Sketch in a flat plane

Hi, I am trying to figure out if it is possible in Rhino to sketch on a completely flat plane in an orthogonal view. I have noticed that even though it looks like the sketch is on a plane, when I go back into perspective I see the sketch has snapped to points further back in the model. Is there a way to project to a sketch plane to ensure that the sketch remains flat?..


Well by default when you sketch (by clicking on the canvas) everything will be drawn on your construction plane of choice which is planar. When you have neither object snaps nor smart track enabled new curves or points you create should always lie on the construction plane.
If you want this behaviour disable object snaps and smart track, also have a look at the “_Cplane” command

Yes, that makes sense. The issue is that I need to snap to the existing geometry as a reference to create my new sketch. It seems so simple to just want to project everything to a plane so it’s all flat, and then start creating a new sketch based on what is already there. Maybe I’m just used to software that can do this…

Project to Cplane does not project all the objects which is quite frustrating.


I think you are looking for ProjectOsnap command.

Yes, that definitely helps, thankyou. Is there still no way to project all of the geometry outlines to the construction plane though?

Some objects do project while others do not… Could be a lot more powerful and a great deal more of a useful script if done correctly, I feel.

you mean something like SetPt?

Can you please explain it more, What kind of objects are you dealing with? What command are you using?

If you are working with meshes or any other kind of tridimensional objects that doesn’t work with project to cplane, you could also use _make2d command and generate a flat drawing of your 3D referenced object.
But if you share an example with us, we might be able to better help you.

My God, YES! that command is exactly what I need. That is perfect. It projects everything to the chosen cplane just as you’d expect. Fantastic.

Mahdiyar - Setpt is good for the image projection, but does allow you to snap to every outline that using make2D does.

Thanks so much guys, I owe you!.


I’m glad it worked out for you!

Hi Michael - ProjectToCPlane (Transform menu) is probably the simplest way.


Hi Pascal, ‘ProjectToCplane’ was the first thing I tried. In fact it is the tool I would expect to do the job but sadly it does not actually project all the profile outlines of the shapes being projected, nor does it project polysurfaces at all - not very useful.

On the other hand, make2D does project EVERY object, including polysurfaces via snappable outlines to a cplane - very useful. It just has an awkward name that you would not expect to look for to do the job.


ProjectToCPlane projects polysurfaces for me, creating a polysurface on the CPlane.
Make2D creates a silhouette curve on the CPlane.

@michael8 Do you know about Planar? Rhinoceros Help

Hi David - it will fail if the faces are compressed to nothing - say you project a box on the direction of its vertical sides.