What’s the best approach to creating a line perpendicular to a surface normal so that it runs on the surface?

Is there a specific orientation on that surface for the line? Is the surface planar?

Hi Mike - there is an infinite number of possible lines that meet this requirement… needs another constraint.

-Pascal

The surface is planar. I want to show a line on the surface that has the same slope as the surface itself. I have been able to calculate the slope of the surface from the surface normal. I would like to draw a line from the top point down the surface that has the same slope as the surface.

I hope this gives a better context.

Hi Mike - I think the plane you are after can be found by:

the normal line start, the normal line end, either one of these projected to the Cplane or what ever plane the slope is measured against.

Those three points define a plane - intersect with the planar surface to get, I think, the line you want.

-Pascal

Thanks Pascal. I run with that.