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<?php |
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/** |
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* Box packing (3D bin packing, knapsack problem). |
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* |
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* @author Doug Wright |
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*/ |
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declare(strict_types=1); |
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namespace DVDoug\BoxPacker; |
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use Psr\Log\LoggerAwareInterface; |
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use Psr\Log\LoggerAwareTrait; |
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use Psr\Log\NullLogger; |
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use function count; |
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use function max; |
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use function min; |
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/** |
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* Actual packer. |
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* |
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* @author Doug Wright |
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*/ |
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class VolumePacker implements LoggerAwareInterface |
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{ |
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use LoggerAwareTrait; |
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/** |
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* Box to pack items into. |
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* |
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* @var Box |
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*/ |
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protected $box; |
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/** |
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* @var int |
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*/ |
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protected $boxWidth; |
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/** |
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* @var int |
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*/ |
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protected $boxLength; |
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/** |
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* List of items to be packed. |
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* |
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* @var ItemList |
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*/ |
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protected $items; |
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/** |
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* List of items temporarily skipped to be packed. |
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* |
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* @var ItemList |
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*/ |
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protected $skippedItems; |
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/** |
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* Remaining weight capacity of the box. |
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* |
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* @var int |
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*/ |
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protected $remainingWeight; |
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/** |
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* Whether the box was rotated for packing. |
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* |
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* @var bool |
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*/ |
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protected $boxRotated = false; |
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/** |
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* @var PackedLayer[] |
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*/ |
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protected $layers = []; |
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/** |
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* Constructor. |
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* |
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* @param Box $box |
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* @param ItemList $items |
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*/ |
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public function __construct(Box $box, ItemList $items) |
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{ |
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$this->box = $box; |
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$this->items = $items; |
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$this->boxWidth = max($this->box->getInnerWidth(), $this->box->getInnerLength()); |
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$this->boxLength = min($this->box->getInnerWidth(), $this->box->getInnerLength()); |
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$this->remainingWeight = $this->box->getMaxWeight() - $this->box->getEmptyWeight(); |
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$this->skippedItems = new ItemList(); |
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$this->logger = new NullLogger(); |
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// we may have just rotated the box for packing purposes, record if we did |
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if ($this->box->getInnerWidth() !== $this->boxWidth || $this->box->getInnerLength() !== $this->boxLength) { |
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$this->boxRotated = true; |
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} |
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} |
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/** |
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* Pack as many items as possible into specific given box. |
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* |
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* @return PackedBox packed box |
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*/ |
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public function pack(): PackedBox |
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{ |
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$this->logger->debug("[EVALUATING BOX] {$this->box->getReference()}"); |
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while (count($this->items) > 0) { |
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$layerStartDepth = $this->getCurrentPackedDepth(); |
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$this->packLayer($layerStartDepth, $this->boxWidth, $this->boxLength, $this->box->getInnerDepth() - $layerStartDepth); |
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} |
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if ($this->boxRotated) { |
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$this->rotateLayersNinetyDegrees(); |
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} |
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$this->stabiliseLayers(); |
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$this->logger->debug('done with this box'); |
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return new PackedBox($this->box, $this->getPackedItemList()); |
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} |
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/** |
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* Pack items into an individual vertical layer. |
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* |
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* @param int $startDepth |
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* @param int $widthLeft |
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* @param int $lengthLeft |
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* @param int $depthLeft |
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*/ |
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protected function packLayer(int $startDepth, int $widthLeft, int $lengthLeft, int $depthLeft): void |
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{ |
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$this->layers[] = $layer = new PackedLayer(); |
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$prevItem = null; |
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$x = $y = $rowWidth = $rowLength = $layerDepth = 0; |
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while (count($this->items) > 0) { |
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$itemToPack = $this->items->extract(); |
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//skip items that are simply too heavy or too large |
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if (!$this->checkConstraints($itemToPack)) { |
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$this->rebuildItemList(); |
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continue; |
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} |
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$orientatedItem = $this->getOrientationForItem($itemToPack, $prevItem, $this->items, $this->hasItemsLeftToPack(), $widthLeft, $lengthLeft, $depthLeft); |
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if ($orientatedItem instanceof OrientatedItem) { |
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$packedItem = PackedItem::fromOrientatedItem($orientatedItem, $x, $y, $startDepth); |
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$layer->insert($packedItem); |
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$this->remainingWeight -= $orientatedItem->getItem()->getWeight(); |
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$widthLeft -= $orientatedItem->getWidth(); |
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$rowWidth += $orientatedItem->getWidth(); |
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$rowLength = max($rowLength, $orientatedItem->getLength()); |
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$layerDepth = max($layerDepth, $orientatedItem->getDepth()); |
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//allow items to be stacked in place within the same footprint up to current layer depth |
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$stackableDepth = $layerDepth - $orientatedItem->getDepth(); |
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$this->tryAndStackItemsIntoSpace($layer, $prevItem, $this->items, $orientatedItem->getWidth(), $orientatedItem->getLength(), $stackableDepth, $x, $y, $startDepth + $orientatedItem->getDepth()); |
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$x += $orientatedItem->getWidth(); |
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$prevItem = $packedItem; |
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$this->rebuildItemList(); |
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} else { |
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if (count($layer->getItems()) === 0) { // zero items on layer |
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$this->logger->debug("doesn't fit on layer even when empty, skipping for good"); |
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continue; |
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} elseif (count($this->items) > 0) { // skip for now, move on to the next item |
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$this->logger->debug("doesn't fit, skipping for now"); |
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$this->skippedItems->insert($itemToPack); |
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} elseif ($x > 0 && $lengthLeft >= min($itemToPack->getWidth(), $itemToPack->getLength())) { |
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$this->logger->debug('No more fit in width wise, resetting for new row'); |
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$widthLeft += $rowWidth; |
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$lengthLeft -= $rowLength; |
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$y += $rowLength; |
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$x = $rowWidth = $rowLength = 0; |
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$this->rebuildItemList($itemToPack); |
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$prevItem = null; |
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continue; |
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} else { |
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$this->logger->debug('no items fit, so starting next vertical layer'); |
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$this->rebuildItemList($itemToPack); |
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return; |
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} |
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} |
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} |
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} |
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/** |
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* During packing, it is quite possible that layers have been created that aren't physically stable |
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* i.e. they overhang the ones below. |
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* |
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* This function reorders them so that the ones with the greatest surface area are placed at the bottom |
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*/ |
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public function stabiliseLayers(): void |
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{ |
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$stabiliser = new LayerStabiliser(); |
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$this->layers = $stabiliser->stabilise($this->layers); |
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} |
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/** |
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* @param Item $itemToPack |
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* @param PackedItem|null $prevItem |
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* @param ItemList $nextItems |
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* @param bool $isLastItem |
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* @param int $maxWidth |
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* @param int $maxLength |
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* @param int $maxDepth |
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* |
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* @return OrientatedItem|null |
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*/ |
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protected function getOrientationForItem( |
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Item $itemToPack, |
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?PackedItem $prevItem, |
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ItemList $nextItems, |
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bool $isLastItem, |
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int $maxWidth, |
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int $maxLength, |
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int $maxDepth |
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): ?OrientatedItem { |
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$this->logger->debug( |
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"evaluating item {$itemToPack->getDescription()} for fit", |
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[ |
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'item' => $itemToPack, |
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'space' => [ |
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'maxWidth' => $maxWidth, |
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'maxLength' => $maxLength, |
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'maxDepth' => $maxDepth, |
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], |
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] |
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); |
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$prevOrientatedItem = $prevItem ? $prevItem->toOrientatedItem() : null; |
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$orientatedItemFactory = new OrientatedItemFactory($this->box); |
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$orientatedItemFactory->setLogger($this->logger); |
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$orientatedItemDecision = $orientatedItemFactory->getBestOrientation($itemToPack, $prevOrientatedItem, $nextItems, $isLastItem, $maxWidth, $maxLength, $maxDepth); |
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return $orientatedItemDecision; |
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} |
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/** |
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* Figure out if we can stack the next item vertically on top of this rather than side by side |
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* Used when we've packed a tall item, and have just put a shorter one next to it. |
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* |
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* @param PackedLayer $layer |
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* @param PackedItem|null $prevItem |
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* @param ItemList $nextItems |
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* @param int $maxWidth |
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* @param int $maxLength |
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* @param int $maxDepth |
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* @param int $x |
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* @param int $y |
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* @param int $z |
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*/ |
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protected function tryAndStackItemsIntoSpace( |
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PackedLayer $layer, |
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?PackedItem $prevItem, |
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ItemList $nextItems, |
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int $maxWidth, |
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int $maxLength, |
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int $maxDepth, |
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int $x, |
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int $y, |
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int $z |
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): void { |
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while (count($this->items) > 0 && $this->checkNonDimensionalConstraints($this->items->top())) { |
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$stackedItem = $this->getOrientationForItem( |
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$this->items->top(), |
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$prevItem, |
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$nextItems, |
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$this->items->count() === 1, |
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$maxWidth, |
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$maxLength, |
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$maxDepth |
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); |
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if ($stackedItem) { |
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$this->remainingWeight -= $this->items->top()->getWeight(); |
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$layer->insert(PackedItem::fromOrientatedItem($stackedItem, $x, $y, $z)); |
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$this->items->extract(); |
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$maxDepth -= $stackedItem->getDepth(); |
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$z += $stackedItem->getDepth(); |
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} else { |
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break; |
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} |
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} |
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} |
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/** |
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* Check item generally fits into box. |
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* |
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* @param Item $itemToPack |
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* |
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* @return bool |
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*/ |
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protected function checkConstraints( |
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Item $itemToPack |
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): bool { |
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return $this->checkNonDimensionalConstraints($itemToPack) && |
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$this->checkDimensionalConstraints($itemToPack); |
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} |
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/** |
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* As well as purely dimensional constraints, there are other constraints that need to be met |
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* e.g. weight limits or item-specific restrictions (e.g. max <x> batteries per box). |
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* |
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* @param Item $itemToPack |
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* |
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* @return bool |
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*/ |
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protected function checkNonDimensionalConstraints(Item $itemToPack): bool |
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{ |
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$weightOK = $itemToPack->getWeight() <= $this->remainingWeight; |
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if ($itemToPack instanceof ConstrainedItem) { |
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return $weightOK && $itemToPack->canBePackedInBox($this->getPackedItemList(), $this->box); |
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} |
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return $weightOK; |
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} |
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/** |
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* Check the item physically fits in the box (at all). |
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* |
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* @param Item $itemToPack |
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* |
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* @return bool |
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*/ |
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31 |
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protected function checkDimensionalConstraints(Item $itemToPack): bool |
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{ |
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$orientatedItemFactory = new OrientatedItemFactory($this->box); |
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$orientatedItemFactory->setLogger($this->logger); |
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return (bool) $orientatedItemFactory->getPossibleOrientationsInEmptyBox($itemToPack); |
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} |
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/** |
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* Reintegrate skipped items into main list. |
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* |
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* @param Item|null $currentItem item from current iteration |
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*/ |
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31 |
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protected function rebuildItemList(?Item $currentItem = null): void |
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{ |
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31 |
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if (count($this->items) === 0) { |
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$this->items = $this->skippedItems; |
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$this->skippedItems = new ItemList(); |
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} |
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31 |
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if ($currentItem instanceof Item) { |
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$this->items->insert($currentItem); |
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} |
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} |
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358
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/** |
359
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* Swap back width/length of the packed items to match orientation of the box if needed. |
360
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*/ |
361
|
9 |
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protected function rotateLayersNinetyDegrees(): void |
362
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|
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{ |
363
|
9 |
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foreach ($this->layers as $i => $originalLayer) { |
364
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9 |
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$newLayer = new PackedLayer(); |
365
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9 |
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foreach ($originalLayer->getItems() as $item) { |
366
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9 |
|
$packedItem = new PackedItem($item->getItem(), $item->getY(), $item->getX(), $item->getZ(), $item->getLength(), $item->getWidth(), $item->getDepth()); |
367
|
9 |
|
$newLayer->insert($packedItem); |
368
|
|
|
} |
369
|
9 |
|
$this->layers[$i] = $newLayer; |
370
|
|
|
} |
371
|
9 |
|
} |
372
|
|
|
|
373
|
|
|
/** |
374
|
|
|
* Are there items left to pack? |
375
|
|
|
* |
376
|
|
|
* @return bool |
377
|
|
|
*/ |
378
|
30 |
|
protected function hasItemsLeftToPack(): bool |
379
|
|
|
{ |
380
|
30 |
|
return count($this->skippedItems) + count($this->items) === 0; |
381
|
|
|
} |
382
|
|
|
|
383
|
|
|
/** |
384
|
|
|
* Generate a single list of items packed. |
385
|
|
|
* |
386
|
|
|
* @return PackedItemList |
387
|
|
|
*/ |
388
|
31 |
|
protected function getPackedItemList(): PackedItemList |
389
|
|
|
{ |
390
|
31 |
|
$packedItemList = new PackedItemList(); |
391
|
31 |
|
foreach ($this->layers as $layer) { |
392
|
31 |
|
foreach ($layer->getItems() as $packedItem) { |
393
|
31 |
|
$packedItemList->insert($packedItem); |
394
|
|
|
} |
395
|
|
|
} |
396
|
|
|
|
397
|
31 |
|
return $packedItemList; |
398
|
|
|
} |
399
|
|
|
|
400
|
|
|
/** |
401
|
|
|
* Return the current packed depth. |
402
|
|
|
* |
403
|
|
|
* @return int |
404
|
|
|
*/ |
405
|
31 |
|
protected function getCurrentPackedDepth(): int |
406
|
|
|
{ |
407
|
31 |
|
$depth = 0; |
408
|
31 |
|
foreach ($this->layers as $layer) { |
409
|
14 |
|
$depth += $layer->getDepth(); |
410
|
|
|
} |
411
|
|
|
|
412
|
31 |
|
return $depth; |
413
|
|
|
} |
414
|
|
|
} |
415
|
|
|
|