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cuberite-2a/src/LineBlockTracer.cpp

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// LineBlockTracer.cpp
// Implements the cLineBlockTracer class representing a cBlockTracer that traces along a straight line between two points
#include "Globals.h"
#include "LineBlockTracer.h"
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#include "Vector3.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;
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if (std::abs(m_DiffX) > EPS)
{
double DestX = (m_DirX > 0) ? (m_CurrentX + 1) : m_CurrentX;
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Coeff = (DestX - m_StartX) / m_DiffX;
if (Coeff <= 1)
{
Direction = dirX;
}
}
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if (std::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;
}
}
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if (std::abs(m_DiffZ) > EPS)
{
double DestZ = (m_DirZ > 0) ? (m_CurrentZ + 1) : m_CurrentZ;
double CoeffZ = (DestZ - m_StartZ) / m_DiffZ;
if (CoeffZ < Coeff)
{
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.
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for (;;)
{
// Report the current block through the callbacks:
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if (a_Chunk == nullptr)
{
m_Callbacks->OnNoChunk();
return false;
}
// Move to next block
if (!MoveToNextBlock())
{
// We've reached the end
m_Callbacks->OnNoMoreHits();
return true;
}
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;
}
// Update the current chunk
a_Chunk = a_Chunk->GetNeighborChunk(m_CurrentX, m_CurrentZ);
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if (a_Chunk == nullptr)
{
m_Callbacks->OnNoChunk();
return false;
}
if (a_Chunk->IsValid())
{
BLOCKTYPE BlockType;
NIBBLETYPE BlockMeta;
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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;
}
}
}