Question

Basically what I want to do is store the reference to the active animation of a sprite as a private member in the Actor class. I want to use a reference so I don’t have to actually create the animation multiple times but I keep getting an error.

Actor class declaration:

class Actor
{
public:
        Actor();
        ~Actor();
        void setActiveAnimation(Animation anim);
        void draw(sf::RenderWindow& win);

private:
        sf::Sprite sprite;
        MaJR::Animation& activeAnimation;
};

Actor class implementation:

Actor::Actor()
{
    // constructor
}

Actor::~Actor()
{
    // destructor
}

void Actor::setActiveAnimation(Animation anim)
{
    activeAnimation = anim;
    activeAnimation.gotoStart();
}

void Actor::draw(sf::RenderWindow& win)
{
    sprite.setTexture(activeAnimation.getActiveFrame());
    win.draw(sprite);
    activeAnimation.nextFrame();
}

Build output:

/home/mike/MaJR Game Engine/src/Actor.cpp||In constructor 'MaJR::Actor::Actor()':|
/home/mike/MaJR Game Engine/src/Actor.cpp|8|error: uninitialized reference member 'MaJR::Actor::activeAnimation' [-fpermissive]|
||=== Build finished: 1 errors, 0 warnings ===|

Answer 1

A reference cannot be reassigned, so it must be initialized at the member-initialization-list. However, you intend to reassign it so what you want is not a reference. What’s more, in your setActiveAnimation function you are setting such reference to a copy of the value passed as an argument, which leaves you with an invalid reference when the code exits the function. Perhaps a pointer would suit you?

In the class body:

MaJR::Animation* activeAnimation;

And the setActiveAnimation function:

void Actor::setActiveAnimation(Animation* anim)
{
    activeAnimation = anim;
    activeAnimation->gotoStart();
}