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POHandling entities in a game
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copied!<p>As a small exercise I am trying to write a very small, simple game engine that just handles entities (moving, basic AI etc.)</p> <p>As such, I am trying to think about how a game handles the updates for all of the entities, and I am getting a little bit confused (Probably because I am going about it in the wrong way)</p> <p>So I decided to post this question here to show you my current way of thinking about it, and to see if anyone can suggest to me a better way of doing it.</p> <p>Currently, I have a CEngine class which take pointers to other classes that it needs (For example a CWindow class, CEntityManager class etc.)</p> <p>I have a game loop which in pseudo code would go like this (Within the CEngine class)</p> <pre><code>while(isRunning) { Window->clear_screen(); EntityManager->draw(); Window->flip_screen(); // Cap FPS } </code></pre> <p>My CEntityManager class looked like this:</p> <pre><code>enum { PLAYER, ENEMY, ALLY }; class CEntityManager { public: void create_entity(int entityType); // PLAYER, ENEMY, ALLY etc. void delete_entity(int entityID); private: std::vector<CEntity*> entityVector; std::vector<CEntity*> entityVectorIter; }; </code></pre> <p>And my CEntity class looked like this:</p> <pre><code>class CEntity() { public: virtual void draw() = 0; void set_id(int nextEntityID); int get_id(); int get_type(); private: static nextEntityID; int entityID; int entityType; }; </code></pre> <p>After that, I would create classes for example, for an enemy, and give it a sprite sheet, its own functions etc.</p> <p>For example:</p> <pre><code>class CEnemy : public CEntity { public: void draw(); // Implement draw(); void do_ai_stuff(); }; class CPlayer : public CEntity { public: void draw(); // Implement draw(); void handle_input(); }; </code></pre> <p>All of this worked fine for just drawing sprites to the screen.</p> <p>But then I came to the problem of using functions which exist in one entity, but not in another.</p> <p>In the above pseudo code example, do_ai_stuff(); and handle_input();</p> <p>As you can see from my game loop, there is a call to EntityManager->draw(); This just iterated through the entityVector and called the draw(); function for each entity - Which worked fine seeing as all entities have a draw(); function.</p> <p>But then I thought, what if it is a player entity that needs to handle input? How does that work?</p> <p>I haven't tried but I assume that I can't just loop through as I did with the draw() function, because entities like enemies won't have a handle_input() function.</p> <p>I could use an if statement to check the entityType, like so:</p> <pre><code>for(entityVectorIter = entityVector.begin(); entityVectorIter != entityVector.end(); entityVectorIter++) { if((*entityVectorIter)->get_type() == PLAYER) { (*entityVectorIter)->handle_input(); } } </code></pre> <p>But I don't know how people normally go about writing this stuff so I'm not sure of the best way to do it.</p> <p>I wrote a lot here and I didn't ask any concrete questions, so I will clarify what I am looking for here:</p> <ul> <li>Is the way I have laid out/designed my code ok, and is it practical?</li> <li>Is there a better more efficient way for me to update my entities and call functions that other entities may not have?</li> <li>Is using an enum to keep track of an entities type a good way to identify entities?</li> </ul>

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