Snapping to a Section's Clipped Boundary in a Detail View

Is there a way to do it? It may work if line work behind the section is orthagonal to the section to osnap to, but I have a section through mouldings wrapping around a curved wall, and need to dimension the mouldings visible in clipped section, but I can’t snap to anything but the lines through which the section does not go.

Hi David,

Snapping only works on unclipped geometry. The section lines are just a display feature (they do no really exists in the model), so snap feature cannot detect them.

We’re trying to figure a way to solve this.



Any news about this problem? I’m still having the same issue here.

Best Regards,


It is a problem. The purpose of most sections is to dimension the sectioned surfaces.

But it may go beyond Va, because we can’t snap to Clipping Plane cut surfaces either. My workaround - for a non-orthagonally sectioned persepective - is to generate a 2d VaSectionView and layer a Detail with the 2D VaSectionView on top of the Detail with the 3D Hidden view. With a rendered detail also at the bottom of all that, it’s cumbersome.

Another workaround, I guess, is to intersect the geometry with a plane and create an intersection curve at that location. You should then be able to snap to that curve.

Thanks Wim. Wish I’d thought of that.

I see that Pascal offers a ClippingPLaneCurves Rhino script.

Will it work - and be stable - in a Visual Arq Section?

Hi David,

Unfortunately, this script will not work with VisualARQ sections, as this script only looks for Rhino Clipping Plane objects.



Snapping to sections would be much welcome! As would snapping to the level lines in an elevation.

2 options:

  • It’s clear that ‘display’ lines can’t be snap targets so maybe VA object generate ‘real’ section curves instead of just a ‘display’ version?
  • Or, the Rhino snapping gets extended to snap to a special type of geometry that only serves that purpose and isn’t part of the scene. That would be outside of the scope of VA devs of course.

Hi @Eugen,

I agree that the ability to snap to section curves would be awesome. Regarding your options:

  1. It may work with VisualARQ objects, but it won’t for Rhino geometry like poly-surfaces. So this is not a complete solution. Moreover it will make sections slower, as computing real sections curves for certain objects can take some CPU time.
  2. As you have pointed out, this needs some work from McNeel.

I’ll try to take a look and see if we can do something in VisualARQ for the next release.




It works within a Va Section though, as a workaround:
Here it is providing contour lines through a Rhino Object and two VaWalls:
(The Clip Plane is precisely coplanar with the VaSection. ClipPLaneCurves created undesired points and lines as if the VaSection were an object, but it also creates desirable snappable lines at the section cut contours.)

The contour linese are coplanar with the VaSection but they show up in a Detail View with the section cut, and create snappable lines on otherwise non-snappable geometry. For now it’ll have to do.: