Problem Split Patch Surface

[vincent1976]

Step by step screenshot.

1. Create Box
   

   

2. Split Box from Curve
   

   

3. Result Split
   

   

4. Create Patch (Default Settings)
   

   

5. Result create patch
   

   

6. Untrim Patch
   

   

7. Result Untrim Patch
   

   

8. Split Patch (Split Crv)
   

   

9. Result Split Patch
   

   

Why split result very bad?

[martinsiegrist]

The split curves seem to be circular. Did you create them with a sphere on the corner? In that case why don’t you just boolean difference the two objects?

[wim (Wim Dekeyser)]

Hi Vincent -

@vincent1976

Why split result very bad?

When you try to split the patch with the cube-object, you will notice that it fails. That is because the edges of the cube are not within tolerance of the patch surface. When you then force a split with those edges, they have to somehow be pulled to the patch surface, and, in this case, that produces a trim curve that is rather unlike the input.

The better way to deal with this is to untrim the surfaces of the cube and use those surfaces that cleanly intersect the patch surface to trim the patch.
-wim