# File lib/bio/graphics/glyph.rb, line 525
  def self.gradients #needs to know which of its gradients are predefined
    [:red_white_h, :green_white_h, :blue_white_h, :yellow_white_h, :red_white_radial, :green_white_radial, :blue_white_radial, :yellow_white_radial ]
  end