All is said in the title.
Here is a little script that demonstrates the bug.
- pick a face in the 3D view
- copy / paste following script in the python console
- this will show the du and dv derivative vectors of the face, at the picked point
Both vectors should be tangent to the surface at that point.
But, surprisingly, for cones, the dv vector is roughly normal to the surface ???
Code: Select all
s = Gui.Selection.getSelectionEx()[0]
surf = s.SubObjects[0].Surface
pp = s.PickedPoints[0]
u, v = surf.parameter(pp)
pt = surf.getD0(u, v)
du = surf.getDN(u, v, 1, 0)
dv = surf.getDN(u, v, 0, 1)
Part.show(Part.makeLine(pt, pt + du), "du")
Part.show(Part.makeLine(pt, pt + dv), "dv")
Code: Select all
OS: Manjaro Linux (KDE/plasma)
Word size of FreeCAD: 64-bit
Version: 0.20.27770 (Git)
Build type: Release
Branch: master
Hash: 14ff42be1332002fbca7561a203e3104a1fc3a79
Python 3.10.2, Qt 5.15.2, Coin 4.0.1, OCC 7.5.3
Locale: French/France (fr_FR)
Installed mods:
* CurvesWB 0.3.0
* sheetmetal 0.2.49
* workfeature
* pivy_trackers