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- /*
- * 2D Game Engine
- * ECS.cpp:
- * Based on pikuma.com 2D game engine in C++ and Lua course
- * Copyright (c) 2021 986-Studio. All rights reserved.
- *
- * Created by Manoël Trapier on 11/02/2021.
- */
- #include <Logger.h>
- #include <algorithm>
- #include <ECS.h>
- /* Entity */
- uint32_t IComponent::nextId = 0;
- /* TODO: this should be moved to the header file for optimisation purposes */
- uint32_t Entity::getId() const
- {
- return this->id;
- }
- void Entity::kill()
- {
- this->registry->killEntity(*this);
- }
- /* System */
- void System::addEntity(Entity entity)
- {
- this->entities.push_back(entity);
- }
- void System::removeEntity(Entity entity)
- {
- this->entities.erase(std::remove_if(this->entities.begin(), this->entities.end(), [&entity](Entity other)
- {
- return other.getId() == entity.getId();
- }), this->entities.end());
- }
- std::vector<Entity> System::getSystemEntities() const
- {
- return this->entities;
- }
- const Signature& System::getComponentSignature() const
- {
- return this->componentSignature;
- }
- Entity Registry::createEntity()
- {
- uint32_t entityId;
- if (this->freeIds.empty())
- {
- entityId = this->numEntities++;
- }
- else
- {
- entityId = this->freeIds.front();
- this->freeIds.pop_front();
- }
- Entity entity(entityId);
- entity.registry = this;
- this->entitiesToBeAdded.insert(entity);
- if (entityId >= this->entityComponentSignatures.size())
- {
- this->entityComponentSignatures.resize(entityId + 1);
- }
- Logger::Info("Entity created with id = %d", entityId);
- return entity;
- }
- void Registry::killEntity(Entity entity)
- {
- Logger::Info("Entity #%d flagged for killing", entity.getId());
- this->entitiesToBeKilled.insert(entity);
- }
- void Registry::addEntityToSystems(Entity entity)
- {
- const auto entityId = entity.getId();
- const auto entityComponentSignature = this->entityComponentSignatures[entityId];
- for(auto &system: this->systems)
- {
- const auto systemComponentSignature = system.second->getComponentSignature();
- bool isInterested = (entityComponentSignature & systemComponentSignature) == systemComponentSignature;
- if (isInterested)
- {
- system.second->addEntity(entity);
- }
- }
- }
- void Registry::removeEntityFromSystems(Entity entity)
- {
- for (auto &system: this->systems)
- {
- system.second->removeEntity(entity);
- }
- }
- void Registry::update()
- {
- /* Add pending entities */
- for(auto entity: this->entitiesToBeAdded)
- {
- this->addEntityToSystems(entity);
- }
- this->entitiesToBeAdded.clear();
- for(auto entity: this->entitiesToBeKilled)
- {
- this->removeEntityFromSystems(entity);
- this->entityComponentSignatures[entity.getId()].reset();
- this->freeIds.push_back(entity.getId());
- }
- this->entitiesToBeKilled.clear();
- }
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