Animation - Learning C# by Programming Games - page 343

Now that the preparatory work is done, we assign the current animation to the sprite
member variable:
sprite = animations[id];
Finally, we also change the origin of the animated game object. If we want to draw
animated characters moving on the floor, then it would be much more useful to use
a point on the bottom of the character sprite as its origin. Also, as we will see later
on, this is useful for collision checking. For these reasons, we are going to define
the origin of the animated game object as the point in the middle of the bottom of
the sprite element:
origin = new Vector2(sprite.Width / 2, sprite.Height);
Finally, the Update method of the AnimatedGameObject class calls the Update
method on the currently selected animation. For the complete AnimatedGameObject
class, see Listing 26.1 .
26.6 The Player Class
In order to use the AnimatedGameObject class introduced in the previous section, we
inherit from it. Since the player will control the animated character, let us define a
Player class that is a subclass of the AnimatedGameObject class. Within this class, we
load the animations belonging to the player, and handle the input from the player.
The full Player class is shown in Listing 26.2 . In the constructor of the Player class,
we load the animations that are needed for this character. In this example, we want
the character to walk or stand still. So, we load two animations and add them to the
dictionary by calling the LoadAnimation method. We want both of these animations
to loop, so we set the looping parameter to true :
this .LoadAnimation("Sprites/Player/spr_idle", "idle", true );
this .LoadAnimation("Sprites/Player/spr_run@13", "run", true );
Now we need to handle the input of the player in this class. When the player presses
the left or right arrow key, the velocity of the character should change. We do this
in the HandleInput method using an if -instruction (see Listing 26.2 ).
In the Update method, we select which animation to play based on the veloc-
ity. If the velocity is zero, we play the idle animation, otherwise we play the 'run'
animation:
if (velocity.X == 0)
this .PlayAnimation("idle");
else
this .PlayAnimation("run");