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-rw-r--r--src/Mobs/Path.cpp365
1 files changed, 365 insertions, 0 deletions
diff --git a/src/Mobs/Path.cpp b/src/Mobs/Path.cpp
new file mode 100644
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--- /dev/null
+++ b/src/Mobs/Path.cpp
@@ -0,0 +1,365 @@
+
+#include "Globals.h"
+
+#include <cmath>
+
+#include "Path.h"
+#include "../Chunk.h"
+
+#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 60 // Higher means more CPU load but faster path calculations.
+// The only version which guarantees the shortest path is 0, 0.
+
+enum class eCellStatus {OPENLIST, CLOSEDLIST, NOLIST};
+struct cPathCell
+{
+ Vector3i m_Location; // Location of the cell in the world.
+ int m_F, m_G, m_H; // F, G, H as defined in regular A*.
+ eCellStatus m_Status; // Which list is the cell in? Either non, open, or closed.
+ cPathCell * m_Parent; // Cell's parent, as defined in regular A*.
+ bool m_IsSolid; // Is the cell an air or a solid? Partial solids are currently considered solids.
+};
+
+
+
+
+
+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 Vector3i & a_StartingPoint, const Vector3i & a_EndingPoint, int a_MaxSteps,
+ double a_BoundingBoxWidth, double a_BoundingBoxHeight,
+ int a_MaxUp, int a_MaxDown
+) :
+ m_Destination(a_EndingPoint.Floor()),
+ m_Source(a_StartingPoint.Floor()),
+ m_CurrentPoint(0), // GetNextPoint increments this to 1, but that's fine, since the first cell is always a_StartingPoint
+ m_Chunk(&a_Chunk)
+{
+ // TODO: if src not walkable OR dest not walkable, then abort.
+ // Borrow a new "isWalkable" from ProcessIfWalkable, make ProcessIfWalkable also call isWalkable
+
+ if (GetCell(m_Source)->m_IsSolid || GetCell(m_Destination)->m_IsSolid)
+ {
+ m_Status = ePathFinderStatus::PATH_NOT_FOUND;
+ return;
+ }
+
+ 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_StepsLeft == 0)
+ {
+ FinishCalculation(ePathFinderStatus::PATH_NOT_FOUND);
+ }
+ 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;
+}
+
+
+
+
+
+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())
+ {
+ 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_FENCE_GATE))
+ {
+ 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; // Mobs will always think that the fence is 2 blocks high and therefore won't jump over.
+ }
+
+ return cBlockInfo::IsSolid(BlockType);
+}
+
+
+
+
+
+bool cPath::Step_Internal()
+{
+ cPathCell * CurrentCell = OpenListPop();
+
+ // Path not reachable, open list exauhsted.
+ if (CurrentCell == nullptr)
+ {
+ FinishCalculation(ePathFinderStatus::PATH_NOT_FOUND);
+ ASSERT(m_Status == ePathFinderStatus::PATH_NOT_FOUND);
+ return true;
+ }
+
+ // Path found.
+ if (
+ (CurrentCell->m_Location == m_Destination + Vector3i(0, 0, 1)) ||
+ (CurrentCell->m_Location == m_Destination + Vector3i(1, 0, 0)) ||
+ (CurrentCell->m_Location == m_Destination + Vector3i(-1, 0, 0)) ||
+ (CurrentCell->m_Location == m_Destination + Vector3i(0, 0, -1)) ||
+ (CurrentCell->m_Location == m_Destination + Vector3i(0, -1, 0))
+ )
+ {
+ do
+ {
+ m_PathPoints.push_back(CurrentCell->m_Location); // Populate the cPath with points.
+ CurrentCell = CurrentCell->m_Parent;
+ } while (CurrentCell != nullptr);
+
+ FinishCalculation(ePathFinderStatus::PATH_FOUND);
+ return true;
+ }
+
+ // Calculation not finished yet, process a currentCell by inspecting all neighbors.
+
+ // Check North, South, East, West on all 3 different heights.
+ int i;
+ for (i = -1; i <= 1; ++i)
+ {
+ ProcessIfWalkable(CurrentCell->m_Location + Vector3i(1, i, 0), CurrentCell, 10);
+ ProcessIfWalkable(CurrentCell->m_Location + Vector3i(-1, i, 0), CurrentCell, 10);
+ ProcessIfWalkable(CurrentCell->m_Location + Vector3i(0, i, 1), CurrentCell, 10);
+ ProcessIfWalkable(CurrentCell->m_Location + Vector3i(0, i, -1), CurrentCell, 10);
+ }
+
+ // Check diagonals on mob's height only.
+ int x, z;
+ for (x = -1; x <= 1; x += 2)
+ {
+ for (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::FinishCalculation()
+{
+ for (auto && pair : m_Map)
+ {
+ delete pair.second;
+ }
+
+ m_Map.clear();
+ m_OpenList = std::priority_queue<cPathCell *, std::vector<cPathCell *>, compareHeuristics>{};
+}
+
+
+
+
+
+void cPath::FinishCalculation(ePathFinderStatus a_NewStatus)
+{
+ 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 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);
+ if (!cell->m_IsSolid && GetCell(a_Location + Vector3i(0, -1, 0))->m_IsSolid && !GetCell(a_Location + Vector3i(0, 1, 0))->m_IsSolid)
+ {
+ 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.
+ cPathCell * Cell;
+ if (m_Map.count(a_Location) == 0) // Case 1: Cell is not on any list. We've never checked this cell before.
+ {
+ Cell = new cPathCell();
+ Cell->m_Location = a_Location;
+ m_Map[a_Location] = Cell;
+ Cell->m_IsSolid = IsSolid(a_Location);
+ Cell->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 Cell;
+ }
+ else
+ {
+ return m_Map[a_Location];
+ }
+}