Gearecs

A lightweight Entity Component System library for C game development, built on top of raylib. Gearecs provides a modern, data-oriented architecture for creating efficient and scalable 2D games.

Gearecs implements the ECS pattern, which separates data from logic:

• Entities: Unique identifiers representing game objects
• Components: Data containers (position, velocity, health, etc.)
• Systems: Functions that process entities with specific components

Enables highly performant, cache-friendly code with excellent modularity and reusability.

Features

• ECS Architecture - Flexible, data-driven design pattern
• Built-in Components - Transform2, RigidBody, Collider, Sprite, and more
• Physics Simulation - Complete collision detection, forces, gravity, and rigid body dynamics
• Hierarchy Relationships - Parent-child relationships for complex object structures
• Scripting - Entity-specific logic across multiple execution layers
• Scene Management - Automatic scene setup with camera and generic game loop
• Multi-platform Support - Linux, Windows, Web...
• Raylib Integration - Seamless rendering and input handling

Quick Start

Installation

CMake

cmake_minimum_required(VERSION 3.25)
set(CMAKE_C_STANDARD 11)

include(FetchContent)
set(FETCHCONTENT_QUIET FALSE)
set(GEARECS_BUILD_EXAMPLES OFF CACHE BOOL "" FORCE)
FetchContent_Declare(
  gearecs
  GIT_REPOSITORY https://github.com/fals3bool/gearecs.git
  GIT_TAG main
)
FetchContent_MakeAvailable(gearecs)

Basic Example

#include <gearecs.h>

#define SCREEN_WIDTH 800
#define SCREEN_HEIGHT 450
#define SPEED 900

void MoveScript(ECS *ecs, Entity self) {
  RigidBody *rb = GetComponent(ecs, self, RigidBody);
  Transform2 *t = GetComponent(ecs, self, Transform2);
  
  if (IsMouseButtonDown(MOUSE_BUTTON_LEFT)) {
    Vector2 direction = {cosf(t->rotation), sinf(t->rotation)};
    ApplyImpulse(rb, Vector2Scale(direction, SPEED));
  }

  Camera2D *cam = GetComponent(ecs, 0, Camera2D);
  Vector2 mouseWorld = GetScreenToWorld2D(GetMousePosition(), *cam);
  Vector2 mouseDirection = {
    mouseWorld.x - t->position.x, 
    mouseWorld.y - t->position.y
  };
  t->rotation = atan2f(mouseDirection.y, mouseDirection.x);
}

int main(void) {
  // Raylib window and camera
  InitWindow(SCREEN_WIDTH, SCREEN_HEIGHT, "GearECS Example");
  Camera2D camera = {
      {SCREEN_WIDTH / 2.0f, SCREEN_HEIGHT / 2.0f}, {0, 0}, 0, 1.0f};

  // Registry
  ECS *world = EcsWorld(1024, camera);

  // Player entity
  Texture tex = LoadTexture("res/example.png");
  Entity player = EcsEntity(world, "Player");
  AddComponent(world, player, Sprite, 
    {tex, {0, 0, 32, 32}, WHITE});
  AddComponent(world, player, RigidBody, 
    RigidBodyKinematic(50, 1.5f));
  AddScript(world, player, MoveScript, EcsOnFixedUpdate);

  // Main game loop
  EcsLoop(world);
  
  // Cleanup
  EcsFree(world);
  UnloadTexture(tex);
  CloseWindow();
  return 0;
}