This repository contains an implementation for the strip packing problem in php.
The strip packing problem optimizes the placing of rectangles in a strip of fixed width and variable length, such that the overall length of the strip is minimised.
The 'Priority Heuristic' algorithm is implemented for the variant in which rotations are allowed and cuts have to follow the guillotine constraint.
note: This algorithm is heuristic which means that the outcome is possibly not the most optimal.
This algorithm is based on the following paper: A priority heuristic for the guillotine rectangular packing problem
@article{zhang2016priority,
title={A priority heuristic for the guillotine rectangular packing problem},
author={Zhang, Defu and Shi, Leyuan and Leung, Stephen CH and Wu, Tao},
journal={Information Processing Letters},
volume={116},
number={1},
pages={15--21},
year={2016},
publisher={Elsevier}
}
The source code is heavily inspired by the python implementation: https://github.com/Mxbonn/strip-packing
However, it uses classes instead of lists for the rectangles and the assigned box positions.
These classes are originally used in a 3D-packing algorithm, hence they are called Box (with width, depth and height)
and PackedBox (with x, y and z).
The 3rd dimension is ignored by this code, hence Box.height and PackedBox.z are not used in this algorithm.
demo/index.php contains an example which can be run in the browser (run php -S localhost:8001 -t demo/)
and direct your browser to http://localhost:8001/
Some visualized results are in the folder demo_images.
examples results:
It is important to realize that the algorithm is an heuristic and will not always find the optimal result.
The authors of the algorithm sort the rectangles internally by width, this is the most optimal for a lot of cases but not always.
Know the difference between heuristic and optimal when using this algorithm.