Wish: History updating polysurface

What would be really cool is if after you create a SubD surface from a nurbs object that the nurbs object would update as you work on the SubD surface.

Hi Paul -

In your title, you use the word “polysurface”. You can’t (or not really) create a SubD object from a polysurface.

Apart from that, could you describe what problem that updating the ToNURBS version of the SubD object would solve?

Hi Wim

You can see the changes in real time without converting back to nurbs.


that’s not quite how this all works… unless I’m confused about what you are proposing…

1st- SubD is created from a mesh object not a nurbs object-
2nd if you create a nurbs object from a SubD object, it’s a 1-1 conversion so there is no difference.

can you post some screenshots for clarity about your proposal?

I thought that when I make an object in Rhino that it is a nurbs object and then when I use the command ‘convert to subD’ that I was taking a nurbs object and converting it to a subD object. So if I do not delete the input i have a nurbs object and a subD object. Therefore history could work on both objects at the same time.

SubD objects are created from meshes, not NURBS objects. But the command ToSubD allows NURBS surfaces and extrusions as meshes. Here is how both of those statements can be true. If a surface or extrusion is selected as the input object then Rhino creates a mesh of SubD control points from the NURBS object. The choice of UseSurface=Location or UseSurface=ControlPoints determines how that mesh is created.

History in Rhino works in one direction only. Changes to the input of a command cause the output to be updated (for History enabled commands if History was enabled when the command was executed). . Changing the output of command breaks History, it does not change the input object.

For example create a surface from two curves using the Loft command with History enabled. Move one of the input curves and the surface will update to match the moved curve. Move the surface and a message will appear saying that history was broken.