1 files changed, 346 insertions, 0 deletions
diff --git a/src/Physics/Tracers/LineBlockTracer.cpp b/src/Physics/Tracers/LineBlockTracer.cpp
new file mode 100644
index 000000000..49eba9ac8
--- /dev/null
+++ b/src/Physics/Tracers/LineBlockTracer.cpp
@@ -0,0 +1,346 @@
+
+// LineBlockTracer.cpp
+
+// Implements the cLineBlockTracer class representing a cBlockTracer that traces along a straight line between two points
+
+#include "Globals.h"
+#include "LineBlockTracer.h"
+#include "BlockInfo.h"
+#include "World.h"
+#include "Chunk.h"
+#include "BoundingBox.h"
+
+
+
+
+
+cLineBlockTracer::cLineBlockTracer(cWorld & a_World, cCallbacks & a_Callbacks) :
+	Super(a_World, a_Callbacks),
+	m_Start(),
+	m_End(),
+	m_Diff(),
+	m_Dir(),
+	m_Current(),
+	m_CurrentFace(BLOCK_FACE_NONE)
+{
+}
+
+
+
+
+
+bool cLineBlockTracer::Trace(cWorld & a_World, cBlockTracer::cCallbacks & a_Callbacks, const Vector3d a_Start, const Vector3d a_End)
+{
+	cLineBlockTracer Tracer(a_World, a_Callbacks);
+	return Tracer.Trace(a_Start, a_End);
+}
+
+
+
+
+
+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(Vector3i a_BlockPos, 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(Vector3i a_BlockPos, 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 = a_BlockPos;
+			m_HitBlockFace = a_EntryFace;
+			cBoundingBox bb(a_BlockPos, a_BlockPos + Vector3i(1, 1, 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
+			if (!bb.CalcLineIntersection(m_Start, m_End, LineCoeff, Face))
+			{
+				// Math rounding errors have caused the calculation to miss the block completely, assume immediate hit
+				LineCoeff = 0;
+			}
+			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(const Vector3d a_Start, const Vector3d a_End)
+{
+	// Initialize the member veriables:
+	m_Start = a_Start;
+	m_End = a_End;
+	m_Dir.x = (m_Start.x < m_End.x) ? 1 : -1;
+	m_Dir.y = (m_Start.y < m_End.y) ? 1 : -1;
+	m_Dir.z = (m_Start.z < m_End.z) ? 1 : -1;
+	m_CurrentFace = BLOCK_FACE_NONE;
+
+	// Check the start coords, adjust into the world:
+	if (m_Start.y < 0)
+	{
+		if (m_End.y < 0)
+		{
+			// Nothing to trace
+			m_Callbacks->OnNoMoreHits();
+			return true;
+		}
+		FixStartBelowWorld();
+		m_Callbacks->OnIntoWorld(m_Start);
+	}
+	else if (m_Start.y >= cChunkDef::Height)
+	{
+		if (m_End.y >= cChunkDef::Height)
+		{
+			m_Callbacks->OnNoMoreHits();
+			return true;
+		}
+		FixStartAboveWorld();
+		m_Callbacks->OnIntoWorld(m_Start);
+	}
+
+	m_Current = m_Start.Floor();
+
+	m_Diff = m_End -  m_Start;
+
+	// The actual trace is handled with ChunkMapCS locked by calling our ChunkCallback for the specified chunk
+	int BlockX = FloorC(m_Start.x);
+	int BlockZ = FloorC(m_Start.z);
+	int ChunkX, ChunkZ;
+	cChunkDef::BlockToChunk(BlockX, BlockZ, ChunkX, ChunkZ);
+	return m_World->DoWithChunk(ChunkX, ChunkZ, [this](cChunk & a_Chunk) { return ChunkCallback(&a_Chunk); });
+}
+
+
+
+
+
+void cLineBlockTracer::FixStartAboveWorld(void)
+{
+	// We must set the start Y to less than cChunkDef::Height so that it is considered inside the world later on
+	// Therefore we use an EPS-offset from the height, as small as reasonably possible.
+	const double Height = static_cast<double>(cChunkDef::Height) - 0.00001;
+	CalcXZIntersection(Height, m_Start.x, m_Start.z);
+	m_Start.y = Height;
+}
+
+
+
+
+
+void cLineBlockTracer::FixStartBelowWorld(void)
+{
+	CalcXZIntersection(0, m_Start.x, m_Start.z);
+	m_Start.y = 0;
+}
+
+
+
+
+
+void cLineBlockTracer::CalcXZIntersection(double a_Y, double & a_IntersectX, double & a_IntersectZ)
+{
+	double Ratio = (m_Start.y - a_Y) / (m_Start.y - m_End.y);
+	a_IntersectX = m_Start.x + (m_End.x - m_Start.x) * Ratio;
+	a_IntersectZ = m_Start.z + (m_End.z - m_Start.z) * Ratio;
+}
+
+
+
+
+
+bool cLineBlockTracer::MoveToNextBlock(void)
+{
+	// Find out which of the current block's walls gets hit by the path:
+	static const double EPS = 0.00001;
+	enum
+	{
+		dirNONE,
+		dirX,
+		dirY,
+		dirZ,
+	} Direction = dirNONE;
+
+	// Calculate the next YZ wall hit:
+	double Coeff = 1;
+	if (std::abs(m_Diff.x) > EPS)
+	{
+		double DestX = (m_Dir.x > 0) ? (m_Current.x + 1) : m_Current.x;
+		double CoeffX = (DestX - m_Start.x) / m_Diff.x;
+		if (CoeffX <= 1)  // We need to include equality for the last block in the trace
+		{
+			Coeff = CoeffX;
+			Direction = dirX;
+		}
+	}
+
+	// If the next XZ wall hit is closer, use it instead:
+	if (std::abs(m_Diff.y) > EPS)
+	{
+		double DestY = (m_Dir.y > 0) ? (m_Current.y + 1) : m_Current.y;
+		double CoeffY = (DestY - m_Start.y) / m_Diff.y;
+		if (CoeffY <= Coeff)  // We need to include equality for the last block in the trace
+		{
+			Coeff = CoeffY;
+			Direction = dirY;
+		}
+	}
+
+	// If the next XY wall hit is closer, use it instead:
+	if (std::abs(m_Diff.z) > EPS)
+	{
+		double DestZ = (m_Dir.z > 0) ? (m_Current.z + 1) : m_Current.z;
+		double CoeffZ = (DestZ - m_Start.z) / m_Diff.z;
+		if (CoeffZ <= Coeff)  // We need to include equality for the last block in the trace
+		{
+			Direction = dirZ;
+		}
+	}
+
+	// Based on the wall hit, adjust the current coords
+	switch (Direction)
+	{
+		case dirX:    m_Current.x += m_Dir.x; m_CurrentFace = (m_Dir.x > 0) ? BLOCK_FACE_XM : BLOCK_FACE_XP; break;
+		case dirY:    m_Current.y += m_Dir.y; m_CurrentFace = (m_Dir.y > 0) ? BLOCK_FACE_YM : BLOCK_FACE_YP; break;
+		case dirZ:    m_Current.z += m_Dir.z; m_CurrentFace = (m_Dir.z > 0) ? BLOCK_FACE_ZM : BLOCK_FACE_ZP; break;
+		case dirNONE: return false;
+	}
+	return true;
+}
+
+
+
+
+
+bool cLineBlockTracer::ChunkCallback(cChunk * a_Chunk)
+{
+	ASSERT((m_Current.y >= 0) && (m_Current.y < cChunkDef::Height));  // This should be provided by FixStartAboveWorld() / FixStartBelowWorld()
+
+	// This is the actual line tracing loop.
+	for (;;)
+	{
+		// Our caller (DoWithChunk callback) should never give nothing:
+		ASSERT(a_Chunk != nullptr);
+
+		// Move to next block
+		if (!MoveToNextBlock())
+		{
+			// We've reached the end
+			m_Callbacks->OnNoMoreHits();
+			return true;
+		}
+
+		if ((m_Current.y < 0) || (m_Current.y >= cChunkDef::Height))
+		{
+			// We've gone out of the world, that's the end of this trace
+			double IntersectX, IntersectZ;
+			CalcXZIntersection(m_Current.y, IntersectX, IntersectZ);
+			if (m_Callbacks->OnOutOfWorld({IntersectX, double(m_Current.y), IntersectZ}))
+			{
+				// The callback terminated the trace
+				return false;
+			}
+			m_Callbacks->OnNoMoreHits();
+			return true;
+		}
+
+		// Update the current chunk
+		a_Chunk = a_Chunk->GetNeighborChunk(m_Current.x, m_Current.z);
+		if (a_Chunk == nullptr)
+		{
+			m_Callbacks->OnNoChunk();
+			return false;
+		}
+
+		// Report the current block through the callbacks:
+		if (a_Chunk->IsValid())
+		{
+			BLOCKTYPE BlockType;
+			NIBBLETYPE BlockMeta;
+			int RelX = m_Current.x - a_Chunk->GetPosX() * cChunkDef::Width;
+			int RelZ = m_Current.z - a_Chunk->GetPosZ() * cChunkDef::Width;
+			a_Chunk->GetBlockTypeMeta(RelX, m_Current.y, RelZ, BlockType, BlockMeta);
+			if (m_Callbacks->OnNextBlock(m_Current, BlockType, BlockMeta, m_CurrentFace))
+			{
+				// The callback terminated the trace
+				return false;
+			}
+		}
+		else if (m_Callbacks->OnNextBlockNoData(m_Current, m_CurrentFace))
+		{
+			// The callback terminated the trace
+			return false;
+		}
+	}
+}
+
+
+