The engine is really basic and consists of a main "scene" object (Engine) in which geometry (Geometry objects) can be registered. After registration these objects will be .update()-ed each tick after which they are immediatly drawn. Everything is drawn every tick.
The perspective formula used is: for each (x,y,z) in "object space", the screen coordinates are:
x(screen) = x(object) / z y(screen) = y(object) / z