//Base class for any graphics, such as instances, tiles, backgrounds, etc.class CGraphic {public: //I don't really like the "private" scope, yet I don't know why... bool visible; long depth; //If you know how to draw with depth :) virtual bool Draw(); //Any other members/methods related to drawing};//This is the base class of an instance, derrived from a graphicclass CInstance : public CGraphic {public: //Basic data for an object in your game... long id; //My index in the current room's object list ??? object_id; //My type? (for checking collision with certain objects and such... I use my own structure for this) float x, y, hspeed, vspeed; //Position, Movement (yes, it's based off of Game Maker) CSprite *sprite_pointer; //Pointer to my sprite for drawing? long image_index; //Currrent frame of my sprite? CMask *mask_pointer; //Pointer to my mask for collision? //And more... //Methods: //Constructors? virtual bool Create(), Step(), Destroy(); //Create - When created, Step - Each step (frame), Destroy - I think you get it bool Draw(); //Already virtual in CGraphic};//NOTE: For instances, make a create function and a destroy function. With the create function, it is inserted in the list, its Step method is executed, and the user specifies position also. For the destroy function, the instance is removed from the list, and then slaughtered horrifical--er, its Destroy method is executed.//An example class:class CBob : public CInstance { bool Create(), Step(), Draw()};bool CBob::Create() { sprite_pointer=&sprBob; }bool CBob::Step() { //Move Bob according to his movement variables x+=hspeed; y+=vspeed;}bool CBob::Draw() { //Draw Bob's sprite with his sprite pointer, frame, and position}//Room class...class CRoom { //Other information for the room, such as views //Dynamic list for the instances in the room vector<CInstance*> object; vector<bool> object_exists; //Vectors for tiles, backgrounds, etc? bool Step(); //Execute the Step method for each instance bool Draw(); //Draw all of the graphics in this room (instances, tiles, backgrounds)};//A basic function for CRoom::Step() [pseudocode!]bool CRoom::Step() { For each instance in "object"  If the object exists   object[current]->Step(); //Polymorphism will execute the object's unique Step function only Next iteration}bool CRoom::Draw() { Compile graphics into a list ("vector<CGraphic*> my_graphic;" Sort graphics by depth (if you know how to :) [again]) For Each Graphic  If the current graphic is visible   my_graphic[current]->Draw(); Next iteration}

CRoom *room; //This is the pointer which points to the current room, and this is declared somewhere out there in my code.//This is the base function for inserting a instance in a room's list. //NOTE: This function recycles, therefore is a little slower than simply appending a new itemlong instance_register(CInstance *srcInst) { long index=-1; for (long i=0;i<room->object.size();i++) {  if (room->object_exists==false) {   index=i;   break; }  if (room->object==srcInst) return false; //Already registered } if (index==-1) { //An empty space was not found  //Add a new pointer and exists boolean  room->object.push_back(0);  room->object_exists.push_back(false);  index=room->object.size()-1; //The last index } if (room->object[index]!=0) delete room->object[index]; //Remove previous instance memory if not already room->object[index]=srcInst; room->object_exists[index]=true; room->object[index]->id=index; return index;}//Base function which removes an instance's link to a list, but doesn't delete itbool instance_unregister(long id) { //Add your own error handling here! I would add something that checks if the id is bounded inside the list and that the object is actually registered //Remember to set the 'object' equal to 0! room->object[id]=0; room->object_exists[id]=false; return true;}//The more 'refined' functions://This creates registers the instance first, then sets it position and executes its Create method.long instance_create(instance *myInstance,float x,float y) { long index=instance_register(myInstance); if (index==-1) return -1; //Prevent this from making any changes!  myInstance->x=x;  myInstance->y=y;  myInstance->Create(); return index;}//This actually deletes the instance before it is unregistered (you might want to switch the order)bool instance_destroy(long id) { if (room->object_exists[id]==false || room->object[id]==0) return false; room->object[id]->Destroy(); //Execute Destroy method delete room->object[id]; instance_unregister(id); return false;}