The common.ulb file

Classes and plug-ins can be useful on their own, but they show their true power when you combine them with each other. When used well, classes can eliminate duplicate code in everyone’s formulas. However, to realize this potential, there needs to be a common foundation so all classes can work with each other easily.

The common.ulb file installed in the Public formula folder provides such a foundation. It contains an extensive collection of base classes, standard plug-ins and utility classes. Here is a quick overview of the most important classes and plug-ins:

  • The Array classes provide a way to pass arrays to functions, since Ultra Fractal doesn’t allow this directly. See also Function arguments.
  • The Generator and IntegerGenerator classes are base classes for plug-ins that generate a sequence of values, such as random number generators.
  • The Transfer and IntegerTransfer classes are base classes for plug-ins that take a value and transform it.
  • The Formula class and descendants such ConvergentFormula, DivergentFormula and ConvergentDivergentFormula wrap a complex fractal formula as a plug-in. See Example 1 – Formula plug-ins for an example of how this works in practice.
  • The Coloring, GradientColoring and DirectColoring classes wrap coloring algorithms as a plug-in.
  • The Transform, UserTransform and ClipShape classes wrap transformations as a plug-in.
  • The TrapShape, TrapMode, TrapColoring, TrapPosition, TrapTransfer and ColorTrap classes provide a plug-in framework to implement orbit trap coloring algorithms where every aspect of the algorithm is extensible. See Example 2 – Orbit trap plug-ins.

The goal is to provide flexible base classes that help formula authors to write plug-ins and formulas that work with existing and future plug-ins and formulas. It is highly recommended to read through the common.ulb file thoroughly before you start writing your own plug-ins. Also have a look at how the standard plug-ins in Standard.ulb are implemented.

The common.ulb file will be continually updated via the online formula database. The UF-programmers mailing list is the best place to discuss this and to suggest modifications.

Documentation for the common.ulb file and any other plug-in library file in the online formula database is accessible via

Next: Memory management

See Also
Importing classes

The common.ulb file