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refactor(pathfind): Optimize pathfind snippets for higher performance #3198

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8c4ec9c
refactor(pathfind): Optimize appending node to end of the path (#3198)
Skyaero42 Aug 24, 2026
a95690c
refactor(pathfind): Take parents cell's position outside of for-loop …
Skyaero42 Aug 25, 2026
c95c628
refactor(pathfind): Remove redundant isCrusher recomputation for opti…
Skyaero42 Aug 24, 2026
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4 changes: 0 additions & 4 deletions Core/GameEngine/Include/GameLogic/AIPathfind.h
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Original file line number Diff line number Diff line change
Expand Up @@ -106,10 +106,6 @@ class PathNode : public MemoryPoolObject
/// given a list, prepend this node, return new list
PathNode *prependToList( PathNode *list );

/// given a list, append this node, return new list. slow implementation.
/// @todo optimize this
PathNode *appendToList( PathNode *list );

/// given a node, append to this node
void append( PathNode *list );

Expand Down
51 changes: 16 additions & 35 deletions Core/GameEngine/Source/GameLogic/AI/AIPathfind.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -173,28 +173,6 @@ PathNode *PathNode::prependToList( PathNode *list )
return this;
}

//-----------------------------------------------------------------------------------
/// given a list, append this node, return new list. slow implementation.
/// @todo optimize this
PathNode *PathNode::appendToList( PathNode *list )
{
if (list == nullptr)
{
m_next = nullptr;
m_prev = nullptr;
return this;
}

PathNode *tail;
for( tail = list; tail->m_next; tail = tail->m_next )
;

tail->m_next = this;
m_prev = tail;
m_next = nullptr;

return list;
}

//-----------------------------------------------------------------------------------
/// given a node, append new node to this.
Expand Down Expand Up @@ -437,7 +415,14 @@ void Path::appendNode( const Coord3D *pos, PathfindLayerEnum layer )
node->setPosition( pos );
node->setLayer(layer);

m_path = node->appendToList( m_path );
if (m_pathTail)
{
m_pathTail->append(node);
}
else
{
m_path = node->prependToList(nullptr);

@Mauller Mauller Aug 27, 2026 •
edited
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The appendNode code seems wrong, it never does any checking to see if the list is initialised properly and will only update m_pathTail.

it might be worth adding an initial check before this block.

PathNode *node = newInstance(PathNode);

node->setPosition( pos );
node->setLayer(layer);

if (!m_path)
{
 m_path = node;
 m_pathTail = node;

#ifdef CPOP_STARTS_FROM_PREV_SEG
 m_cpopRecentStart = nullptr;
#endif
 return;
}

This block you added can then be simplified to m_pathTail->apend(node);

}

if (m_isOptimized && m_pathTail)
{
Expand Down Expand Up @@ -6184,6 +6169,7 @@ struct ExamineCellsStruct
const LocomotorSet *theLoco;
Bool centerInCell;
Bool isHuman;
Bool isCrusher;
Int radius;
const Object *obj;
PathfindCell *goalCell;
Expand All @@ -6192,10 +6178,9 @@ struct ExamineCellsStruct
/*static*/ Int Pathfinder::examineCellsCallback(Pathfinder* pathfinder, PathfindCell* from, PathfindCell* to, Int to_x, Int to_y, void* userData)
{
ExamineCellsStruct* d = (ExamineCellsStruct*)userData;
Bool isCrusher = d->obj ? d->obj->getCrusherLevel() > 0 : false;
if (d->thePathfinder->m_isTunneling) return 1; // abort.

@Caball009 Caball009 Aug 25, 2026

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Is this check necessary? Could maybe be changed to an assertion given that it's already checked at the call site.

if (from && to) {
if (!d->thePathfinder->validMovementPosition( isCrusher, d->theLoco->getValidSurfaces(), to, from )) {
if (!d->thePathfinder->validMovementPosition( d->isCrusher, d->theLoco->getValidSurfaces(), to, from )) {
return 1;
}
if ( (to->getLayer() == LAYER_GROUND) && !d->thePathfinder->m_zoneManager.isPassable(to_x, to_y) ) {
Expand Down Expand Up @@ -6297,6 +6282,7 @@ Int Pathfinder::examineNeighboringCells(PathfindCell *parentCell, PathfindCell *
info.radius = radius;
info.obj = obj;
info.isHuman = isHuman;
info.isCrusher = isCrusher;
info.goalCell = goalCell;
ICoord2D start, end;
start.x = parentCell->getXIndex();
Expand All @@ -6322,6 +6308,11 @@ Int Pathfinder::examineNeighboringCells(PathfindCell *parentCell, PathfindCell *

UnsignedInt newCostSoFar = 0;

Coord3D fromPos;
fromPos.x = parentCell->getXIndex() * PATHFIND_CELL_SIZE_F ;
fromPos.y = parentCell->getYIndex() * PATHFIND_CELL_SIZE_F ;
fromPos.z = TheTerrainLogic->getGroundHeight(fromPos.x , fromPos.y);
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for( int i=0; i<numNeighbors; i++ )
{
neighborFlags[i] = false;
Expand Down Expand Up @@ -6360,11 +6351,6 @@ Int Pathfinder::examineNeighboringCells(PathfindCell *parentCell, PathfindCell *
// do the gravity check here
if ( locomotorSet.isDownhillOnly() )
{
Coord3D fromPos;
fromPos.x = parentCell->getXIndex() * PATHFIND_CELL_SIZE_F ;
fromPos.y = parentCell->getYIndex() * PATHFIND_CELL_SIZE_F ;
fromPos.z = TheTerrainLogic->getGroundHeight(fromPos.x , fromPos.y);

Coord3D toPos;

@Mauller Mauller Aug 27, 2026

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I wonder if pulling the creation of toPos outside of the loops along with fromPos can help perf a little since we aren't creating and destroying a more complex object constantly.

@Caball009 Caball009 Aug 27, 2026 •
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toPos is updated each iteration due to its dependency on newCellCoord.

@Mauller Mauller Aug 27, 2026

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toPos is updated each iteration due to its dependency on newCellCoord.

i meant just the variable, the assignment to it can be left in the loop.

@Caball009 Caball009 Aug 27, 2026

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Why would that help? It doesn't even have user-defined constructors, so the x y z assignment is the cost of construction.

@Skyaero42 Skyaero42 Aug 27, 2026

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According to Godbolt, the location of the definition doesn't matter.

@Mauller Mauller Aug 29, 2026

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Sometimes not creating variables again every loop can help with performance. But no worries if it does not in this case.

toPos.x = newCellCoord.x * PATHFIND_CELL_SIZE_F ;
toPos.y = newCellCoord.y * PATHFIND_CELL_SIZE_F ;
Expand Down Expand Up @@ -6430,11 +6416,6 @@ Int Pathfinder::examineNeighboringCells(PathfindCell *parentCell, PathfindCell *
}

if (newCell->getType() == PathfindCell::CELL_CLIFF && !newCell->getPinched() ) {
Coord3D fromPos;
fromPos.x = parentCell->getXIndex() * PATHFIND_CELL_SIZE_F ;
fromPos.y = parentCell->getYIndex() * PATHFIND_CELL_SIZE_F ;
fromPos.z = TheTerrainLogic->getGroundHeight(fromPos.x , fromPos.y);

Coord3D toPos;
toPos.x = newCellCoord.x * PATHFIND_CELL_SIZE_F ;
toPos.y = newCellCoord.y * PATHFIND_CELL_SIZE_F ;
Expand Down
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