Interpolate points on mesh

Is this possible? I’d like to draw a polyline on a mesh using vertex on osnap but dont get the results I need using the polyline on mesh command (the resulting curve gets ‘sucked down’ onto the vertices between the points chosen). Interpolate curve gives me that smooth line but try as I might I cant see an option in the commands to use a mesh.
Any ideas anyone?

The Vertex Osnap causes a mesh vertex to be selected if the cursor is close enough to a vertex. It sounds like you want to pick points on mesh faces between vertices.

There are two “one shot” Osnaps for picking point locations on mesh faces. OnMesh constrains the cursor to the faces of a selected mesh for the next point selection while executing a command. PersistentOnMesh constrains the cursor to the faces of a selected mesh for point selection until the command is completed.

For interpolating a curve through points on mesh start the InterpCrv command, then immediately type PersistentOnMesh, select the desired mesh, and then select the point locations. This will put a curve with the degree set in the InterpCrv options through the selected points on the mesh faces. However the curve can deviate from the mesh faces between the selected points. Use Pull to pull the curve onto the mesh faces.

For a polyline either InterpCrv with Degree=1 or Polyline can be used.

I am not aware of a method to start the OnMesh or PersistentOnMesh OSnaps without typing.

David you are a genius! That’s exactly what I was looking for, many thanks.