Key combination to draw lines on multiples of 15 degrees (15°/30°/45°/60°/75°/90°...)

[anonymous]

Could you add a key combination or modifier (Alt + Shift?) to the Draw nodes (A) tool that allows you draw only new segments that are X degrees apart from the previous segment, where X is a multiple of 15?

This would allow the creation of geometrically precise areas in an easy way. Such functionality is available on all the vector graphics applications: Inkscape, Blender, Gimp (in its vector parts), ecc.

[simon04]

A similar feature is implemented in the plugin buildings_tools (cf. AngleSnap).

[akks]

Here is the patch I made. Please have a look at it when you have time.
Patch is looking rather messy because of moving large fragments of code to different lines.

The code of DrawAction is huge and very complex. I tried not to affect its general behaviour, only extracted some code fragments into separate function.

SnapHelper is the new inner class which manages angle snapping.

Angle Snapping is activated by pressing TAB button while in drawing mode currently.