On the surface of control point for the question?

Rhino Developer
1

C#, how to obtain the coordinate data of all the control points on the surface of a block? Thank you!

2

I haven’t tested this. But this would work:

public Rhino.Geometry.Point3d[] BlockSurfaceControPointLocations(Rhino.DocObjects.InstanceObject iref)
{
  var points = new List<Rhino.Geometry.Point3d>();
  if (null != iref)
  {
    // transformation applied to an instance definition for this object
    var xform = iref.InstanceXform;
    // instance definition that this object uses
    var idef = iref.InstanceDefinition;
    if (null != idef)
    {
      // Get array with the objects that belong to this instance definition
      var rh_objs = idef.GetObjects();
      foreach (var rh_obj in rh_objs)
      {
        // Try getting surface geometry
        var srf = rh_obj.Geometry as Surface;
        if (null != srf)
        {
          // Convert surface to a NURBS surface
          var ns = srf.ToNurbsSurface();
          if (null != ns)
          {
            // Process each control point
            foreach (var cp in ns.Points)
            {
              // Transform point using instance definition's transform
              var pt = cp.Location;
              pt.Transform(xform);
              points.Add(pt);
            }
          }
        }
      }
    }
  }

  if (points.Count > 0)
    return points.ToArray();

  return null;
}