Not packing optimally about boxpacker

[dvdoug]

Hello

So it seems your specific example here is something of an edge case as far as the current algorithm is concerned - as you can see in the debug log, the algorithm starts off by deciding that a "rotated" packing is the best way to fit each item which does seem correct. However, after the first few items are packed, the space left is a 165x165 square, and at that point the heuristics switch to deciding that an "unrotated" packing is the best use of the available space (the packing is done item-by-item, with little consideration of what comes next).

I spent some time earlier trying out an approach that would ensure more consistency in orientation of consistently sized items like in your testcase, however although that improved the packing in this case, and in some of my other test samples, it regressed the efficiency in more than it improved.

I'll keep this open though and will try out and figure out a way to detect when consistent orientation is likely to help, and when it won't.

[RobinTail]

Hello. I found that VolumePacker's algorithm does not correctly calculate layer's remaining space. Here is an example. Box size: 23.6875 x 11.75 x 3 inch. Trying to pack 9 items with size: 6.5 x 3.75 x 3 inch. So, this is 2D packaging by the only layer. As you can see, this box could perfectly fit 9 unrotated items: 6.5" x 3pcs = 19.5" < 23.6875", and 3.75" x 3pcs = 11.25" < 11.75", so 3pcs x 3pcs = 9pcs.
I'm attaching VolumePacker log and picture of packaging process. The fourth item packed rotated and on the next step the remaining layer's space calculated incorrectly (by remaining width — 5.25).

[dvdoug]

@RobinTail, just to clarify, the maths seems right here to me - having decided (perhaps non-optimally) to pack box 4 rotated alongside box 3 instead of starting a new row, the space left for row 2 is indeed (11.25-6.5)=5.25

[dvdoug]

@RobinTail, can I check what version of BoxPacker you're using? I created a testcase for this and ran it against 1.5.2 and it produced a 3x3 output like you were expecting.

[2016-05-30 15:57:29] log.INFO: added box Box [] []
[2016-05-30 15:57:29] log.INFO: added 9 x Item [] []
[2016-05-30 15:57:29] log.DEBUG: [EVALUATING BOX] Box [] []
[2016-05-30 15:57:29] log.DEBUG: evaluating item Item [] []
[2016-05-30 15:57:29] log.DEBUG: remaining width: 23.6875, length: 11.75, depth: 3 [] []
[2016-05-30 15:57:29] log.DEBUG: layerWidth: 0, layerLength: 0, layerDepth: 0 [] []
[2016-05-30 15:57:29] log.DEBUG: fits (better) unrotated [] []
[2016-05-30 15:57:29] log.DEBUG: evaluating item Item [] []
[2016-05-30 15:57:29] log.DEBUG: remaining width: 23.6875, length: 8, depth: 3 [] []
[2016-05-30 15:57:29] log.DEBUG: layerWidth: 6.5, layerLength: 3.75, layerDepth: 3 [] []
[2016-05-30 15:57:29] log.DEBUG: fits (better) unrotated [] []
[2016-05-30 15:57:29] log.DEBUG: evaluating item Item [] []
[2016-05-30 15:57:29] log.DEBUG: remaining width: 23.6875, length: 4.25, depth: 3 [] []
[2016-05-30 15:57:29] log.DEBUG: layerWidth: 6.5, layerLength: 7.5, layerDepth: 3 [] []
[2016-05-30 15:57:29] log.DEBUG: fits (better) unrotated [] []
[2016-05-30 15:57:29] log.DEBUG: evaluating item Item [] []
[2016-05-30 15:57:29] log.DEBUG: remaining width: 23.6875, length: 0.5, depth: 3 [] []
[2016-05-30 15:57:29] log.DEBUG: layerWidth: 6.5, layerLength: 11.25, layerDepth: 3 [] []
[2016-05-30 15:57:29] log.DEBUG: No more fit in lengthwise, resetting for new row [] []
[2016-05-30 15:57:29] log.DEBUG: evaluating item Item [] []
[2016-05-30 15:57:29] log.DEBUG: remaining width: 17.1875, length: 11.75, depth: 3 [] []
[2016-05-30 15:57:29] log.DEBUG: layerWidth: 0, layerLength: 0, layerDepth: 3 [] []
[2016-05-30 15:57:29] log.DEBUG: fits (better) unrotated [] []
[2016-05-30 15:57:29] log.DEBUG: evaluating item Item [] []
[2016-05-30 15:57:29] log.DEBUG: remaining width: 17.1875, length: 8, depth: 3 [] []
[2016-05-30 15:57:29] log.DEBUG: layerWidth: 6.5, layerLength: 3.75, layerDepth: 3 [] []
[2016-05-30 15:57:29] log.DEBUG: fits (better) unrotated [] []
[2016-05-30 15:57:29] log.DEBUG: evaluating item Item [] []
[2016-05-30 15:57:29] log.DEBUG: remaining width: 17.1875, length: 4.25, depth: 3 [] []
[2016-05-30 15:57:29] log.DEBUG: layerWidth: 6.5, layerLength: 7.5, layerDepth: 3 [] []
[2016-05-30 15:57:29] log.DEBUG: fits (better) unrotated [] []
[2016-05-30 15:57:29] log.DEBUG: evaluating item Item [] []
[2016-05-30 15:57:29] log.DEBUG: remaining width: 17.1875, length: 0.5, depth: 3 [] []
[2016-05-30 15:57:29] log.DEBUG: layerWidth: 6.5, layerLength: 11.25, layerDepth: 3 [] []
[2016-05-30 15:57:29] log.DEBUG: No more fit in lengthwise, resetting for new row [] []
[2016-05-30 15:57:29] log.DEBUG: evaluating item Item [] []
[2016-05-30 15:57:29] log.DEBUG: remaining width: 10.6875, length: 11.75, depth: 3 [] []
[2016-05-30 15:57:29] log.DEBUG: layerWidth: 0, layerLength: 0, layerDepth: 3 [] []
[2016-05-30 15:57:29] log.DEBUG: fits (better) unrotated [] []
[2016-05-30 15:57:29] log.DEBUG: evaluating item Item [] []
[2016-05-30 15:57:29] log.DEBUG: remaining width: 10.6875, length: 8, depth: 3 [] []
[2016-05-30 15:57:29] log.DEBUG: layerWidth: 6.5, layerLength: 3.75, layerDepth: 3 [] []
[2016-05-30 15:57:29] log.DEBUG: fits (better) unrotated [] []
[2016-05-30 15:57:29] log.DEBUG: evaluating item Item [] []
[2016-05-30 15:57:29] log.DEBUG: remaining width: 10.6875, length: 4.25, depth: 3 [] []
[2016-05-30 15:57:29] log.DEBUG: layerWidth: 6.5, layerLength: 7.5, layerDepth: 3 [] []
[2016-05-30 15:57:29] log.DEBUG: fits (better) unrotated [] []
[2016-05-30 15:57:29] log.DEBUG: done with this box [] []
[2016-05-30 15:57:29] log.INFO: packing completed, 1 boxes [] []

[RobinTail]

@dvdoug i'm on commit ca74d34
Also, i'm using Length as the longest dimension for Box and Item.

[RobinTail]

@dvdoug I've downloaded version 1.5.2 and wrote my own test :)
Here is the code inside PackerTest.php, that fails on version 1.5.2

public function testRobin() {
    $box = new TestBox('Large Flat Rate Game Box', 11.75, 23.6875, 3, 0, 11.75, 23.6875, 3, 70);
    $item = new TestItem('Coffee', 3.75, 6.5, 3, 1.26);
    $packer = new Packer();
    $packer->addBox($box);
    $packer->addItem($item, 9);
    $result = $packer->pack();
    self::assertEquals(count($result), 1);
}

[dvdoug]

@RobinTail, FYI this works as you expect in this case if you swap the dimensions of the coffee around - 6.5x3.75. However, a global assumption in packing that length/width is the smaller/bigger dimension seems to be harmful to efficiency on a wider scale.

I need to ponder....