Question

This may be the wrong approach, but as I dig deeper into developing my game engine I have ran into a timing issue.

So lets say I have a set of statements like:

for(int i = 0; i < 400; i++)
{
     engine->get2DObject("bullet")->Move(1, 0);
}

The bullet will move, however, on the screen there won’t be any animation. It will basically “warp” from one part of the screen to the next.

So, I am thinking…create a vector of function pointers for each base object (which the user inherits from) and when they call “Move” I actually don’t move the object until the next iteration of the game loop.
So something like:

while(game.running())
{
     game.go();
}

go()
{
     for(...)
          2dobjs.at(i)->action.pop_back();
}

Or something like that, and this way it runs only a single action of each object during each iteration (of course I’ll add in a check to see if there is actually “actions” to be ran).

And if that is a good idea, my question is how do I store the parameters. Since each object can do more than a single type of “action” rather than move (rotateby is one example), I think it would be nonsensical to create a struct similar in fashion to:

struct MoveAction {
     MovePTR...;
     int para1;
     int para2;
};

Thoughts? Or is this the completely wrong direction?

Answer 1

I don’t think this is the right direction. After you store 400 moves in a vector of function pointers, you’ll still need to pop and perform a move, redraw the screen, and repeat. Isn’t it easier just to move(), redraw, and repeat?

I’d say your bullet is warping because it’s moving 400 pixels/frame, not because you need to delay the move calculations.

But if this is the correct solution for your architecture, in C++ you should use classes rather than function pointers. For example:

class Action // an abstract interface for Actions
{
public:
    virtual void execute() = 0; // pure virtual function
}

class MoveAction: public Action
{
public:
    MoveAction(Point vel) : velocity(vel) {}
    virtual void execute();
    Point velocity;
    ...
}

std::vector<Action*> todo;

gameloop
{
    ...
    todo.push_back(new MoveAction(Point(1,0))
    ...
}