Change the command handler to update its own list of entities

examples/snake/src/main.cpp

@@ -302,7 +302,7 @@ int main(int argc, char *argv[]) {
     auto snake_food = std::make_shared<SnakeFoodEntity>(window_size, snake_player);
     game.AddEvent(new simpleengine::EntityEvent(game.GetWindow(), snake_food));
     game.AddEvent(new simpleengine::EntityEvent(game.GetWindow(), snake_player));
-    game.AddEvent(new simpleengine::CollisionHandler(game.GetWindow(), { snake_player, snake_food } ));
+    game.AddEvent(new simpleengine::CollisionHandler(game));
 
     return game.Run();
 }

include/simpleengine/events/collision_handler.h

@@ -11,16 +11,20 @@
 #include "../entity.h"
 
 namespace simpleengine {
+    class Game;
     class CollisionHandler : public Event {
     public:
-        explicit CollisionHandler(sf::RenderWindow* window, std::vector<std::shared_ptr<Entity>> entities) : simpleengine::Event(window), entities(entities) {
+        explicit CollisionHandler(simpleengine::Game& game) : simpleengine::Event(nullptr), game(game) {
 
         }
 
         void Update(const float& delta_time) override;
         void Render(sf::RenderTarget* target) override { }
+
+        void UpdateHandledEntities();
     private:
-        std::vector<std::shared_ptr<Entity>> entities;
+        std::vector<std::shared_ptr<Entity>> handled_entities;
+        simpleengine::Game& game;
     };
 }
 

include/simpleengine/game.h

@@ -16,12 +16,15 @@
 #include <functional>
 
 #include "entity.h"
+#include "events/collision_handler.h"
 
 namespace simpleengine {
     class Event;
 
     class Game {
     public:
+        friend class CollisionHandler;
+        
         Game(int w, int h, const std::string& window_name);
         Game(const sf::Vector2u& window_size, const std::string& window_name);
         virtual ~Game();

src/events/collision_handler.cpp

@@ -6,13 +6,34 @@
 
 #include "events/collision_handler.h"
 #include "components/collision_component.h"
+#include "entity.h"
+#include "events/entity_event.h"
+#include "game.h"
+
+#include <algorithm>
 
 void simpleengine::CollisionHandler::Update(const float& delta_time) {
-    for (std::shared_ptr<Entity> entity : entities) {
+    // Update list of handled entities.
+    handled_entities.erase(std::remove_if(handled_entities.begin(), handled_entities.end(),
+        [](std::shared_ptr<simpleengine::Entity> ptr) { return ptr == nullptr; }), handled_entities.end());
+
+    for (simpleengine::Event* event : game.events) {
+        auto* entity_event = dynamic_cast<simpleengine::EntityEvent*>(event);
+        
+        if (entity_event) {
+            std::shared_ptr<simpleengine::Entity> entity = entity_event->GetEntity();
+            if (std::count(handled_entities.begin(), handled_entities.end(), entity) == 0) {
+                handled_entities.push_back(entity);
+            }
+        }
+    }
+
+    // Check for collisions in all entities.
+    for (std::shared_ptr<Entity> entity : handled_entities) {
         std::shared_ptr<CollisionComponent> entity_col = entity->GetComponent<simpleengine::CollisionComponent>();
 
         if (entity_col) {
-            for (std::shared_ptr<Entity> two : entities) {
+            for (std::shared_ptr<Entity> two : handled_entities) {
                 if (two == entity) continue;
 
                 std::shared_ptr<CollisionComponent> two_col = two->GetComponent<simpleengine::CollisionComponent>();