Part.Face.curveOnSurface return wrong result

[tomate44]

Part.Face.curveOnSurface return wrong result

[maxwxyz]

@bgbsww related to TNP?

[bgbsww]

Quick test shows it happening in 0.21.2 where TNP is still off. It also happens in LS3 and in 0.20.2 Is the example code correct, and on what version exactly did it return None?

[tomate44]

Indeed, I observe the same behavior on 0.21.2, and on Appimage 0.20.2 with OCCT 7.6.3
That look strange because I use this function for years, and I am sure it worked fine in the past.
So I have no clue what's going on ???
By the way, here is another script showing the bug :

cone = Part.makeCone(2, 4, 10)
seam = cone.Edge2
Part.show(seam, "Seam")
# This edge has 2 pcurves
print(seam.curveOnSurface(0))
print(seam.curveOnSurface(1))
print(seam.curveOnSurface(3))  # None = no more pcurves

topface = cone.Face2
Part.show(topface, "TopFace")

cos = topface.curveOnSurface(seam)
print(cos)
# should be None because seam has no pcurve on the top face
# instead, the returned curve2D is a projection of the seam on the topface
edge = cos[0].toShape(topface.Surface, cos[1], cos[2])
Part.show(edge, "PCurve")

[tomate44]

I checked into Opencascade source code.
When Face is a plane and no existing pcurve is found, curveOnSurface() does a projection on the plane.
Quite strange it does not check if Edge and Face are coplanar beforehand.
Anyway, I was obviously wrong.
Apologies for the wasted time. I close.