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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 JsonSerializable; |
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use function min; |
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/** |
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* An item to be packed. |
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* |
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* @author Doug Wright |
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*/ |
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class OrientatedItem implements JsonSerializable |
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{ |
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/** |
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* @var Item |
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*/ |
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protected $item; |
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/** |
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* @var int |
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*/ |
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protected $width; |
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/** |
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* @var int |
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*/ |
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protected $length; |
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/** |
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* @var int |
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*/ |
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protected $depth; |
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/** |
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* @var int |
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*/ |
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protected $surfaceFootprint; |
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/** |
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* @var bool[] |
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*/ |
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protected static $stabilityCache = []; |
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/** |
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* Constructor. |
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*/ |
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public function __construct(Item $item, int $width, int $length, int $depth) |
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{ |
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$this->item = $item; |
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$this->width = $width; |
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$this->length = $length; |
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$this->depth = $depth; |
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$this->surfaceFootprint = $width * $length; |
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} |
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/** |
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* Item. |
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*/ |
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public function getItem(): Item |
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{ |
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return $this->item; |
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} |
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/** |
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* Item width in mm in it's packed orientation. |
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*/ |
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public function getWidth(): int |
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{ |
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return $this->width; |
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} |
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/** |
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* Item length in mm in it's packed orientation. |
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*/ |
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public function getLength(): int |
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{ |
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return $this->length; |
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} |
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/** |
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* Item depth in mm in it's packed orientation. |
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*/ |
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public function getDepth(): int |
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{ |
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return $this->depth; |
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} |
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/** |
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* Calculate the surface footprint of the current orientation. |
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*/ |
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public function getSurfaceFootprint(): int |
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{ |
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return $this->surfaceFootprint; |
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} |
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/** |
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* Is this item stable (low centre of gravity), calculated as if the tipping point is >15 degrees. |
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* |
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* N.B. Assumes equal weight distribution. |
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*/ |
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public function isStable(): bool |
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{ |
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$cacheKey = $this->width . '|' . $this->length . '|' . $this->depth; |
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return static::$stabilityCache[$cacheKey] ?? (static::$stabilityCache[$cacheKey] = atan(min($this->length, $this->width) / ($this->depth ?: 1)) > 0.261); |
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} |
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/** |
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* {@inheritdoc} |
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*/ |
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public function jsonSerialize() |
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{ |
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return [ |
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'item' => $this->item, |
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'width' => $this->width, |
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'length' => $this->length, |
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'depth' => $this->depth, |
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]; |
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} |
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public function __toString(): string |
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{ |
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return $this->width . '|' . $this->length . '|' . $this->depth; |
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} |
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} |
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