A `Skeleton`(defined in `scene/skeleton.h`) is what we use to drive our animation. You can think of them like the set of bones we have in our own bodies and joints that connect these bones. For convenience, we have merged the bones and joints into the `Joint` class which holds the orientation of the joint relative to its parent as euler angle in its `pose`, and `extent` representing the direction and length of the bone with respect to its parent `Joint`. Each `Mesh` has an associated `Skeleton` class which holds a rooted tree of `Joint`s, where each `Joint` can have an arbitrary number of children.
All of our joints are ball `Joint`s which have a set of 3 rotations around the <imgsrc="task2_media/0027.png"style="height:14px">, <imgsrc="task2_media/0028.png"style="height: 16px">, and <imgsrc="task2_media/0029.png"style="height: 16px"> axes, called _Euler angles_. Whenever you deal with angles in this way, a fixed order of operations must be enforced, otherwise the same set of angles will not represent the same rotation. In order to get the full rotational transformation matrix, <imgsrc="task2_media/0030.png"style="height:16px">, we can create individual rotation matrices around the <imgsrc="task2_media/0031.png"style="height:16px">, <imgsrc="task2_media/0032.png"style="height:16px">, and <imgsrc="task2_media/0033.png"style="height:16px"> axes, which we call <imgsrc="task2_media/0034.png"style="height:20px">, <imgsrc="task2_media/0035.png"style="height:20px">, and <imgsrc="task2_media/0036.png"style="height:20px"> respectively. The particular order of operations that we adopted for this assignment is that <imgsrc="task2_media/0037.png"style="height:20px">.
All of our joints are ball `Joint`s which have a set of 3 rotations around the <imgsrc="task2_media/0027.png"style="height:14px">, <imgsrc="task2_media/0028.png"style="height: 16px">, and <imgsrc="task2_media/0029.png"style="height: 16px"> axes, called _Euler angles_. Whenever you deal with angles in this way, a fixed order of operations must be enforced, otherwise the same set of angles will not represent the same rotation. In order to get the full rotational transformation matrix, <imgsrc="task2_media/0030.png"style="height:16px">, we can create individual rotation matrices around the <imgsrc="task2_media/0031.png"style="height:16px">, <imgsrc="task2_media/0032.png"style="height:16px">, and <imgsrc="task2_media/0033.png"style="height:16px"> axes, which we call <imgsrc="task2_media/0034.png"style="height:20px">, <imgsrc="task2_media/0035.png"style="height:20px">, and <imgsrc="task2_media/0036.png"style="height:20px"> respectively. The particular order of operations that we adopted for this assignment is that <imgsrc="task2_media/task2_rotations.png"style="height:20px">.