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Version MIT Documentation actions Discord Chat

Flecs is a fast and lightweight Entity Component System that lets you build games and simulations with millions of entities (join the Discord!). Here are some of the framework's highlights:

Flecs Explorer

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What is an Entity Component System?

ECS is a way of organizing code and data that lets you build games that are larger, more complex and are easier to extend. Something is called an ECS when it:

For more information, check the ECS FAQ!

Show me the code!

C99 example:

typedef struct {
  float x, y;
} Position, Velocity;

void Move(ecs_iter_t *it) {
  Position *p = ecs_field(it, Position, 0);
  Velocity *v = ecs_field(it, Velocity, 1);

  for (int i = 0; i < it->count; i++) {
    p[i].x += v[i].x;
    p[i].y += v[i].y;
  }
}

int main(int argc, char *argv[]) {
  ecs_world_t *ecs = ecs_init();

  ECS_COMPONENT(ecs, Position);
  ECS_COMPONENT(ecs, Velocity);

  ECS_SYSTEM(ecs, Move, EcsOnUpdate, Position, Velocity);

  ecs_entity_t e = ecs_insert(ecs, 
    ecs_value(Position, {10, 20}),
    ecs_value(Velocity, {1, 2}));

  while (ecs_progress(ecs, 0)) { }
}

Same example in C++11:

struct Position {
  float x, y;
};

struct Velocity {
  float x, y;
};

int main(int argc, char *argv[]) {
  flecs::world ecs;

  ecs.system<Position, const Velocity>()
    .each([](Position& p, const Velocity& v) {
      p.x += v.x;
      p.y += v.y;
    });

  auto e = ecs.entity()
    .insert([](Position& p, Velocity& v) {
      p = {10, 20};
      v = {1, 2};
    });

  while (ecs.progress()) { }
}

Projects using Flecs

If you have a project you'd like to share, let me know on Discord!

Hytale

Hytale

We knew that we wanted to build Hytale around an Entity-Component-System (ECS). When we analyzed the options, FLECS rose to the top. FLECS provides the backbone of the Hytale Game Engine. Its flexibility has allowed us to build highly varied gameplay while supporting our vision for empowering Creators.

-- Dann Webster, Hypixel studios

Tempest Rising

Tempest Rising

Territory Control 2

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The Forge

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Extermination Shock

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Tome Tumble Tournament

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Sol Survivor

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Equilibrium Engine

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After Sun

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Flecs Demo's

https://github.com/SanderMertens/tower_defense Tower Defense

https://github.com/flecs-hub/city City

Flecs Hub

Flecs Hub is a collection of repositories that show how Flecs can be used to build game systems like input handling, hierarchical transforms and rendering.

ModuleDescription
flecs.components.cglmComponent registration for cglm (math) types
flecs.components.inputComponents that describe keyboard and mouse input
flecs.components.transformComponents that describe position, rotation and scale
flecs.components.physicsComponents that describe physics and movement
flecs.components.geometryComponents that describe geometry
flecs.components.graphicsComponents used for computer graphics
flecs.components.guiComponents used to describe GUI components
flecs.systems.transformHierarchical transforms for scene graphs
flecs.systems.physicsSystems for moving objects and collision detection
flecs.systems.sokolSokol-based renderer
flecs.gameGeneric game systems, like a camera controller

Language bindings

The following language bindings have been developed with Flecs! Note that these are projects built and maintained by helpful community members, and may not always be up to date with the latest commit from master!