Likewise most 3d graphics software like Maya, Houdini, softimage ICE etc. These types of node-based interfaces tend to arise in applications which need high interactivity and have a fairly specific domain. They usually don't scale well to more general programming. For example, they are great for representing the flow of data through a network of functions but not so great at showing things like loops or recursion. That said, I do think graphics (and music) apps are at the forefront of "visual programming" but they are often not talked about in the context of programming language research. Language designers should be looking to them for inspiration.