Creating the Animation Data Classes in Font

Creation PDF417 in Font Creating the Animation Data Classes

You ll create the classes used to store the skeletal animation data in a separate library, so that they can be used by the animated model processor to store the skeletal animation data and by the game application to load this data at runtime. Begin by creating a new Windows Game Library project named AnimationModelContentWin. The model processor will use the classes in this library on the Windows platform to store the skeletal animation data. If your game is targeted to the Windows platform, this library will also be used to load the skeletal animation data in runtime.

If you re targeting the Xbox 360, you need to create one more project: an Xbox 360 Game Library named AnimationModelContentXbox. This library contains the same files as the AnimationModelContentWin library, but Xbox 360 applications use it to load the skeletal animation at runtime. You need the AnimationModelContentWin project even if you re targeting the Xbox 360 platform, because the original model files are imported and processed on the Windows platform, and this project contains the class definitions. You ll create the following three classes to store the skeletal animation data: The Keyframe class stores an animation frame of a skeletal animation, where each animation frame stores the configuration for a bone in the skeleton. The AnimationData class stores an array of keyframes, which compose a complete animation (such as running, jumping, and so on). The AnimatedModelData class stores the model skeleton (bones and hierarchy) and an array of type AnimationData, containing all the model animations.

The Keyframe class is responsible for storing an animation frame for a bone in the skeleton. An animation frame must have a reference for the animated bone, the new configuration (position and orientation) of the referenced bone, and the time in which this new configuration should be applied. Note that you use the keyframes to modify the original bone configuration, changing its current configuration to a new one. You store the bone configuration as a matrix using XNA s Matrix class, and you store the animation time (the time after which this keyframe should be applied) as a TimeSpan. You store the reference for the bone that will be animated as an integer representing the index of the bone in the bones array of the AnimatedModelData class. The Keyframe class code follows: public class Keyframe : IComparable { int boneIndex; TimeSpan time; Matrix transform; // Properties... public TimeSpan Time { get { return time; } set { time = value; } } public int Bone { get { return boneIndex; } set { boneIndex = value; } }

public Matrix Transform { get { return transform; } set { transform = value; } } public Keyframe(TimeSpan time, int boneIndex, Matrix transform) { this.time = time; this.boneIndex = boneIndex; this.transform = transform; } public int CompareTo(object obj) { Keyframe keyframe = obj as Keyframe; if (obj == null) throw new ArgumentException("Object is not a Keyframe."); return time.CompareTo(keyframe.Time); } } In the Keyframe class, you re implementing the interface IComparable to be able to compare Keyframe objects. You ll use this comparison further to use C# sorting functionality to easily sort the keyframes according to their time frame. In order to implement the IComparer interface, you need to define the CompareTo method. This method accepts an object that needs to be compared to the current object, and returns 1 if this object is larger than the object passed as argument, 1 if this object is smaller than it, or 0 if this object is equal to it. The Keyframe objects are compared based on their time attribute.

The AnimationData class is responsible for storing a complete model animation (such as running, jumping, and so on). You store each animation as a Keyframe array, and along with its keyframes, you store other useful data, such as the animation name and duration. The code for the AnimationData class follows: public class AnimationData { string name; TimeSpan duration; Keyframe[] keyframes; public string Name { get { return name; } set { name = value; } }