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cuberite-2a/src/Mobs/Path.cpp

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C++
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#include "Globals.h"
#include <cmath>
#include "Path.h"
#include "../Chunk.h"
#define JUMP_G_COST 20
#define DISTANCE_MANHATTAN 0 // 1: More speed, a bit less accuracy 0: Max accuracy, less speed.
#define HEURISTICS_ONLY 0 // 1: Much more speed, much less accurate.
#define CALCULATIONS_PER_STEP 10 // Higher means more CPU load but faster path calculations.
// The only version which guarantees the shortest path is 0, 0.
bool compareHeuristics::operator()(cPathCell * & a_Cell1, cPathCell * & a_Cell2)
{
return a_Cell1->m_F > a_Cell2->m_F;
}
/* cPath implementation */
cPath::cPath(
cChunk & a_Chunk,
const Vector3d & a_StartingPoint, const Vector3d & a_EndingPoint, int a_MaxSteps,
double a_BoundingBoxWidth, double a_BoundingBoxHeight,
int a_MaxUp, int a_MaxDown
) :
m_CurrentPoint(0), // GetNextPoint increments this to 1, but that's fine, since the first cell is always a_StartingPoint
m_Chunk(&a_Chunk),
m_BadChunkFound(false)
{
// TODO: if src not walkable OR dest not walkable, then abort.
// Borrow a new "isWalkable" from ProcessIfWalkable, make ProcessIfWalkable also call isWalkable
a_BoundingBoxWidth = 1; // Until we improve physics, if ever.
m_BoundingBoxWidth = CeilC(a_BoundingBoxWidth);
m_BoundingBoxHeight = CeilC(a_BoundingBoxHeight);
m_HalfWidth = a_BoundingBoxWidth / 2;
int HalfWidthInt = FloorC(a_BoundingBoxWidth / 2);
m_Source.x = FloorC(a_StartingPoint.x - HalfWidthInt);
m_Source.y = FloorC(a_StartingPoint.y);
m_Source.z = FloorC(a_StartingPoint.z - HalfWidthInt);
m_Destination.x = FloorC(a_EndingPoint.x - HalfWidthInt);
m_Destination.y = FloorC(a_EndingPoint.y);
m_Destination.z = FloorC(a_EndingPoint.z - HalfWidthInt);
if (GetCell(m_Source)->m_IsSolid || GetCell(m_Destination)->m_IsSolid)
{
m_Status = ePathFinderStatus::PATH_NOT_FOUND;
return;
}
m_NearestPointToTarget = GetCell(m_Source);
m_Status = ePathFinderStatus::CALCULATING;
m_StepsLeft = a_MaxSteps;
ProcessCell(GetCell(a_StartingPoint), nullptr, 0);
m_Chunk = nullptr;
}
cPath::~cPath()
{
if (m_Status == ePathFinderStatus::CALCULATING)
{
FinishCalculation();
}
}
ePathFinderStatus cPath::Step(cChunk & a_Chunk)
{
m_Chunk = &a_Chunk;
if (m_Status != ePathFinderStatus::CALCULATING)
{
return m_Status;
}
if (m_BadChunkFound)
{
FinishCalculation(ePathFinderStatus::PATH_NOT_FOUND);
return m_Status;
}
if (m_StepsLeft == 0)
{
AttemptToFindAlternative();
}
else
{
--m_StepsLeft;
int i;
for (i = 0; i < CALCULATIONS_PER_STEP; ++i)
{
if (Step_Internal()) // Step_Internal returns true when no more calculation is needed.
{
break; // if we're here, m_Status must have changed either to PATH_FOUND or PATH_NOT_FOUND.
}
}
m_Chunk = nullptr;
}
return m_Status;
}
Vector3i cPath::AcceptNearbyPath()
{
ASSERT(m_Status == ePathFinderStatus::NEARBY_FOUND);
m_Status = ePathFinderStatus::PATH_FOUND;
return m_Destination;
}
bool cPath::IsSolid(const Vector3i & a_Location)
{
ASSERT(m_Chunk != nullptr);
auto Chunk = m_Chunk->GetNeighborChunk(a_Location.x, a_Location.z);
if ((Chunk == nullptr) || !Chunk->IsValid())
{
m_BadChunkFound = true;
return true;
}
m_Chunk = Chunk;
BLOCKTYPE BlockType;
NIBBLETYPE BlockMeta;
int RelX = a_Location.x - m_Chunk->GetPosX() * cChunkDef::Width;
int RelZ = a_Location.z - m_Chunk->GetPosZ() * cChunkDef::Width;
m_Chunk->GetBlockTypeMeta(RelX, a_Location.y, RelZ, BlockType, BlockMeta);
if (
(BlockType == E_BLOCK_FENCE) ||
(BlockType == E_BLOCK_OAK_FENCE_GATE) ||
(BlockType == E_BLOCK_NETHER_BRICK_FENCE) ||
((BlockType >= E_BLOCK_SPRUCE_FENCE_GATE) && (BlockType <= E_BLOCK_ACACIA_FENCE))
)
{
// TODO move this out of IsSolid to a proper place.
GetCell(a_Location + Vector3i(0, 1, 0))->m_IsSolid = true; // Mobs will always think that the fence is 2 blocks high and therefore won't jump over.
}
if (BlockType == E_BLOCK_STATIONARY_WATER)
{
GetCell(a_Location + Vector3i(0, -1, 0))->m_IsSolid = true;
}
return cBlockInfo::IsSolid(BlockType);
}
bool cPath::Step_Internal()
{
cPathCell * CurrentCell = OpenListPop();
// Path not reachable.
if (CurrentCell == nullptr)
{
AttemptToFindAlternative();
return true;
}
// Path found.
if (CurrentCell->m_Location == m_Destination)
{
BuildPath();
FinishCalculation(ePathFinderStatus::PATH_FOUND);
return true;
}
// Calculation not finished yet.
// Check if we have a new NearestPoint.
// TODO I don't like this that much, there should be a smarter way.
if ((m_Destination - CurrentCell->m_Location).Length() < 5)
{
if (m_Rand.NextInt(4) == 0)
{
m_NearestPointToTarget = CurrentCell;
}
}
else if (CurrentCell->m_H < m_NearestPointToTarget->m_H)
{
m_NearestPointToTarget = CurrentCell;
}
// process a currentCell by inspecting all neighbors.
// Check North, South, East, West on our height.
ProcessIfWalkable(CurrentCell->m_Location + Vector3i(1, 0, 0), CurrentCell, 10);
ProcessIfWalkable(CurrentCell->m_Location + Vector3i(-1, 0, 0), CurrentCell, 10);
ProcessIfWalkable(CurrentCell->m_Location + Vector3i(0, 0, 1), CurrentCell, 10);
ProcessIfWalkable(CurrentCell->m_Location + Vector3i(0, 0, -1), CurrentCell, 10);
// Check diagonals on XY plane.
// x = -1: west, x = 1: east.
for (int x = -1; x <= 1; x += 2)
{
if (GetCell(CurrentCell->m_Location + Vector3i(x, 0, 0))->m_IsSolid) // If there's a solid our east / west.
{
if (!GetCell(CurrentCell->m_Location + Vector3i(0, 1, 0))->m_IsSolid) // If there isn't a solid above.
{
ProcessIfWalkable(CurrentCell->m_Location + Vector3i(x, 1, 0), CurrentCell, JUMP_G_COST); // Check east-up / west-up.
}
}
else
{
ProcessIfWalkable(CurrentCell->m_Location + Vector3i(x, -1, 0), CurrentCell, 14); // Else check east-down / west-down.
}
}
// Check diagonals on the YZ plane.
for (int z = -1; z <= 1; z += 2)
{
if (GetCell(CurrentCell->m_Location + Vector3i(0, 0, z))->m_IsSolid) // If there's a solid our north / south.
{
if (!GetCell(CurrentCell->m_Location + Vector3i(0, 1, 0))->m_IsSolid) // If there isn't a solid above.
{
ProcessIfWalkable(CurrentCell->m_Location + Vector3i(0, 1, z), CurrentCell, JUMP_G_COST); // Check north-up / south-up.
}
}
else
{
ProcessIfWalkable(CurrentCell->m_Location + Vector3i(0, -1, z), CurrentCell, 14); // Else check north-down / south-down.
}
}
// Check diagonals on the XZ plane. (Normal diagonals, this plane is special because of gravity, etc)
for (int x = -1; x <= 1; x += 2)
{
for (int z = -1; z <= 1; z += 2)
{
// This condition prevents diagonal corner cutting.
if (!GetCell(CurrentCell->m_Location + Vector3i(x, 0, 0))->m_IsSolid && !GetCell(CurrentCell->m_Location + Vector3i(0, 0, z))->m_IsSolid)
{
// This prevents falling of "sharp turns" e.g. a 1x1x20 rectangle in the air which breaks in a right angle suddenly.
if (GetCell(CurrentCell->m_Location + Vector3i(x, -1, 0))->m_IsSolid && GetCell(CurrentCell->m_Location + Vector3i(0, -1, z))->m_IsSolid)
{
ProcessIfWalkable(CurrentCell->m_Location + Vector3i(x, 0, z), CurrentCell, 14); // 14 is a good enough approximation of sqrt(10 + 10).
}
}
}
}
return false;
}
void cPath::AttemptToFindAlternative()
{
if (m_NearestPointToTarget == GetCell(m_Source))
{
FinishCalculation(ePathFinderStatus::PATH_NOT_FOUND);
}
else
{
m_Destination = m_NearestPointToTarget->m_Location;
BuildPath();
FinishCalculation(ePathFinderStatus::NEARBY_FOUND);
}
}
void cPath::BuildPath()
{
cPathCell * CurrentCell = GetCell(m_Destination);
do
{
m_PathPoints.push_back(CurrentCell->m_Location); // Populate the cPath with points.
CurrentCell = CurrentCell->m_Parent;
} while (CurrentCell != nullptr);
}
void cPath::FinishCalculation()
{
m_Map.clear();
m_OpenList = std::priority_queue<cPathCell *, std::vector<cPathCell *>, compareHeuristics>{};
}
void cPath::FinishCalculation(ePathFinderStatus a_NewStatus)
{
if (m_BadChunkFound)
{
a_NewStatus = ePathFinderStatus::PATH_NOT_FOUND;
}
m_Status = a_NewStatus;
FinishCalculation();
}
void cPath::OpenListAdd(cPathCell * a_Cell)
{
a_Cell->m_Status = eCellStatus::OPENLIST;
m_OpenList.push(a_Cell);
#ifdef COMPILING_PATHFIND_DEBUGGER
si::setBlock(a_Cell->m_Location.x, a_Cell->m_Location.y, a_Cell->m_Location.z, debug_open, SetMini(a_Cell));
#endif
}
cPathCell * cPath::OpenListPop() // Popping from the open list also means adding to the closed list.
{
if (m_OpenList.size() == 0)
{
return nullptr; // We've exhausted the search space and nothing was found, this will trigger a PATH_NOT_FOUND or NEARBY_FOUND status.
}
cPathCell * Ret = m_OpenList.top();
m_OpenList.pop();
Ret->m_Status = eCellStatus::CLOSEDLIST;
#ifdef COMPILING_PATHFIND_DEBUGGER
si::setBlock((Ret)->m_Location.x, (Ret)->m_Location.y, (Ret)->m_Location.z, debug_closed, SetMini(Ret));
#endif
return Ret;
}
void cPath::ProcessIfWalkable(const Vector3i & a_Location, cPathCell * a_Parent, int a_Cost)
{
cPathCell * cell = GetCell(a_Location);
int x, y, z;
// Make sure we fit in the position.
for (y = 0; y < m_BoundingBoxHeight; ++y)
{
for (x = 0; x < m_BoundingBoxWidth; ++x)
{
for (z = 0; z < m_BoundingBoxWidth; ++z)
{
if (GetCell(a_Location + Vector3i(x, y, z))->m_IsSolid)
{
return;
}
}
}
}
/*
y = -1;
for (x = 0; x < m_BoundingBoxWidth; ++x)
{
for (z = 0; z < m_BoundingBoxWidth; ++z)
{
if (!GetCell(a_Location + Vector3i(x, y, z))->m_IsSolid)
{
return;
}
}
}
ProcessCell(cell, a_Parent, a_Cost);
*/
// Make sure there's at least 1 piece of solid below us.
bool GroundFlag = false;
y =-1;
for (x = 0; x < m_BoundingBoxWidth; ++x)
{
for (z = 0; z < m_BoundingBoxWidth; ++z)
{
if (GetCell(a_Location + Vector3i(x, y, z))->m_IsSolid)
{
GroundFlag = true;
break;
}
}
}
if (GroundFlag)
{
ProcessCell(cell, a_Parent, a_Cost);
}
}
void cPath::ProcessCell(cPathCell * a_Cell, cPathCell * a_Caller, int a_GDelta)
{
// Case 1: Cell is in the closed list, ignore it.
if (a_Cell->m_Status == eCellStatus::CLOSEDLIST)
{
return;
}
if (a_Cell->m_Status == eCellStatus::NOLIST) // Case 2: The cell is not in any list.
{
// Cell is walkable, add it to the open list.
// Note that non-walkable cells are filtered out in Step_internal();
// Special case: Start cell goes here, gDelta is 0, caller is NULL.
a_Cell->m_Parent = a_Caller;
if (a_Caller != nullptr)
{
a_Cell->m_G = a_Caller->m_G + a_GDelta;
}
else
{
a_Cell->m_G = 0;
}
// Calculate H. This is A*'s Heuristics value.
#if DISTANCE_MANHATTAN == 1
// Manhattan distance. DeltaX + DeltaY + DeltaZ.
a_Cell->m_H = 10 * (abs(a_Cell->m_Location.x-m_Destination.x) + abs(a_Cell->m_Location.y-m_Destination.y) + abs(a_Cell->m_Location.z-m_Destination.z));
#else
// Euclidian distance. sqrt(DeltaX^2 + DeltaY^2 + DeltaZ^2), more precise.
a_Cell->m_H = static_cast<decltype(a_Cell->m_H)>((a_Cell->m_Location - m_Destination).Length() * 10);
#endif
#if HEURISTICS_ONLY == 1
a_Cell->m_F = a_Cell->m_H; // Greedy search. https://en.wikipedia.org/wiki/Greedy_search
#else
a_Cell->m_F = a_Cell->m_H + a_Cell->m_G; // Regular A*.
#endif
OpenListAdd(a_Cell);
return;
}
// Case 3: Cell is in the open list, check if G and H need an update.
int NewG = a_Caller->m_G + a_GDelta;
if (NewG < a_Cell->m_G)
{
a_Cell->m_G = NewG;
a_Cell->m_H = a_Cell->m_F + a_Cell->m_G;
a_Cell->m_Parent = a_Caller;
}
}
cPathCell * cPath::GetCell(const Vector3i & a_Location)
{
// Create the cell in the hash table if it's not already there.
if (m_Map.count(a_Location) == 0) // Case 1: Cell is not on any list. We've never checked this cell before.
{
m_Map[a_Location].m_Location = a_Location;
m_Map[a_Location].m_IsSolid = IsSolid(a_Location);
m_Map[a_Location].m_Status = eCellStatus::NOLIST;
#ifdef COMPILING_PATHFIND_DEBUGGER
#ifdef COMPILING_PATHFIND_DEBUGGER_MARK_UNCHECKED
si::setBlock(a_Location.x, a_Location.y, a_Location.z, debug_unchecked, Cell->m_IsSolid ? NORMAL : MINI);
#endif
#endif
return &m_Map[a_Location];
}
else
{
return &m_Map[a_Location];
}
}
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