Jump to content

Combining Nurbs Surfaces


Recommended Posts

Ok, Created a rectangle and then used the Create Surface From Curves command to make it a nurbs surface. Then I set the U and the V Degrees to 3. I then moved the handles inside the surface using the 3-D Reshape tool to create an undulating plane. The 4 sides of the rectangle are still in the same z coordinate (0), and all of the handles I moved were in the positive z direction.

Now I created another rectangle and again used the Create Curface From Curves command. It is bigger than the first surface, and the first surface is centered in the second. I then traced the first surface with a rectangle and used the Project and trim to to clip the second surface.

Now what I'd like to do is combine the first and second surfaces into a single nurbs surface that can be further modified with the 3-d reshape tool.Is this possible?

Thanks

Link to comment
  • Vectorworks, Inc Employee

You can add the surfaces to create a solid using Add Solids command. But you cannot create a single surface out of the two surfaces as they do not have geometric continuity at the boundary of the first surface where they join. Incidentally, to be more precise you could extract the curves out of the boundaries of the first surface and compose them into a single NURBS curve and use that for trimming.

Link to comment

Yeah, I tried the Add Solids, but you don't get the same ability to edit the geometry as the Nurbs surfaces have. As far as extracting the curves and using them to trim, I'm going to have to think about that one, I'm not sure I understand what your saying.

But I figure I'm going to have to start thinking backwards sometimes to end up where I want to be. smile.gif" border="0

Thanks

Link to comment
  • Vectorworks, Inc Employee

Yes, when you add solids, you don't have the same flexibility. But the 3D Power Pack design is done with this in mind. Wht ayou do in such situations is - convert the Add Solid to NURBS surfaces using Convert To NURBS command and then manipulate these NURBS surfaces and then add them back together if necessary.

Link to comment
  • 12 years later...
... cannot create a single surface out of the two surfaces as they do not have geometric continuity at the boundary of the first surface where they join.

It seems so basic for 3d modeling: why can't a simple command be developed to join 2 NURBs curves into one curve, as can be done with polygons?

  • Like 1
Link to comment
  • 8 years later...

Try this:

 

https://app-help.vectorworks.net/2023/eng/VW2023_Guide/Shapes3/Stitching_and_trimming_surfaces.htm

 

Our friend, Josh, just shared this with me yesterday because a PJ I downloaded from bimobject.com had a NURBS gremlin stowaway along for the ride.

 

Also, that OP is from 2 decades ago but I've used Interpolated NURBS Surfaces which might be more of what you seek. The workflows are a bit like Edge of Tomorrow though: you have to follow the steps to recipe in the right sequence or it will fail, and you have to respawn and start all over again.

 

Link to comment

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...