Are there any ways to manipulate the stage canvas manually? I've wanted to try doing things such as integrating 3D and 2D graphics libraries, videos, and other stuff like drawing an SVG in realtime, and I was wondering if there was any way you can access and manipulate the stage canvas like most other web canvases? (In a way that wouldn't accidentally draw on top of Snap! itself or the IDE)
The stage isn't a canvas. There's only one canvas, the entire Snap! window. So, the quick answer is no. This may change when Jens finishes rewriting Morphic; I'm not sure. Meanwhile, what I'd do is read the code for the map library, which adds a layer between the background and the pen trails, and do the same thing it does, whatever that is. :~)