anchor.diff:  
   == "Adding" Rotations
   
  -You can concatenate (add) rotations: This means you turn the object first around one axis, then around the other, in one step.
  +You can concatenate (add) rotations: This means you turn the object first around one axis, then around the other, in one step. +
  +`Quaternion myRotation =  pitch90.mult(roll45); /* pitch and roll */`
   
  -`Quaternion myRotation =  pitch90.mult(roll45); /* pitch and roll */`
   
   
   == Troubleshooting Rotations
  
positive.code: .  Did you enter the angle in degrees (0 - 360°) or radians (0 - 2*PI)? A 3D engine expects radians, so make sure to convert your values! Formula: `g° = FastMath.PI * g / 180`
  
  
  == Tip: Transformation Matrix
  
  This here is just about rotation, but there are three types of 3-D transformation: <<jme3/rotate#,rotate>>, <<jme3/scale#,scale>>, and <<jme3/translate#,translate>>.
  
  You can do all transformations in individual steps (and then update the objects geometry and bounds), or you can combine them and transform the object in one step. If you have a lot of repetitive movement going on in your game it's worth learning more about Transformation Matrices for optimization. JME can also help you interpolate the steps between two fixed transformations.
  
  +
  
  *  com.jme3.math.Transform, interpolateTransforms() – interpolate a step between two transformations
  **  link:http://javadoc.jmonkeyengine.org/com/jme3/math/Transform.html[com.jme.math.Transform]
  
negative.code: ifdef::env-github,env-browser[:outfilesuffix: .adoc]
  
  
  _Bad news: 3D rotation is done using matrix calculus. +
  Good news: If you do not understand calculus, there are two simple rules how you get it right._
  
  
  *3D rotation* is a crazy mathematical operation where you need to multiply all vertices in your object by four floating point numbers; the multiplication is referred to as concatenation, the array of four numbers {x,y,z,w} is referred to as quaternion. Don't worry, the 3D engine does the tough work for you. All you need to know is:
  
  *The Quaternion* is an object capable of deep-freezing and storing a rotation that you can apply to a 3D object.
  
  
  
  == Using Quaternions for Rotation
  