anchor.diff:  dynamic parameter. Afterglow tries to be as efficient about this as
   possible, and do as much calculation as it can when the parameter is
   created. If there are no frame dynamic parameters, it will return a
  -fixed color. But you can easily use frame-dynamic oscillated parameters
  -and get lovely shifting rainbow cues, as shown in the [[effect
  -examples|effect-examples#oscillator-effects]].
  -
  -[[direction-parameters]]
  -Direction Parameters
  -~~~~~~~~~~~~~~~~~~~~
  +fixed color. But you can easily use frame-dynamic oscillated
  +parameters and get lovely shifting rainbow cues, as shown in the
  +<<effect_functions#oscillator-effects,effect examples>>.
  +
  +== Direction Parameters
   
   Direction parameters are a way to tell a group of fixtures to point in a
   particular direction, or move in unison or in a coordinated pattern. The
  
positive.code: |=======================================================================
  
  All of these parameters, except for `frame-dynamic`, can themselves be
  dynamic parameters, such as show link:#variable-parameters[variables]
  (with the convenience shorthand of just passing in the keyword by which
  the show variable was stored) or link:#oscillated-parameters[oscillated
  parameters].
  
  Refer to [[Working with Color|working-with-color]] for a refresher on
  the meaning of the basic color components. It would not make sense to
  pass all of these parameters, because some will override others, but
  here is how they are evaluated:
  
  1.  The base color is established by the `:color` parameter.
  2.  If any of `:r`, `:g`, or `:b` have been supplied, the color is
  replaced by creating an RGB color with the values (or defaults)
  supplied.
  3.  If any of `:h`, `:s`, or `:l` have been supplied, the color is
  replaced by creating an HSL color with the values (or defaults)
  supplied.
  4.  If `:adjust-hue` was supplied, the hue of the color obtained so far
  is shifted by adding that amount to it (and wrapping around the color
  circle if needed).
  5.  If `adjust-saturation` was supplied, the saturation of the color is
  adjusted by adding that amount to it, maxing out at 100.0, and bottoming
  out at 0.0. Lower saturations yield less colorful (more gray) colors.
  6.  If `adjust-lightness` was supplied, the lightness of the color is
  adjusted by adding that amount to it, maxing out at 100.0, and bottoming
  out at 0.0. A lightness of 50.0 allows for a fully saturated color,
  lightnesses above that start getting whitened, and a lightness of 100.0
  
negative.code: 
  [source,clojure]
  ----
  (afterglow.effects.params/build-variable-param :key)
  ----
  
  