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@nikki93
Created June 2, 2021 04:41
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//
// Entities
//
using Entity = entt::entity;
inline constexpr auto nullEntity = entt::null;
// The global entity registry
inline entt::registry registry;
// Create a new entity
Entity createEntity() {
return registry.create();
}
// Destroy an entity
inline std::vector<void (*)(Entity)> componentRemovers;
void destroyEntity(Entity ent) {
for (auto &remover : componentRemovers) {
remover(ent);
}
registry.destroy(ent);
}
// Destroy all entities
void clearEntities() {
registry.each(destroyEntity);
}
//
// Components
//
// Component pools
template<typename T>
void remove(Entity ent);
template<typename T>
inline auto componentPool = []() {
componentRemovers.emplace_back(remove<T>);
return entt::storage<T>();
}();
// Check whether entity has a component
template<typename T>
bool has(Entity ent) {
return componentPool<T>.contains(ent);
}
// Get a component on an entity
template<typename T>
decltype(auto) get(Entity ent) {
return componentPool<T>.get(ent);
}
// Add a component to an entity
template<typename T>
decltype(auto) add(Entity ent) {
if (has<T>(ent)) {
return get<T>(ent);
} else {
return componentPool<T>.emplace(ent);
}
}
// Remove a component from an entity
template<typename T>
void remove(Entity ent) {
if (has<T>(ent)) {
if constexpr (requires { remove(ent, *((T *)nullptr)); }) {
remove(ent, get<T>(ent));
}
componentPool<T>.remove(ent);
}
}
// Query component combinations
template<typename T, typename... Ts, typename F>
void each(F &&f) {
for (auto ent : static_cast<entt::sparse_set &>(componentPool<T>)) {
if ((has<Ts>(ent) && ...)) {
f(ent, get<T>(ent), get<Ts>(ent)...);
}
}
}
// Sort component data
template<typename T, typename F>
void sort(F &&f) {
componentPool<T>.sort(std::forward<F>(f));
}
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