// 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"
static Vector3d CalcXZIntersection(double a_Y, const Vector3d a_Start, const Vector3d a_End)
{
const double Ratio = (a_Start.y - a_Y) / (a_Start.y - a_End.y);
return { a_Start.x + (a_End.x - a_Start.x) * Ratio, a_Y, a_Start.z + (a_End.z - a_Start.z) * Ratio };
}
static Vector3d FixStartAboveWorld(const Vector3d a_Start, const Vector3d a_End)
{
// 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;
return CalcXZIntersection(Height, a_Start, a_End);
}
static Vector3d FixStartBelowWorld(const Vector3d a_Start, const Vector3d a_End)
{
return CalcXZIntersection(0, a_Start, a_End);
}
static eBlockFace MoveToNextBlock(Vector3i & a_CurrentBlock, const Vector3i a_Adjustment, const Vector3d a_Direction, const Vector3d a_Start, const Vector3i a_StepOffset, const eBlockFace a_StepXFace, const eBlockFace a_StepYFace, const eBlockFace a_StepZFace)
{
const auto Coeff = (Vector3d(a_CurrentBlock + a_Adjustment) - a_Start) / a_Direction;
if (Coeff.x <= Coeff.y)
{
if (Coeff.x <= Coeff.z)
{
a_CurrentBlock.x += a_StepOffset.x;
return a_StepXFace;
}
}
else if (Coeff.y <= Coeff.z)
{
a_CurrentBlock.y += a_StepOffset.y;
return a_StepYFace;
}
a_CurrentBlock.z += a_StepOffset.z;
return a_StepZFace;
}
bool LineBlockTracer::Trace(const cChunk & a_Chunk, BlockTracerCallbacks & a_Callbacks, Vector3d a_Start, Vector3d a_End)
{
// Clamp the start coords into the world by advancing them along the line:
if (a_Start.y < 0)
{
if (a_End.y < 0)
{
// Nothing to trace:
a_Callbacks.OnNoMoreHits();
return true;
}
a_Start = FixStartBelowWorld(a_Start, a_End);
a_Callbacks.OnIntoWorld(a_Start);
}
else if (a_Start.y >= cChunkDef::Height)
{
if (a_End.y >= cChunkDef::Height)
{
a_Callbacks.OnNoMoreHits();
return true;
}
a_Start = FixStartAboveWorld(a_Start, a_End);
a_Callbacks.OnIntoWorld(a_Start);
}
const auto EndPosition = a_End.Floor();
const auto Direction = a_End - a_Start;
const bool XPositive = a_Start.x <= a_End.x;
const bool YPositive = a_Start.y <= a_End.y;
const bool ZPositive = a_Start.z <= a_End.z;
const auto StepXFace = XPositive ? BLOCK_FACE_XM : BLOCK_FACE_XP;
const auto StepYFace = YPositive ? BLOCK_FACE_YM : BLOCK_FACE_YP;
const auto StepZFace = ZPositive ? BLOCK_FACE_ZM : BLOCK_FACE_ZP;
const Vector3i Adjustment(XPositive ? 1 : 0, YPositive ? 1 : 0, ZPositive ? 1 : 0);
const Vector3i StepOffset(XPositive ? 1 : -1, YPositive ? 1 : -1, ZPositive ? 1 : -1);
auto Position = a_Start.Floor();
auto Chunk = const_cast<cChunk &>(a_Chunk).GetNeighborChunk(Position.x, Position.z);
// We should always start in a valid chunk:
ASSERT(Chunk != nullptr);
// This is guaranteed by FixStartAboveWorld() / FixStartBelowWorld():
ASSERT(cChunkDef::IsValidHeight(Position));
// This is the actual line tracing loop.
for (;;)
{
if (Position == EndPosition)
{
// We've reached the end
a_Callbacks.OnNoMoreHits();
return true;
}
// The face of the next block the line just entered.
const auto CurrentFace = MoveToNextBlock(Position, Adjustment, Direction, a_Start, StepOffset, StepXFace, StepYFace, StepZFace);
if (!cChunkDef::IsValidHeight(Position))
{
// We've gone out of the world, that's the end of this trace.
if (a_Callbacks.OnOutOfWorld(CalcXZIntersection(static_cast<double>(Position.y), a_Start, a_End)))
{
// The callback terminated the trace
return false;
}
a_Callbacks.OnNoMoreHits();
return true;
}
// Update the current chunk:
Chunk = Chunk->GetNeighborChunk(Position.x, Position.z);
if (Chunk == nullptr)
{
a_Callbacks.OnNoChunk();
return false;
}
// Report the current block through the callbacks:
if (Chunk->IsValid())
{
BLOCKTYPE BlockType;
NIBBLETYPE BlockMeta;
int RelX = Position.x - Chunk->GetPosX() * cChunkDef::Width;
int RelZ = Position.z - Chunk->GetPosZ() * cChunkDef::Width;
Chunk->GetBlockTypeMeta(RelX, Position.y, RelZ, BlockType, BlockMeta);
if (a_Callbacks.OnNextBlock(Position, BlockType, BlockMeta, CurrentFace))
{
// The callback terminated the trace.
return false;
}
}
else if (a_Callbacks.OnNextBlockNoData(Position, CurrentFace))
{
// The callback terminated the trace.
return false;
}
}
}
bool LineBlockTracer::Trace(cWorld & a_World, BlockTracerCallbacks & a_Callbacks, const Vector3d a_Start, const Vector3d a_End)
{
int BlockX = FloorC(a_Start.x);
int BlockZ = FloorC(a_Start.z);
int ChunkX, ChunkZ;
cChunkDef::BlockToChunk(BlockX, BlockZ, ChunkX, ChunkZ);
return a_World.DoWithChunk(ChunkX, ChunkZ, [&a_Callbacks, a_Start, a_End](cChunk & a_Chunk) { return Trace(a_Chunk, a_Callbacks, a_Start, a_End); });
}
bool LineBlockTracer::LineOfSightTrace(cWorld & a_World, const Vector3d & a_Start, const Vector3d & a_End, LineOfSight a_Sight)
{
static class LineOfSightCallbacks:
public BlockTracerCallbacks
{
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 & LineOfSight::Air) == 0,
(a_Sight & LineOfSight::Water) == 0,
(a_Sight & LineOfSight::Lava) == 0
);
return Trace(a_World, callbacks, a_Start, a_End);
}
bool LineBlockTracer::FirstSolidHitTrace(
cWorld & a_World,
const Vector3d & a_Start, const Vector3d & a_End,
Vector3d & a_HitCoords,
Vector3i & a_HitBlockCoords, eBlockFace & a_HitBlockFace
)
{
class cSolidHitCallbacks:
public BlockTracerCallbacks
{
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);
}
