CurveBoolean CombineRegions=Yes, AllRegions - programmatically?

Scripting
1

As you see in the video, for a bunch of curves, if I select an outer point I get combined regions combining all curves closed or open.

How do I do this programatically ?
RhinoCommon does not expose CurveBoolean’s region-picking as one call.
I also cannot specify a Point3D for the outside point.

2

Hi @Bogdan_Chipara,

Can you post your curves?

– Dale

3

Thanks @dale for looking into this.
You have a file with several curves.
Note that units are in mm and absolute tolerance is set to 1 unit.
On most of these groups the curve boolean works well from Rhino.
260115 Curve boolean from API.3dm (4.5 MB)

4

Have a look here:

5

@AndersDeleuran ,

Curve.CreateBooleanRegions is a bad strategy because:

  • All regions must have a point (from the documentation)
  • I have too many curves, it will run into trouble when trying to boolean all of them.
  • Self-intersections of curves produce failures.

What CurveBoolean does in Rhino with CombineRegions=Yes, AllRegions=Yes and a single point specified outside the desired region is something different and in my opinion it is not exposed in RhinoCommon or rhinoscriptsyntax.

6

I didn’t see your original case in the Rhino file (and might not be fully understanding the issue), but here’s a quick go with the first three cases from your Rhino file:

2026-01-16 16_59_34-C__Users_andersh_Downloads_260115 Curve boolean from API.3dm (4 MB) - Rhino 8 Co
2026-01-16 16_59_34-C__Users_andersh_Downloads_260115 Curve boolean from API.3dm (4 MB) - Rhino 8 Co3278×1207 171 KB

Note that you have some floaters down here:

2026-01-16 17_02_56-C__Users_andersh_Downloads_260115 Curve boolean from API.3dm (4 MB) - Rhino 8 Co
2026-01-16 17_02_56-C__Users_andersh_Downloads_260115 Curve boolean from API.3dm (4 MB) - Rhino 8 Co2495×933 54.2 KB

240712_CreateBooleanRegions_00.gh (122.0 KB)

7

Thanks! It works as expected.

#CurveBooleanRegions
import Rhino
import scriptcontext as sc
import rhinoscriptsyntax as rs

def create_boolean_region_curves():
    # Select curves
    go = Rhino.Input.Custom.GetObject()
    go.SetCommandPrompt("Select intersecting curves")
    go.GeometryFilter = Rhino.DocObjects.ObjectType.Curve
    go.SubObjectSelect = False
    go.GroupSelect = True
    go.GetMultiple(2, 0)
    if go.CommandResult() != Rhino.Commands.Result.Success:
        return

    crvs = []
    for i in range(go.ObjectCount):
        c = go.Object(i).Curve()
        if c: crvs.append(c.DuplicateCurve())

    if not crvs:
        return

    # Determine plane (try from first planar curve, else WorldXY)
    plane = Rhino.Geometry.Plane.WorldXY
    ok, pln = crvs[0].TryGetPlane()
    if ok:
        plane = pln

    # Options
    tol = sc.doc.ModelAbsoluteTolerance
    combine = True

    # Compute boolean regions
    regs = Rhino.Geometry.Curve.CreateBooleanRegions(crvs, plane, combine, tol)
    if not regs or regs.RegionCount == 0:
        print("No regions found (check curve intersections / planarity / tolerance).")
        return

    # Add resulting region boundary curves to document
    new_ids = []
    for i in range(regs.RegionCount):
        region_crvs = regs.RegionCurves(i)  # boundary curves for this region
        for rc in region_crvs:
            if rc:
                new_ids.append(sc.doc.Objects.AddCurve(rc))

    sc.doc.Views.Redraw()
    print("Created {} region boundary curves (from {} regions).".format(len(new_ids), regs.RegionCount))

if __name__ == "__main__":
    create_boolean_region_curves()
8

This really got me confused.

  • points
  • Type: IEnumerable
  • These points will be projected to plane. All regions that contain at least one of these points will be found