public function compute(Node $a, Node $b)
{
$f = sqrt(2) - 1;
$dx = abs($a->getX() - $b->getX());
$dy = abs($a->getY() - $b->getY());
return $dx < $dy ? $f * $dx + $dy : $f * $dy + $dx;
}
public function computePath(Node $source, Node $target)
{
if (!$this->grid instanceof NodeGrid) {
throw new \RuntimeException('Invalid Grid');
}
$priorityQueue = new NodePriorityQueueMin();
$distanceMap = new NodeMap();
$previousMap = new NodeMap();
$priorityQueue->insert($source, 0);
$distanceMap->insert($source, 0);
while (!$priorityQueue->isEmpty()) {
$node = $priorityQueue->extract();
if ($node->getId() === $target->getId()) {
return new NodePath($previousMap->lookupFrom($node));
}
$neighbors = $this->grid->getWalkableNeighbors($node);
foreach ($neighbors as $neighbor) {
$alternativeDistance = $distanceMap->lookup($node) + $this->distance->compute($node, $neighbor);
if (!$distanceMap->exists($neighbor) || $alternativeDistance < $distanceMap->lookup($neighbor)) {
$priorityQueue->insert($neighbor, $alternativeDistance);
$distanceMap->insert($neighbor, $alternativeDistance);
$previousMap->insert($neighbor, $node);
}
}
}
return array();
// no path found
}
public function computePath(Node $source, Node $target)
{
if (!$this->grid instanceof NodeGrid) {
throw new \RuntimeException('Invalid Grid');
}
$fScorePriorityQueue = new NodePriorityQueueMin();
$gScoreMap = new NodeMap();
$openedMap = new NodeMap();
$closedMap = new NodeMap();
$previousMap = new NodeMap();
$fScorePriorityQueue->insert($source, 0);
$gScoreMap->insert($source, 0);
$openedMap->insert($source);
while (!$fScorePriorityQueue->isEmpty()) {
$node = $fScorePriorityQueue->extract();
$closedMap->insert($node);
if ($node->getId() === $target->getId()) {
return new NodePath($previousMap->lookupFrom($node));
}
$neighbors = $this->grid->getWalkableNeighbors($node);
foreach ($neighbors as $neighbor) {
if ($closedMap->exists($neighbor)) {
continue;
}
$gScore = $gScoreMap->lookup($node) + $this->distance->compute($node, $neighbor);
if (!$openedMap->exists($neighbor) || $gScore < $gScoreMap->lookup($neighbor)) {
$fScore = $gScore + $this->heuristic->compute($node, $target);
$fScorePriorityQueue->insert($neighbor, $fScore);
$gScoreMap->insert($neighbor, $gScore);
$openedMap->insert($neighbor);
$previousMap->insert($neighbor, $node);
}
}
}
// no path found
return array();
}
public function compute(Node $a, Node $b)
{
$dx = abs($a->getX() - $b->getX());
$dy = abs($a->getY() - $b->getY());
return max($dx, $dy);
}
public function compute(Node $a, Node $b)
{
$dx = abs($a->getX() - $b->getX());
$dy = abs($a->getY() - $b->getY());
return sqrt($dx * $dx + $dy * $dy);
}
