anchor.diff:  a| Specify a vector how fast particles move and in which start direction. 
   
   <a| direction           
  -a| `getParticleInfluencer(). setVelocityVariation()` +`setFacingVelocity()` +`setRandomAngle()` +`setFaceNormal()` +`setRotateSpeed()` 
  -a| 0.2f +false +false +Vector3f.NAN +0.0f 
  +a| `getParticleInfluencer(). setVelocityVariation()` +
  +`setFacingVelocity()` +
  +`setRandomAngle()` +
  +`setFaceNormal()` +
  +`setRotateSpeed()` 
  +a| 0.2f +
  +false +
  +false +
  +Vector3f.NAN +0.0f 
   a| Optional accessors that control in which direction particles face while flying. 
   
   <a| lifetime            
  -a| `setLowLife()` +`setHighLife()` 
  -<a| 3f  +7f  
  +a| `setLowLife()` +
  +`setHighLife()` 
  +<a| 3f +
  +7f  
   a| Minimum and maximum time period before particles fade. 
   
   <a| emission rate       
  
positive.code: You have learned that many different effects can be created by changing the parameters and textures of one general emitter object.
  
  Now you move on to another exciting chapter – the simulation of <<jme3/beginner/hello_physics#,physical objects>>. Let's shoot some cannon balls at a brick wall!
  '''
  
negative.code: ----
  
  You create different effects by changing the emitter parameters: 
  [cols="15,45,15,25", options="header"]
  |===
  
  <a| Parameter           
  