This project shows a simple hello world application for the reflecs framework. It demonstrates how components are plain C structs, how systems are plain C functions, and how they can be simply registered with reflecs using the ECS_COMPONENT and ECS_SYSTEM macro's. The following code shows how C struct Position is registered as component:

ECS_COMPONENT(world, Position);

It also demonstrates two different kinds of systems. The OnInit system is ran once when a component is added to an entity (there is also a OnDeinit system kind which runs when a component is removed). The OnPeriodic system is ran whenever ecs_progress is invoked. This code shows how a system is registered:

ECS_SYSTEM(world, Move, EcsPeriodic, Position, Speed);

Finally, the example shows how to efficiently add components to an entity using ecs_stage and ecs_commit. Components in reflecs are stored in tables. Tables are automatically created for every combination of components that is found on entities. To prevent moving an entity between tables while adding multiple components, components are first staged, and only inserted into a table when ecs_commit is called. Example from code:

EcsHandle e = ecs_new(world);
ecs_stage(world, e, Position_h);
ecs_stage(world, e, Speed_h);
ecs_commit(world, e);