I have a polyline in Rhino where the starting point is at Z=0 and the end point is at Z=20. If I offset manually to the inside in Rhino and use the InCPlane=No then it looks great:
If I run rs.OffsetCurve to programmatically offset the curve it comes out just like the “non-clean” version. How to I get rs.OffsetCurve to give me the other version? There is no “InCPlane” option. I imagine the Offset command in Rhino with the InCPlane=No option does not use the current CPlane so maybe it uses the object’s CPlane. Am I right? Maybe I need to pass the normal to rs.OffsetCurve, but there’s not a CPlane for the object when I select it with rs.GetObject.
the rs.OffsetCurve method has an optional input normal which you could use to feed in the normal of the curve’s plane. To get this plane, you would do this:
plane = rs.CurvePlane(crv_id, -1)
normal = plane.ZAxis
However, i would recommend to use some RhinoCommon where you can offset in a plane without having to declare a point for the offset direction. The direction is relative to the curve’s plane, so i entered 10 as the distance. To offset on the other side, you would use a negative number:
import Rhino
import scriptcontext
import rhinoscriptsyntax as rs
def TestOffset():
crv_id = rs.GetObject("", rs.filter.curve)
if not crv_id: return
curve = rs.coercecurve(crv_id, -1, True)
tolerance = scriptcontext.doc.ModelAbsoluteTolerance
is_planar, plane = curve.TryGetPlane(tolerance)
if not is_planar: return
style = Rhino.Geometry.CurveOffsetCornerStyle.Sharp
rc = curve.Offset(plane, 10, tolerance, style)
if not rc: return
for crv in rc: scriptcontext.doc.Objects.AddCurve(crv)
scriptcontext.doc.Views.Redraw()
TestOffset()
Just a side observation: a planar object offset outside of its own plane becomes non-planar so, strictly, this is a clean representation of that non planar object.
(Provided you have selected Corner=Sharp: if you select Corner=None then I wouldn’t expect the corner ends to be joined but they are. I think this is wrong, @pascal, albeit trivial.)
