Feature: snapping to guide angle

[Johan Forsberg]

(I'm sorry if this functionality is already present, but in that case I can't find it...)

It would be useful to create a couple of nodes with particular angles and then be able to snap drawing tools to these *directions* but not their positions; like the way the line tool behaves when you press ctrl, only it "snaps" to the angles of any defined guides instead of predefined steps of 15 degrees. This would provide a sort of "poor man's perspective tool" for isometric type drawings, among other things. Of course a grid could be used but sometimes a grid is too restricting.

I suppose Shift+Ctrl or some other key combination could be used for aligning line segments to guides.

What would be *really* cool is if the segments snapped in this way would stick to the guides and change if you rotated the guides... but I think it may be practically impossible.

[Alexandre Prokoudine (alexandre-prokoudine)]

Upcoming 0.47 version has paraxial mode for Pen tool that does exactly what you want :)

[Maximilian Albert (cilix)]

Alexandre: I'm not sure if that's exactly what he means. Johan, could you provide a simple picture illustrating your idea?

[Johan Forsberg (johan-slentrian)]

Wow, quick reply!

I've attached a sketch of how I think it would work. If this is already doable, you guys are awesome :)

I noticed that the node tool does not actually do "angle snapping" which I guess is reasonable as it might have to snap two line segments at the same time when editing a path. I suppose that may also be a problem in this case, so maybe "node" in the attached image should be replaced by "pencil" or "pen". But if it's possile to snap line segments to angles while editing nodes, that would be really neat.

[Maximilian Albert (cilix)]

One thing which you can already do is to convert a line to a guide (press Shift+G or use Object->Object to Guides while the line segment is selected). Then you can edit the node and it will snap to the guide (provided snapping is turned on). If you want to remove the guide, switch to Selector tool by pressing Space, Ctrl+click on it, and press Space again to switch back. Does this help you with your workflow?

But I agree that nodes should also be constrained to the direction of the adjacent line segment (not only horizontally or vertically) when pressing Ctrl. If I understand correctly, your suggestion is even more comprehensive, but would this suffice as an improvement for your purposes? What I don't understand from the drawing is how you want to tell Inkscape that the node should follow a specific guide but not other ones if they are present.

[Johan Forsberg (johan-slentrian)]

Yes I accidentally discovered this function (convert a line to a guide) while making the attached image. It is very helpful for some cases, but if you want to draw something like the example in my image it's not so useful I think.

In my imaginary feature, the node would snap so that the line(s) connected to it would align with the guide closest to it/them in angle (not spatially). Just like Ctrl+pen tool for instance, which snaps to angles in 15 degree intervals. If you have several guides, it would simply choose the one with an angle closest to the angle you're pointing at. I can see however how that may be a problem when editing a node in a path, where two lines are affected by the movement of one path... I guess it would have to have a tolerance for alignment in that case.

Your idea about keeping the angle with Ctrl is very good, but it's not quite what I'm after since it will only help if the line is already at the correct angle.

[Johan Forsberg (johan-slentrian)]

Correction: above, in teh sentence "where two lines are affected by the movement of one path..." I wrote "path" but meant of course "node".