constrain darktable draw mask to right angles and straight lines

I saw this somewhere, but cannot find it or figure it out, but I want to draw a mask that follows straight lines and right angles (or other angles but not curved). There is, I believe, some key that I can press while drawing the mask that will constrain the drawn shapes to straight lines and sharply defined corners.

Can anyone help?



For the path, hold cntrl while adding nodes. To change an existing node cntrl+click on it.

Thank you for the reply,and it was certainly easy enough. However, as I finish the path, there always occurs what I consider a “wild” section of the path between the first node and the last, a sort of curve or curl that occurs. If image conditions allow, I locate this section off the canvas where it has no effect on the image. In some situations, this is not possible.
Any additional suggestions?

Thanks for the reply!


No idea about that.

I have the same problem. I can sometimes get a tidy end. If you right-click, to end the selection, on the same point as you left-click (or crtl-left-click) this will give tidy endpoint. Otherwise I will edit the points, creating the curl, afterwards and delete as necessary.