// particles, but it could be used by a SoundSystem to play an explosion
// sound, etc..
class CollisionSystem : public ex::System<CollisionSystem> {
+ static const int PARTITIONS = 200;
+
+ struct Candidate {
+ sf::Vector2f position;
+ float radius;
+ ex::Entity entity;
+ };
+
public:
+ explicit CollisionSystem(sf::RenderTarget &target) : size(target.getSize()) {
+ size.x = size.x / PARTITIONS + 1;
+ size.y = size.y / PARTITIONS + 1;
+ }
+
void update(ex::EntityManager &es, ex::EventManager &events, double dt) override {
- Body::Handle left_body;
- Collideable::Handle left_collideable;
- for (ex::Entity left_entity : es.entities_with_components(left_body, left_collideable)) {
+ reset();
+ collect(es);
+ collide(events);
+ };
+
+private:
+ std::vector<std::vector<Candidate>> grid;
+ sf::Vector2u size;
- for (ex::Entity right_entity : es.entities_with_components<Body, Collideable>()) {
- if (left_entity == right_entity) continue;
+ void reset() {
+ grid.clear();
+ grid.resize(size.x * size.y);
+ }
+
+ void collect(ex::EntityManager &entities) {
+ Body::Handle body;
+ Collideable::Handle collideable;
+ for (ex::Entity entity : entities.entities_with_components(body, collideable)) {
+ unsigned int
+ left = static_cast<int>(body->position.x - collideable->radius) / PARTITIONS,
+ top = static_cast<int>(body->position.y - collideable->radius) / PARTITIONS,
+ right = static_cast<int>(body->position.x + collideable->radius) / PARTITIONS,
+ bottom = static_cast<int>(body->position.y + collideable->radius) / PARTITIONS;
+ Candidate candidate {body->position, collideable->radius, entity};
+ unsigned int slots[4] = {
+ left + top * size.x,
+ right + top * size.x,
+ left + bottom * size.x,
+ right + bottom * size.x,
+ };
+ grid[slots[0]].push_back(candidate);
+ if (slots[0] != slots[1]) grid[slots[1]].push_back(candidate);
+ if (slots[1] != slots[2]) grid[slots[2]].push_back(candidate);
+ if (slots[2] != slots[3]) grid[slots[3]].push_back(candidate);
+ }
+ }
- Body::Handle right_body = right_entity.component<Body>();
- Collideable::Handle right_collideable = right_entity.component<Collideable>();
- if (collided(left_body, left_collideable, right_body, right_collideable))
- events.emit<CollisionEvent>(left_entity, right_entity);
+ void collide(ex::EventManager &events) {
+ for (const std::vector<Candidate> &candidates : grid) {
+ for (const Candidate &left : candidates) {
+ for (const Candidate &right : candidates) {
+ if (left.entity == right.entity) continue;
+ if (collided(left, right))
+ events.emit<CollisionEvent>(left.entity, right.entity);
+ }
}
}
- };
+ }
-private:
float length(const sf::Vector2f &v) {
return std::sqrt(v.x * v.x + v.y * v.y);
}
-
- bool collided(Body::Handle r1, Collideable::Handle c1, Body::Handle r2, Collideable::Handle c2) {
- return length(r1->position - r2->position) < c1->radius + c2->radius;
+ bool collided(const Candidate &left, const Candidate &right) {
+ return length(left.position - right.position) < left.radius + right.radius;
}
};
systems.add<BodySystem>();
systems.add<FadeOutSystem>();
systems.add<BounceSystem>(target);
- systems.add<CollisionSystem>();
+ systems.add<CollisionSystem>(target);
systems.add<ExplosionSystem>();
systems.add<RenderSystem>(target, font);
systems.configure();
projects / clyne / entityx.git / commitdiff