How to draw a perpendicular line from a point?

I want to draw a line perpendicular from a point… but when I select that option, the perpendicular choice gets forgotten…

GIF 2021-09-22 12-33-01

I bet it’s something basic I’m missing, but what?

It is perpendicular from the line, not the surface - therefore it can be anywhere on a 360 degree circle with the line as its axis.

Sorry, should have said, to get a line perpendicular to a surface you need the Normal option, not the Perpendicular. Subselect the surface rather than selecting the object too.

Note that there appears to be a bug with this: if you select a corner point of your surface (of say a box) then you get a line in the plane of the surface, not normal to it (@pascal).

Thanks, I see that now!

Let me explain from a user experience standpoint what confused me: Because the line projection in the viewport is 2D, there was basically nothing telling me that the perpendicular option was still active…


Since there’s a white line indicating the perpendicularity initially, it would help a lot if there would be a circle indication for the result after you’ve selected from a point as well.

EDIT: Another UI inconsistency… with Line Normal you select the surface first and draw the line second, with Fin you select the line first and the surface second… :roll_eyes:

Hi Jeremy - I see this, thanks.
RH-65719 Line:Normal finds the wrong face in a polysurface


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Yep, got that, it bugs we as well.
RH-65720 Line: perpendicular feedback

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RH-65719 is fixed in Rhino 7 Service Release 12 Release Candidate