slt_pack

A simple incremental C++ bin packer

Documenation

Simple usage

Create a packer by instantiating slt::RectPacker2D with a bin size as constructor argument.
Call pack() for every rect you want to pack. (If you are doing packing in batches, it's best to call pack with larger rects first)

Memory usage

slt::RectPacker2D needs to do a bit of dymanic memory allocation in order to keep track of available space. If you want control over this, you can provide it with a custom rebindable allocator.

Custom packing heuristics

You can change the packing heuristics used by the packer if you want by passing a functor to the pack() call. The DefaultRectScorer function at the top of rect_pack.h should provide a good template to follow. Just remember that lower scores are better.

Increasing the bin size after creation.

You can add more storage to the packer by invoking addFreeRect(). This can be done in order to "dealocate" regions that have been previosuly returned by pack(), or increase the overall storage.

Usage Example:

#include "slt/rect_pack.h"

#include <algorithm>
#include <iostream>
#include <vector>

int main() {
  using packer_t = slt::RectPacker2D<int>;
  
  std::vector<packer_t::Vec> rects_to_pack;
  
  rects_to_pack.emplace_back({2,2});
  rects_to_pack.emplace_back({4,2});
  rects_to_pack.emplace_back({3,1});

  //Larger rects first
  std::sort(rects_to_pack.begin(), rects_to_pack.end(), std::greater<packer_t::Vec>);

  packer_t packer({ 12, 12 });
  for(auto const& r : rects_to_pack) {
    packer_t result;
    bool success = packer.pack(r, result);
    if(success) {
      std::cout << "packed at: " << result.pos[0] <<  '-' << result.pos[1];
      if(result.flipped) {
        std::cout << " (flipped)";
      }
      std::cout << std::endl;
    }
  }

  return 0;
}