Animation - Learning C# by Programming Games - page 342

In order to store the different animations, we will use a Dictionary object. This
way, we can easily select another animation by looking through the dictionary and
choosing the appropriate animation based on an ID. The dictionary is declared as a
member variable in the AnimatedGameObject class.
protected Dictionary< string ,Animation> animations;
We also add two methods to the class: LoadAnimation and PlayAnimation . The first
method creates an Animation object and adds it to the dictionary:
Animation anim = new Animation(assetname, looping, frametime);
animations[id] = anim;
The AnimatedGameObject class is a subclass of SpriteGameObject . That means that
when this object is drawn on the screen, it will try to draw the sprite sheet that the
member variable sprite points to. However, note that the AnimatedGameObject class
has the following constructor:
public AnimatedGameObject( int layer = 0, string id = "")
: base ("", layer, id)
{
animations = new Dictionary< string , Animation>();
}
Because we pass along the empty string to the base constructor, the sprite variable
will contain the value null . What we need to do is assign the currently running an-
imation to the sprite member variable, so that this animation is then drawn on the
screen. We can easily do this, since the Animation class is a subclass of SpriteSheet ,
which is also the type of the sprite member variable. We do this in the PlayAnimation
method.
In that method, we first check if the animation we want to play is already playing.
If that is the case, we do not have to do anything else and we can return from the
method:
if (sprite == animations[id])
return ;
Next, we check if we should copy the current mirror information, so that the newly
assigned animation will have the same mirrored state:
if (sprite != null )
animations[id].Mirror = sprite.Mirror;
Then, we call the Play method on the animation, so that the animation is initialized
and reset to the first frame:
animations[id].Play();