cBlockTracer::cCallbacks &a_Callbacks, double a_StartX, double a_StartY, double a_StartZ, double a_EndX, double a_EndY, double a_EndZ)
 {
 	cLineBlockTracer Tracer(a_World, a_Callbacks);

src/LineBlockTracer.h

@@ -33,6 +33,19 @@ class cLineBlockTracer :
 	typedef cBlockTracer super;
 
 public:
+	enum eLineOfSight
+	{
+		// Bit flags used for LineOfSightTrace's Sight parameter:
+		losAir = 1,    // Can see through air
+		losWater = 2,  // Can see through water
+		losLava = 4,   // Can see through lava
+
+		// Common combinations:
+		losAirWaterLava = losAir | losWater | losLava,
+		losAirWater = losAir | losWater,
+	};
+
+
 	cLineBlockTracer(cWorld & a_World, cCallbacks & a_Callbacks);
 
 	/** Traces one line between Start and End; returns true if the entire line was traced (until OnNoMoreHits()) */
@@ -46,6 +59,24 @@ public:
 	/** Traces one line between Start and End; returns true if the entire line was traced (until OnNoMoreHits()) */
 	static bool Trace(cWorld & a_World, cCallbacks & a_Callbacks, const Vector3d & a_Start, const Vector3d & a_End);
 
+	/** Returns true if the two positions are within line of sight (not obscured by blocks).
+	a_Sight specifies which blocks are considered transparent for the trace, is an OR-combination of eLineOfSight constants. */
+	static bool LineOfSightTrace(cWorld & a_World, const Vector3d & a_Start, const Vector3d & a_End, int a_Sight);
+
+	/** Traces until the first solid block is hit (or until end, whichever comes first.
+	If a solid block was hit, returns true and fills a_HitCoords, a_HitBlockCoords and a_HitBlockFace.
+	If a_End is encountered without hitting any solid block, returns false and doesn't touch a_HitCoords, a_HitBlockCoords nor a_HitBlockFace.
+	a_HitCoords is the exact coords of the hit,
+	a_HitBlockCoords are the coords of the solid block that was hit,
+	a_HitBlockFace is the face of the solid block that was hit. */
+	static bool FirstSolidHitTrace(
+		cWorld & a_World,
+		const Vector3d & a_Start, const Vector3d & a_End,
+		Vector3d & a_HitCoords,
+		Vector3i & a_HitBlockCoords,
+		eBlockFace & a_HitBlockFace
+	);
+
 protected:
 	/** The start point of the trace */
 	double m_StartX, m_StartY, m_StartZ;
@@ -63,7 +94,7 @@ protected:
 	int m_CurrentX, m_CurrentY, m_CurrentZ;
 
 	/** The face through which the current block has been entered */
-	char m_CurrentFace;
+	eBlockFace m_CurrentFace;
 
 
 	/** Adjusts the start point above the world to just at the world's top */

src/Mobs/AggressiveMonster.cpp

@@ -5,7 +5,7 @@
 
 #include "../World.h"
 #include "../Entities/Player.h"
-#include "../Tracer.h"
+#include "../LineBlockTracer.h"
 
 
 
@@ -70,17 +70,20 @@ void cAggressiveMonster::Tick(std::chrono::milliseconds a_Dt, cChunk & a_Chunk)
 		CheckEventSeePlayer(a_Chunk);
 	}
 
-	if (GetTarget() == nullptr)
+	auto target = GetTarget();
+	if (target == nullptr)
 	{
 		return;
 	}
 
-	cTracer LineOfSight(GetWorld());
+	// TODO: Currently all mobs see through lava, but only Nether-native mobs should be able to.
 	Vector3d MyHeadPosition = GetPosition() + Vector3d(0, GetHeight(), 0);
-	Vector3d AttackDirection(GetTarget()->GetPosition() + Vector3d(0, GetTarget()->GetHeight(), 0) - MyHeadPosition);
+	Vector3d TargetPosition = target->GetPosition() + Vector3d(0, target->GetHeight(), 0);
-
+	if (
-
+		TargetIsInRange() &&
-	if (TargetIsInRange() && !LineOfSight.Trace(MyHeadPosition, AttackDirection, static_cast<int>(AttackDirection.Length())) && (GetHealth() > 0.0))
+		cLineBlockTracer::LineOfSightTrace(*GetWorld(), MyHeadPosition, TargetPosition, cLineBlockTracer::losAirWaterLava) &&
+		(GetHealth() > 0.0)
+	)
 	{
 		// Attack if reached destination, target isn't null, and have a clear line of sight to target (so won't attack through walls)
 		Attack(a_Dt);

src/Mobs/Enderman.cpp

@@ -3,7 +3,7 @@
 
 #include "Enderman.h"
 #include "../Entities/Player.h"
-#include "../Tracer.h"
+#include "../LineBlockTracer.h"
 
 
 
@@ -29,9 +29,8 @@ public:
 			return false;
 		}
 
-		Vector3d Direction = m_EndermanPos - a_Player->GetPosition();
+		// Don't check players who are more than SightDistance (64) blocks away
-
+		auto Direction = m_EndermanPos - a_Player->GetPosition();
-		// Don't check players who are more then SightDistance (64) blocks away
 		if (Direction.Length() > m_SightDistance)
 		{
 			return false;
@@ -43,19 +42,16 @@ public:
 			return false;
 		}
 
-
-		Vector3d LookVector = a_Player->GetLookVector();
-		double dot = Direction.Dot(LookVector);
-
-		// 0.09 rad ~ 5 degrees
 		// If the player's crosshair is within 5 degrees of the enderman, it counts as looking
-		if (dot <= cos(0.09))
+		auto LookVector = a_Player->GetLookVector();
+		auto dot = Direction.Dot(LookVector);
+		if (dot <= cos(0.09))  // 0.09 rad ~ 5 degrees
 		{
 			return false;
 		}
 
-		cTracer LineOfSight(a_Player->GetWorld());
+		// TODO: Check if endermen are angered through water in Vanilla
-		if (LineOfSight.Trace(m_EndermanPos, Direction, static_cast<int>(Direction.Length())))
+		if (!cLineBlockTracer::LineOfSightTrace(*a_Player->GetWorld(), m_EndermanPos, a_Player->GetPosition(), cLineBlockTracer::losAirWater))
 		{
 			// No direct line of sight
 			return false;

src/Tracer.h

@@ -35,7 +35,10 @@ public:
 	cTracer(cWorld * a_World);
 	~cTracer();
 
-	/** Determines if a collision occures along a line. Returns true if a collision occurs. */
+	// tolua_end
+
+	/** Determines if a collision occures along a line. Returns true if a collision occurs.
+	Exported manually to add deprecation warnings. */
 	bool Trace(const Vector3f & a_Start, const Vector3f & a_Direction, int a_Distance)
 	{
 		return Trace(a_Start, a_Direction, a_Distance, false);
@@ -44,9 +47,12 @@ public:
 	/** Determines if a collision occures along a line. Returns true if a collision occurs.
 	When a_LineOfSight is true, we don't use the standard collision detection rules. Instead we use
 	the rules for monster vision. E.g. Only water and air do not block vision.
-	a_Distance is the number of iterations (blocks hits) that are tested. */
+	a_Distance is the number of iterations (blocks hits) that are tested.
+	Exported manually to add deprecation warnings. */
 	bool Trace(const Vector3f & a_Start, const Vector3f & a_Direction, int a_Distance, bool a_LineOfSight);
 
+	// tolua_begin
+
 private:
 
 	/** Preps Tracer object for call of Trace function. Only used internally. */

src/World.cpp

@@ -13,6 +13,7 @@
 #include "Generating/ChunkDesc.h"
 #include "SetChunkData.h"
 #include "DeadlockDetect.h"
+#include "LineBlockTracer.h"
 
 // Serializers
 #include "WorldStorage/ScoreboardSerializer.h"
@@ -50,11 +51,6 @@
 #include "Bindings/PluginManager.h"
 #include "Blocks/BlockHandler.h"
 
-#include "Tracer.h"
-
-// DEBUG: Test out the cLineBlockTracer class by tracing a few lines:
-#include "LineBlockTracer.h"
-
 #ifndef _WIN32
 	#include <stdlib.h>
 #endif
@@ -3190,11 +3186,8 @@ bool cWorld::DoWithPlayerByUUID(const AString & a_PlayerUUID, cLambdaPlayerCallb
 
 
 
-// TODO: This interface is dangerous!
 cPlayer * cWorld::FindClosestPlayer(const Vector3d & a_Pos, float a_SightLimit, bool a_CheckLineOfSight)
 {
-	cTracer LineOfSight(this);
-
 	double ClosestDistance = a_SightLimit;
 	cPlayer * ClosestPlayer = nullptr;
 
@@ -3208,22 +3201,23 @@ cPlayer * cWorld::FindClosestPlayer(const Vector3d & a_Pos, float a_SightLimit,
 		Vector3f Pos = (*itr)->GetPosition();
 		double Distance = (Pos - a_Pos).Length();
 
-		if (Distance < ClosestDistance)
+		// If the player is too far, skip them:
+		if (Distance > ClosestDistance)
 		{
-			if (a_CheckLineOfSight)
+			continue;
-			{
-				if (!LineOfSight.Trace(a_Pos, (Pos - a_Pos), static_cast<int>((Pos - a_Pos).Length())))
-				{
-					ClosestDistance = Distance;
-					ClosestPlayer = *itr;
-				}
-			}
-			else
-			{
-				ClosestDistance = Distance;
-				ClosestPlayer = *itr;
-			}
 		}
+
+		// Check LineOfSight, if requested:
+		if (
+			a_CheckLineOfSight &&
+			!cLineBlockTracer::LineOfSightTrace(*this, a_Pos, Pos, cLineBlockTracer::losAirWater)
+		)
+		{
+			continue;
+		}
+
+		ClosestDistance = Distance;
+		ClosestPlayer = *itr;
 	}
 	return ClosestPlayer;
 }