PIGGE
|-- Driver                OS- and API-specific driver modules
|   |-- Archive.pm        Archive handler base class
|   |-- Base.pm           Driver module base class
|   |-- FS.pm             Archive and search path aware file system 
|   |-- SDLOpenGL.pm      SDL and OpenGL driver
|   |-- TimeHiRes.pm      Time::HiRes driver
|   |-- WAD.pm            WAD archive driver
|   `-- YAML.pm           YAML file driver
|
|-- Library               Extension libraries for particular ports/demos
|   |-- BPGLLines.pm      Library for bp-gllines port
|   |-- ChalsallBlackHole.pm   Library for chalsall-blackhole port
|   |-- ChalsallCube.pm   Library for chalsall-cube port
|   `-- PIGGEDemo.pm      Library for PIGGE feature demo
|
|-- Math                  Math-related modules
|   `-- Rotation.pm       Spatial rotations expressed in various forms
|
|-- Callgraph.pm          Source filter that converts a callgraph into Perl
|-- Commands.pm           Standard command set and utility functions
|-- Config.pm             Default PIGGE configuration
|-- Convert.pm            Conversion functions
|-- Light.pm              Class representing a light source
|-- Main.pm               The main module that applications should inherit from
|-- MainBase.pm           Main's base class -- an overall engine callgraph
|-- Particles.pm          Class representing a particle system
|-- Physics.pm            Physics functions
|-- Player.pm             Class representing a player
|-- Random.pm             Random functions
|-- Shapes.pm             Class representing builtin shapes (deprecated)
|-- SourceFilter.pm       Standard sugary source filter used by most modules
`-- WorldObject.pm        Base class for all world objects