Can't edit subd vertices using python

Scripting
,
#1

Hi,

I am attempting to modify the coordinates of a subd vertex using python. I thought that editing the vertex ControlNetPoint would work (docs say it has both a setter and getter), but the subd does not change. Am I doing something wrong? Code posted below.

Also, it would great to be able to edit the vertex surface point directly rather than the control point. I see that vert.SurfacePoint() returns a Point3d object, but not sure if this is editable or not. Is it possible to edit the surface point directly?

import Rhino

def edit_subd_verts():
    filter = Rhino.DocObjects.ObjectType.SubD
    rc, objref = Rhino.Input.RhinoGet.GetOneObject("Select SubD", False, filter)
    if not objref or rc != Rhino.Commands.Result.Success: return
    
    subd = objref.SubD()
    if not subd: return
        
    vert = subd.Vertices.First
    print(vert.ControlNetPoint)
    vert.ControlNetPoint.X = 30.0 # This has no effect
    
edit_subd_verts()

I am currently using Rhino 7 SR12 2021-11-9 on Windows 10.

Cheers,
Michael

subD control Points in Grasshopper
#2

I think this is not possible, but you can work with Grips or work with the control mesh instead, move the vertices, convert to subd and delete the old subd.

#3

vert.ControlNetPoint.X = 30.0 gets the value of the control point location (copies it to a temporary Point3d) and sets the X property of that value to 30. For this to work like you want, SubDVertex.ControlNetPoint would need to be able to deal with a reference to the control point; I don’t think we have a safe way to do that.

Instead you can set the vert.ControlNetPoint property to a new Point3d:

import Rhino

def edit_subd_verts():
    filter = Rhino.DocObjects.ObjectType.SubD
    rc, objref = Rhino.Input.RhinoGet.GetOneObject("Select SubD", False, filter)
    if not objref or rc != Rhino.Commands.Result.Success: return
    
    subd = objref.SubD()
    if not subd: return
        
    vert = subd.Vertices.First
    print(vert.ControlNetPoint)
    cnp = vert.ControlNetPoint
    cnp.X = 30
    vert.ControlNetPoint = cnp
    print(vert.ControlNetPoint)
    Rhino.RhinoDoc.ActiveDoc.Objects.AddSubD(subd)

Setting surface point locations hasn’t made its way to RhinoCommon yet, it’s being tracked there: RH-59542 Allow for getting and setting SubD “edit” points using RhinoCommon.

1 Like
#4

Thanks Pierre. That does indeed modify the coordinates.

Importantly I was missing Rhino.RhinoDoc.ActiveDoc.Objects.AddSubD(subd) because I thought I could modify the subd inplace without creating a copy.

Looking forward to being able to modify the surface point locations directly.

Cheers,
Michael