Flecs 2.4

[SanderMertens]

Finally! 🎉

Breaking changes
First things first: this release introduces a number of minor breaking changes when compared with the last 2.3.2 release. A non-exhaustive lists of breaking changes is provided here and may be extended later:

• The EcsName component is changed by an EcsIdentifier which is instantiated with EcsName and EcsSymbol tags
• Component destructors are now called on the source component after moving between archetypes
• The ecs_get_object function no longer accepts a component to find an object for a relation, but an index to find the nth object for a relation
• The group_by callback signature have been modified to allow for a context
• The system/query APIs have been updated to a fluent-style builder pattern
• The C++ API no longer uses STL data structures, which in practice means that code that relied on functions returning an std::string may have to be updated.
• Most legacy syntax constructs of the query DSL have been removed
• Removal of CHILDOF and INSTANCEOF roles (use the builtin ChildOf and IsA relations instead)
• include and exclude filter fields are no longer supported (use new filter API)

The highlights of the release are::

• The first feature-complete implementation of entity relationships in any ECS framework
• Removal of dependency on STL data structures, improving compile times & reducing API footprint
• New sokol-style creation functions in C API for entities, components, queries, systems and more
• New fluent-style builder classes in C++ for creation of queries, systems and more
• A new and improved query DSL (domain specific language) with full support for custom relationships
• Improved features for responding to events with triggers & observers
• A novel search data structure for archetypes & relations which speeds up things across the board:
  • Filters evaluate much faster, even though they can be much more complex than before
  • Improved speed of matching tables to queries
  • Operations like ecs_get, ecs_has and get_object are now constant time
  • Improved performance of scope iterators
  • Improved performance of fetching components from base entities & instantiating from base entities
  • Improved performance of ecs_lookup family of functions

This was a large release! A few random facts:

• Flecs met its first sponsorship goal! ❤️
• 380 commits since the last release
• Over 2200 commits since the beginning of the project
• A little more than a year has passed since the first v2.0 release
• Almost a 100 closed PRs and issues:
  • PRs contributed by @randy408, @aganm, @mason-bially, @ikrima, @SpaceIm, @Hexlord, @shanehyde, @Zalron, @nasso and @Wesxdz
  • Issues opened by @SpaceIm, @JonSnowbd, @randy408, @artgreen, @mjjq, @Hexlord, @codylico, @BHolman-LBI, @jtferson, @shanehyde, @cshenton, @Josid88, @jon-turney, @Jarodwr, @HenryFalconerIO, @tedajax, @Zalron, @domdom, @KenthJohan and @zaklaus
  • Thanks everyone! 🙏

I'm skipping the full list of features/improvements/bugs for now as it's a lot, may add it later.

This was the last v2 release. For the next 2 - 3 months the master branch will be used to migrate to the v3 APIs. If you need API stability, stay on this release until the official v3 release. There will be intermediate releases that allow for a more gradual upgrade path to the new v3 APIs.

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This discussion was created from the release Flecs 2.4.