Here's a few snap modes that could be useful:
1. Snap to parallel
If there are one or several angled guides around, any straight line you're drawing will snap to a direction parallel to the direction of those guides. It's like drawing paraxial lines, except not just constrained to horizontal and vertical lines. Useful if you need to draw a lot of diagonal lines for example.
(by snapping, it means it will snap when the angle you're drawing approaches that angle. You won't be constrained to just drawing towards those directions)
2. Snap to orthogonal
Same principle as the above, except in a direction orthogonal to existing guides.
3. Snap to node alignment
When you're drawing an object with straight lines, any new point will snap to align to existing points of that line. I'm asking this because creating open-ended rectangles and more complicated straight-line shapes (examples: folder-like shape, thick U shape etc.) are a pain.
Right now I have to either: - create several rectangles - align - combine - open up any extra segments Or: create nearly as many guides for snapping as the number of lines I want to draw (and then I have to delete them) Or: do a so-so job, open up the align dialogue and tediously align each group of nodes
In fact, this snapping is the default behaviour I wish I'd have for paraxial drawing mode, but a snap mode should make a decent compromise for everyone.
4. Snap to guide point direction
This one requires a guide point object first. When you're drawing a straight line, the line will snap in the direction of that point. Useful for perspective drawing, especially if the vanishing points are very far off from the drawing area.