What is Reddit's opinion of G3D Innovation Engine?

From 3.5 billion Reddit comments

Thanks! We used G3D (http://g3d.sourceforge.net) to render and build the scene. Everything was based on a stack based grammar which involved pushing primitives we built in Blender out from cube faces. The city was laid out using Voroni Diagrams.

For having the origin at bottom-left, the one that immediately springs to mind for me is Cocoa. All of the other APIs I've thought to look at (GDI, X11) have used upper-left as origin, so I could be wrong about this being common.

For having a rectangle that is created with xyxy, the framework I use most often (G3D) has factory methods to create Rect2Ds from xyxy, which I find often mesh with how I think about a particular rectangle (e.g., selection rectangles have one point as the first click location, and the second point as the current mouse position)