Basic Skeletal Animation code in Scala

gistfile1.scala

class Skeleton(val name:String) {
  val joints = new ArrayBuffer[Joint]()
  val jointsByName = new HashMap[String, Joint]() // convenience only
  var rootJoint:Option[Joint] = None
}

class Joint {
  var name:String = "unnamed joint :-("

  val relativeTranslation = new Vector3d() // relative to parent
  val absoluteTranslation = new Vector3d() // absolute (relative to model root)

  // I use orientations so I can bring skeleton's created/posed in different styles on to 
  // a common set of orientations (hands by sides), so I can apply one animation to various skeletons.
  val relativeOrientation = new Quaternion4d()
  var absoluteOrientation = new Quaternion4d()

  var children = new ArrayBuffer[Joint](0)
}

class PosedSkeleton(val skeleton:Skeleton) {
  val posedJoints = new ArrayBuffer[PosedJoint]()
  val posedJointsByName = new HashMap[String, PosedJoint]() // again, convenience only

  var rootPosedJoint:Option[PosedJoint] = None

  var rootTranslation = new Vector3d() // I use this for offsetting the skeleton from the models' normal position

  def computeTransformationMatrices() {
    computeTransformationMatrixForJoint(rootPosedJoint.get, Matrix4d.Identity)
  }

  def computeTransformationMatrixForJoint(posedJoint:PosedJoint, baseTransform: Mat4d) {
    val inverseTranslate = Matrix4d.translate(posedJoint.joint.absoluteTranslation * -1)
    val orientation = Matrix4d.rotationFor(posedJoint.joint.relativeOrientation))
    val rotation = Matrix4d.rotationFor(posedJoint.relativeRotation)
    val translate = Matrix4d.translate(posedJoint.joint.absoluteTranslation)

    posedJoint.transform = inverseTranslate * rotation * orientation * translate * baseTransform

    posedJoint.children.foreach(pj => computeTransformationMatrixForJoint(pj, posedJoint.transform))
  }
}

class PosedJoint(val joint:Joint) {
	var relativeRotation = new Quaternion4d()

  val children = new ArrayBuffer[PosedJoint]()

  var transform = new Matrix4d() // used as a cache for the posed joint's full transform matrix (useful for rendering)
}