1 files changed, 262 insertions, 0 deletions

diff --git a/src/LineBlockTracer.cpp b/src/LineBlockTracer.cpp
new file mode 100644
index 000000000..9fcbca915
--- /dev/null
+++ b/src/LineBlockTracer.cpp
@@ -0,0 +1,262 @@
+
+// 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 "Vector3d.h"
+#include "World.h"
+#include "Chunk.h"
+
+
+
+
+
+
+cLineBlockTracer::cLineBlockTracer(cWorld & a_World, cCallbacks & a_Callbacks) :
+	super(a_World, a_Callbacks)
+{
+}
+
+
+
+
+
+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.x, a_Start.y, a_Start.z, a_End.x, a_End.y, a_End.z);
+}
+
+
+
+
+
+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);
+	return Tracer.Trace(a_StartX, a_StartY, a_StartZ, a_EndX, a_EndY, a_EndZ);
+}
+
+
+
+
+
+bool cLineBlockTracer::Trace(double a_StartX, double a_StartY, double a_StartZ, double a_EndX, double a_EndY, double a_EndZ)
+{
+	// Initialize the member veriables:
+	m_StartX = a_StartX;
+	m_StartY = a_StartY;
+	m_StartZ = a_StartZ;
+	m_EndX = a_EndX;
+	m_EndY = a_EndY;
+	m_EndZ = a_EndZ;
+	m_DirX = (m_StartX < m_EndX) ? 1 : -1;
+	m_DirY = (m_StartY < m_EndY) ? 1 : -1;
+	m_DirZ = (m_StartZ < m_EndZ) ? 1 : -1;
+	m_CurrentFace = BLOCK_FACE_NONE;
+	
+	// Check the start coords, adjust into the world:
+	if (m_StartY < 0)
+	{
+		if (m_EndY < 0)
+		{
+			// Nothing to trace
+			m_Callbacks->OnNoMoreHits();
+			return true;
+		}
+		FixStartBelowWorld();
+		m_Callbacks->OnIntoWorld(m_StartX, m_StartY, m_StartZ);
+	}
+	else if (m_StartY >= cChunkDef::Height)
+	{
+		if (m_EndY >= cChunkDef::Height)
+		{
+			m_Callbacks->OnNoMoreHits();
+			return true;
+		}
+		FixStartAboveWorld();
+		m_Callbacks->OnIntoWorld(m_StartX, m_StartY, m_StartZ);
+	}
+
+	m_CurrentX = (int)floor(m_StartX);
+	m_CurrentY = (int)floor(m_StartY);
+	m_CurrentZ = (int)floor(m_StartZ);
+	
+	m_DiffX = m_EndX - m_StartX;
+	m_DiffY = m_EndY - m_StartY;
+	m_DiffZ = m_EndZ - m_StartZ;
+	
+	// The actual trace is handled with ChunkMapCS locked by calling our Item() for the specified chunk
+	int BlockX = (int)floor(m_StartX);
+	int BlockZ = (int)floor(m_StartZ);
+	int ChunkX, ChunkZ;
+	cChunkDef::BlockToChunk(BlockX, BlockZ, ChunkX, ChunkZ);
+	return m_World->DoWithChunk(ChunkX, ChunkZ, *this);
+}
+
+
+
+
+
+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 = (double)cChunkDef::Height - 0.00001;
+	CalcXZIntersection(Height, m_StartX, m_StartZ);
+	m_StartY = Height;
+}
+
+
+
+
+
+void cLineBlockTracer::FixStartBelowWorld(void)
+{
+	CalcXZIntersection(0, m_StartX, m_StartZ);
+	m_StartY = 0;
+}
+
+
+
+
+
+void cLineBlockTracer::CalcXZIntersection(double a_Y, double & a_IntersectX, double & a_IntersectZ)
+{
+	double Ratio = (m_StartY - a_Y) / (m_StartY - m_EndY);
+	a_IntersectX = m_StartX + (m_EndX - m_StartX) * Ratio;
+	a_IntersectZ = m_StartZ + (m_EndZ - m_StartZ) * 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;
+	double Coeff = 1;
+	enum eDirection
+	{
+		dirNONE,
+		dirX,
+		dirY,
+		dirZ,
+	} Direction = dirNONE;
+	if (abs(m_DiffX) > EPS)
+	{
+		double DestX = (m_DirX > 0) ? (m_CurrentX + 1) : m_CurrentX;
+		Coeff = (DestX - m_StartX) / m_DiffX;
+		if (Coeff <= 1)
+		{
+			Direction = dirX;
+		}
+	}
+	if (abs(m_DiffY) > EPS)
+	{
+		double DestY = (m_DirY > 0) ? (m_CurrentY + 1) : m_CurrentY;
+		double CoeffY = (DestY - m_StartY) / m_DiffY;
+		if (CoeffY < Coeff)
+		{
+			Coeff = CoeffY;
+			Direction = dirY;
+		}
+	}
+	if (abs(m_DiffZ) > EPS)
+	{
+		double DestZ = (m_DirZ > 0) ? (m_CurrentZ + 1) : m_CurrentZ;
+		double CoeffZ = (DestZ - m_StartZ) / m_DiffZ;
+		if (CoeffZ < Coeff)
+		{
+			Coeff = CoeffZ;
+			Direction = dirZ;
+		}
+	}
+	
+	// Based on the wall hit, adjust the current coords
+	switch (Direction)
+	{
+		case dirX:    m_CurrentX += m_DirX; m_CurrentFace = (m_DirX > 0) ? BLOCK_FACE_XM : BLOCK_FACE_XP; break;
+		case dirY:    m_CurrentY += m_DirY; m_CurrentFace = (m_DirY > 0) ? BLOCK_FACE_YM : BLOCK_FACE_YP; break;
+		case dirZ:    m_CurrentZ += m_DirZ; m_CurrentFace = (m_DirZ > 0) ? BLOCK_FACE_ZM : BLOCK_FACE_ZP; break;
+		case dirNONE: return false;
+	}
+	return true;
+}
+
+
+
+
+
+bool cLineBlockTracer::Item(cChunk * a_Chunk)
+{
+	ASSERT((m_CurrentY >= 0) && (m_CurrentY < cChunkDef::Height));  // This should be provided by FixStartAboveWorld() / FixStartBelowWorld()
+	
+	// This is the actual line tracing loop.
+	bool Finished = false;
+	while (true)
+	{
+		// Report the current block through the callbacks:
+		if (a_Chunk == NULL)
+		{
+			m_Callbacks->OnNoChunk();
+			return false;
+		}
+		if (a_Chunk->IsValid())
+		{
+			BLOCKTYPE BlockType;
+			NIBBLETYPE BlockMeta;
+			int RelX = m_CurrentX - a_Chunk->GetPosX() * cChunkDef::Width;
+			int RelZ = m_CurrentZ - a_Chunk->GetPosZ() * cChunkDef::Width;
+			a_Chunk->GetBlockTypeMeta(RelX, m_CurrentY, RelZ, BlockType, BlockMeta);
+			if (m_Callbacks->OnNextBlock(m_CurrentX, m_CurrentY, m_CurrentZ, BlockType, BlockMeta, m_CurrentFace))
+			{
+				// The callback terminated the trace
+				return false;
+			}
+		}
+		else
+		{
+			if (m_Callbacks->OnNextBlockNoData(m_CurrentX, m_CurrentY, m_CurrentZ, m_CurrentFace))
+			{
+				// The callback terminated the trace
+				return false;
+			}
+		}
+		
+		// Move to next block
+		if (!MoveToNextBlock())
+		{
+			// We've reached the end
+			m_Callbacks->OnNoMoreHits();
+			return true;
+		}
+		
+		// Update the current chunk
+		if (a_Chunk != NULL)
+		{
+			a_Chunk = a_Chunk->GetNeighborChunk(m_CurrentX, m_CurrentZ);
+		}
+		
+		if ((m_CurrentY < 0) || (m_CurrentY >= cChunkDef::Height))
+		{
+			// We've gone out of the world, that's the end of this trace
+			double IntersectX, IntersectZ;
+			CalcXZIntersection(m_CurrentY, IntersectX, IntersectZ);
+			if (m_Callbacks->OnOutOfWorld(IntersectX, m_CurrentY, IntersectZ))
+			{
+				// The callback terminated the trace
+				return false;
+			}
+			m_Callbacks->OnNoMoreHits();
+			return true;
+		}
+	}
+}
+
+
+
+