Fri, 09/12/2025 - 18:22
I have a valid BSpline nurbs surface, which I can make into a face with no trimming and will be properly displayed. I also have a wire which I can use successfully to trim the surface to a face which is the complement (inversion) of the face I want to produce:
outer_wire = topods.Wire(outer_wire); outer_wire.Orientation(TopAbs_FORWARD)
mkf = BRepBuilderAPI_MakeFace(base_support, outer_wire, False)
You can see the trim to the complement of what I want in the images, BSPLINE_Surf is before any trimming, then with the code above I get sections of that surface that are exactly opposite (complement/ inverted) to what I want. When I flip the orientation to TopAbs_REVERSED, I get the same resulting face, up to some small aritfacts around the 2d surface resulting from the cut.
What am I missing? I cannot figure out how to cut into BSpline surfaces correctly and can only get them to be correct for cases where there are no trimming wires. Does anyone have a good code example of this? I think it might be made more difficult because the trimming wires lie on the boundary of the BSpline surface for about half of their length??
Please disregard the other surfaces, they are simply other surfaces from the model I am working with and are handeled well.
What I have tried:
messing with the orientation and True/False in BRepBuilderAPI_MakeFace
using shape fix orientation on the resultant face and messing with orientation and True/False in BRepBuilderAPI_MakeFace
How I make the wire:
Create edges by projecting their points from 3d (poles for a bspline edge in the wire) onto the bspline surface UV, then making an edge using the 2d bspline surface and the edge in UV "mk_edge = BRepBuilderAPI_MakeEdge(line2d, base_support)"
then I run shape fix wire
fixer = ShapeFix_Wire()
fixer.SetPrecision(precision)
fixer.Load(outer_wire)
fixer.SetFace(BRepBuilderAPI_MakeFace(base_support, 1e-9).Face())
fixer.Perform()
fixer.FixReorder()
fixer.FixConnected()
fixer.FixClosed()
outer_wire = fixer.Wire()
Thank you for the help!
