That's an interesting idea, but it's quite specific to add a sound just in
thor::FrameAnimation. If I add such functionality, I will probably implement a separate sound "animation" that can be played parallel to a graphical one.
Don't forget that you can always write your own animations to achieve virtually everything, so you can already now implement such functionality.
struct SoundAnimation
{
void addFrame(float relativeDuration,
const sf::IntRect& subrect, const sf::Sound& sound);
void operator() (sf::Sprite& animated, float progress) const;
};
You can look at the implementation of
thor::FrameAnimation. I'll probably factor out the interval/relative-duration parts, or provide getters, so that one needn't copy-paste the whole code.