skybox management

[joevenzon]

General info on what a skybox or skydome is:
http://en.wikipedia.org/wiki/Skybox_(video_games)

VDrift organizes all of the rendered geometry using a scenegraph:
http://en.wikipedia.org/wiki/Scenegraph

Each node in the scenegraph can have multiple DRAWABLE objects. Each DRAWABLE object represents a render-able piece of geometry. When a track is loaded the parameters of each drawable object are set up based on the track's objects/list.txt file. Here's a description of the list.txt file's format:
http://wiki.vdrift.net/Track_files_and_f...2Flist.txt

One of the parameters define whether or not the object is a skybox. When VDrift does the final rendering of the scenegraph, it draws skyboxes slightly differently than normal objects (no lighting, no depth buffer writing, and no camera translation). Search in graphics.cpp for skybox and you'll see exactly how it's used.