text: //
  //  UtilityJoint.h
  //  
  //
  
  #import "UtilityMesh.h"
  
  @interface UtilityJoint : NSObject
  
  @property (weak, nonatomic, readonly) UtilityJoint * 
     parent;
  @property (strong, nonatomic, readonly) NSArray * 
     children;
  @property (assign, nonatomic, readonly) GLKVector3 
     displacement;  // Displacement from parent bone
  @property (assign, nonatomic, readwrite) GLKMatrix4 
     matrix;        // local matrix
  
  - (id)initWithDisplacement:(GLKVector3)aDisplacement
     parent:(UtilityJoint *)aParent;
     
  - (GLKMatrix4)cumulativeTransforms;
  - (GLKVector3)cumulativeDisplacement;
  
  @end
  