Flattensurf.dll handle surface with holes or elipse through?

[PeterDnz]

I've got surfaces with ellipses punched through them. When I use the .dll the holes are filled in on the resulting flat surface. Any way of preserving the hole geometry?

[Colin Gilchrist]

It is a multi-step process, but yes, it can be done. First you need to make sure your spline creation type is set to 'parametric'. If your splines are 'NURBS' splines, you will have to convert them into parametric (create-spline-curves spline). Just rechain them and it will create a new parametric spline.

 

Once you have parametric splines, use Create-Curve-Surface Curve. This will turn the parametric spline into a surface curve. Once you have surface curves, you can use the Map.dll Chook to map the curves from your curves surface to your flat surface. You'll also need to map your trimmed edge curves onto the flattened surface too.

 

Check the curves from the top view and be sure they look right. If they look weird, you probably need to flip the U/V direction.

 

Once the curves have been mapped to the new surface, Use the Cons2spline.dll chook to turn the surface curve into a parametric spline.

 

It's a process for sure, but it can be done.

 

Then you can trim the flattened surface to the new mapped splines...

 

HTH,

[Rob Dusenbury CAD/CAM CONSULTING]

Colin,

 

Great job explaining these steps!!

 

I had a customer last week wanting to do the exact same thing.

 

Here is a little trick that may also help. If you save your file as a VDA, it will convert all of your splines and surfaces to Parametric. Read back in the VDA, and use Colin's steps.

[Colin Gilchrist]

Hey, good tip Rob, thanks.

 

I also set my default spline creation type to Parametric in the Config file, so any file I import usually has only parametric to begin with. There is also a "convert to NURBS" function in the edit menu, so in the few cases where I need to move a spline's endpoint, I convert it to NURBS to do that. I like the VDA trick though, I'll have to try that.

[PeterDnz]

Have trouble at the Map.dll stage. don't get any curves showing on my flattened surface.

[Colin Gilchrist]

Are you sure you have "surface curves" on your parent surface? If all you have is splines, they will not be mapped. Only surface curves are mapped. Map.dll will prompt you to select a surface with surface curves on it, then select the suface to map them to.

 

I've had problems mapping curves if they are right at the edge of a surface. Try "untrimming" your surface, the creating the 'surface curves' from your splines, then mapping.

 

I do this on at least a weekly basis...

[Colin Gilchrist]

One more thing...

 

If these curves on on the inside of the surface, you can use "remove boundary" to untrim just the interior voids in the surface and it will not un-trim the outside...

 

HTH,

[PeterDnz]

Thanks for the help Colin, I'll get some practice.