Entity Component System (ECS) Demo

Introduction

Hello, comrades! This is my training project, it consists of two parts : ECS and OpenGL based Dummy-Engine.
Main purpose of this project - create ECS with minimal perfomance overhead (ha-ha-ha), because of this I preferred static polymorphism (template magic), flat memory collections and hierarchies avoidance.
Since this project is training there are some disadvantages:

• Project isn't well tested
• I tried to implement cross-platform code, but it isn't configured for Linux build
• There are may be strange names and architecture decisions
• Isn't thread safe

Requirements and external dependencies

ECS part:

• C++17 compiler (repository includes MS Visual Studio 2019 project and CMake for msvc)

Dummy-Engine part:

• GLFW (https://www.glfw.org/). In project global variable GLFW_DIR is used.
• GLM (https://github.com/g-truc/glm). In project global variable GLM_DIR is used.
• OpenGL extensions (https://www.khronos.org/registry/OpenGL/index_gl.php). In project global variable OPENGL_EXT_DIR is used.

Entity Component System (ECS) part

Necessary files:

• ./ecs/ECS.h
• ./utils/Utils.h

Important classes:

• EntityManager - factory of entities, return Entity ID (EntityIdType)
• ComponentCollection<_Type> - components factory-collection of _Type, contains Utils::ChunkBuffer and Utils::ChunkTable
• ComponentManager<_Types> - aggregates a lot of ComponentCollection from _Types

Dummy Engine part

Necessary files: all projects files are necessary

Important classes:

• BaseSystem and it's Inheritances
  All Systems must be inherited from BaseSystem.
  There are two kinds of systems: Engine (./engine folder) and User (./user_logic folder).
  System can have next methods:

   // Methods per entity
   void init(SystemsOrders::Init::_ORDER_, const ECS::EntityIdType entity_id);
   void update(SystemsOrders::Update::_ORDER_, const ECS::EntityIdType entity_id);
   void postUpdate(SystemsOrders::PostUpdate::_ORDER_, const ECS::EntityIdType entity_id);
   void destroy(SystemsOrders::Destroy::_ORDER_, const ECS::EntityIdType entity_id);
   // Common methods, called once per frame (except init(...) and destroy(...)
   void init(SystemsOrders::Init::_ORDER_);
   void update(SystemsOrders::Update::_ORDER_);
   void postUpdate(SystemsOrders::PostUpdate::_ORDER_);
   void destroy(SystemsOrders::Destroy::_ORDER_);

• Common::Engine (engine/Engine.h)
  Aggregates EntityManager, ComponentManager, and a lot of Systems. Calls methods of Systems via next order (see table). Init - methods are called once, when entity is just linked to System, but isn't immidiately, entity is pushed to init-queue and initiated on next frame. Destroy - methods are called once, when entity is just unlinked to System, but isn't immidiately, entity is pushed to destroy-queue and destroyed on next frame.

Systems methods ordrers
Engine init :
SomeEngineSystem::init(EngineLogic::SystemsOrders::Init::ORDER_0)
SomeEngineSystem::init(EngineLogic::SystemsOrders::Init::ORDER_N...)
SomeEngineSystem::init(EngineLogic::SystemsOrders::Init::ORDER_0, const ECS::EntityIdType)
SomeEngineSystem::init(EngineLogic::SystemsOrders::Init::ORDER_N..., const ECS::EntityIdType)
User init :
SomeUserSystem::init(UserLogic::SystemsOrders::Init::ORDER_0)
SomeUserSystem::init(UserLogic::SystemsOrders::Init::ORDER_N...)
SomeUserSystem::init(UserLogic::SystemsOrders::Init::ORDER_0, const ECS::EntityIdType)
SomeUserSystem::init(UserLogic::SystemsOrders::Init::ORDER_N..., const ECS::EntityIdType)
System update :
SomeEngineSystem::update(EngineLogic::SystemsOrders::update::ORDER_0)
SomeEngineSystem::update(EngineLogic::SystemsOrders::update::ORDER_N...)
SomeEngineSystem::update(EngineLogic::SystemsOrders::update::ORDER_0, const ECS::EntityIdType)
SomeEngineSystem::update(EngineLogic::SystemsOrders::update::ORDER_N..., const ECS::EntityIdType)
User update :
SomeUserSystem::update(UserLogic::SystemsOrders::update::ORDER_0)
SomeUserSystem::update(UserLogic::SystemsOrders::update::ORDER_N...)
SomeUserSystem::update(UserLogic::SystemsOrders::update::ORDER_0, const ECS::EntityIdType)
SomeUserSystem::update(UserLogic::SystemsOrders::update::ORDER_N..., const ECS::EntityIdType)
User postUpdate :
SomeUserSystem::postUpdate(UserLogic::SystemsOrders::postUpdate::ORDER_0)
SomeUserSystem::postUpdate(UserLogic::SystemsOrders::postUpdate::ORDER_N...)
SomeUserSystem::postUpdate(UserLogic::SystemsOrders::postUpdate::ORDER_0, const ECS::EntityIdType)
SomeUserSystem::postUpdate(UserLogic::SystemsOrders::postUpdate::ORDER_N..., const ECS::EntityIdType)
System postUpdate :
SomeEngineSystem::postUpdate(EngineLogic::SystemsOrders::postUpdate::ORDER_0)
SomeEngineSystem::postUpdate(EngineLogic::SystemsOrders::postUpdate::ORDER_N...)
SomeEngineSystem::postUpdate(EngineLogic::SystemsOrders::postUpdate::ORDER_0, const ECS::EntityIdType)
SomeEngineSystem::postUpdate(EngineLogic::SystemsOrders::postUpdate::ORDER_N..., const ECS::EntityIdType)
User destroy :
SomeUserSystem::destroy(UserLogic::SystemsOrders::destroy::ORDER_0)
SomeUserSystem::destroy(UserLogic::SystemsOrders::destroy::ORDER_N...)
SomeUserSystem::destroy(UserLogic::SystemsOrders::destroy::ORDER_0, const ECS::EntityIdType)
SomeUserSystem::destroy(UserLogic::SystemsOrders::destroy::ORDER_N..., const ECS::EntityIdType)
System destroy :
SomeEngineSystem::destroy(EngineLogic::SystemsOrders::destroy::ORDER_0)
SomeEngineSystem::destroy(EngineLogic::SystemsOrders::destroy::ORDER_N...)
SomeEngineSystem::destroy(EngineLogic::SystemsOrders::destroy::ORDER_0, const ECS::EntityIdType)
SomeEngineSystem::destroy(EngineLogic::SystemsOrders::destroy::ORDER_N..., const ECS::EntityIdType)

• Each method order must be registered in EngineSystemsOrders.h or UserSystemsOrders.h
• Each component must be registered in EngineComponents.h or UserComponents.h
• Each system must be registered in EngineSystems.h or UserSystems.h