Curves workbench

[touvenant]

Hello Glouglou, thanks for your answer !

The supportPlane is not at the same position on my draw.
As you can see, mine is bottom turn than yours :

SupportPlane bottom turn.PNG (21.37 KiB) Viewed 1404 times

How did you "attach" the supportPlane on the two curves (yellow and purple) ?
What is "vertex" ?

Thanks

[nic]

Hello to the Gordonists!

I hope I won't spoil the thread... let me know if I should open a new one.


Here is my config:

Code: Select all

OS: Ubuntu 20.04 LTS (Regolith:GNOME-Flashback:GNOME/regolith)
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.19.21300 +2313 (Git) AppImage
Build type: Release
Branch: LinkStage3
Hash: 0f809d2f8f3b8603c0310ffcfb13869710a0ec48
Python version: 3.7.6
Qt version: 5.12.1
Coin version: 4.0.0
OCC version: 7.4.0
Locale: French/France (fr_FR)

See attached model. I don't understand why gordon fails. My rails_XX and Sketch_YY look connected, but Gordon fails with the following error:

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Traceback (most recent call last):
  File "/home/nic/.FreeCAD/Mod/Curves/gordonFP.py", line 135, in execute
    obj.Shape = gordon.surface().toShape()
  File "/home/nic/.FreeCAD/Mod/Curves/gordon.py", line 313, in surface
    self.perform()
  File "/home/nic/.FreeCAD/Mod/Curves/gordon.py", line 287, in perform
    self.gordon_surf = builder.surface_gordon()
  File "/home/nic/.FreeCAD/Mod/Curves/gordon.py", line 100, in surface_gordon
    self.perform()
  File "/home/nic/.FreeCAD/Mod/Curves/gordon.py", line 97, in perform
    self.create_gordon_surface() #self.profiles, self.guides, self.intersectionParamsU, self.intersectionParamsV)
  File "/home/nic/.FreeCAD/Mod/Curves/gordon.py", line 167, in create_gordon_surface
    surfProfiles = bsa.curvesToSurface(self.profiles, self.intersectionParamsV, makeVClosed)
  File "/home/nic/.FreeCAD/Mod/Curves/BSplineAlgorithms.py", line 312, in curvesToSurface
    interpPointsVDir[cpVIdx] = compatSplines[cpVIdx].getPole(cpUIdx+1)
<class 'Part.OCCError'>: Pole index out of range
Recompute failed! Please check report view.

[hammax]

… you have a double set of rails : rails_top-bottom. => Separate them.
Also your frames are not so clear and self explaining - and their distance is "irregular".
Missing frames BB, CC, DD ?
Try the same procedure with the frames in a loft and you'll see the problem.

[nic]

… you have a double set of rails : rails_top-bottom. => Separate them.
Also your frames are not so clear and self explaining - and their distance is "irregular".
Missing frames BB, CC, DD ?
Try the same procedure with the frames in a loft and you'll see the problem.

Thanks Hammax. I thought double sets were allowed! I'll check that. For the frames, their location are known from existing cross sections, which are not equally spaced, unfortunately

[Chris_G]

Hi,

I thought double sets were allowed!

They are.
Mixing rails and profiles inside a single object is forbidden.
But having a single object representing several rails, or several profiles, shouldn't make any problem.
The file doesn't look bad at first sight. I don't know yet where the bug comes from ...

[hammax]

… I tried it again - this time with a weird and oblique "frame AA" result.
I did a lot of gordon hulls till now, but that is a new feature.

Debug_Gordon.PNG (29.61 KiB) Viewed 1251 times

[nic]

Hi,
They are.
Mixing rails and profiles inside a single object is forbidden.
But having a single object representing several rails, or several profiles, shouldn't make any problem.
The file doesn't look bad at first sight. I don't know yet where the bug comes from ...

Thanks to confirm! I managed to solve it by reworking the last two frames sketches (FF and GG). I still don't know what was the problem.

… I tried it again - this time with a weird and oblique "frame AA" result.
I did a lot of gordon hulls till now, but that is a new feature.


Debug_Gordon.PNG

yes, strange. but the loft looks good.

I finally managed to get a precise enough volume by combining Gordon on the AFT part of the sections, and AdditiveLoft for FWD sections

[Vincent B]

I'm trying to build a helix on a pipe. But SketchOnSurface scale the sketch and allow only one turn around the pipe. Could be possible to not scale it? (the lenght of the wire will give the number of revolutions).
Thanks.

[Chris_G]

Do you need a parametric document object ?
Here is a function that creates a simple helix shape :

Code: Select all

def helix_on_face(face, turns=1.0, wire_output=True):
    """
    Create an helix shape on a periodic face.
    helix_shape = helix_on_face(face, turns=1.0, wire_output=True)
    If wire_output is False, helix_shape will be a single edge.
    However, for a high number of turns, OCCT may fail and return some weird result.
    If wire_output is True, helix_shape will be a wire made of single turn edges.
    """
    u0,u1,v0,v1 = face.ParameterRange
    if face.Surface.isUPeriodic():
        ls = Part.Geom2d.Line2dSegment(FreeCAD.Base.Vector2d(u0, v0), FreeCAD.Base.Vector2d(u0 + ((u1-u0) * turns), v1))
    elif face.Surface.isVPeriodic():
        ls = Part.Geom2d.Line2dSegment(FreeCAD.Base.Vector2d(u0, v0), FreeCAD.Base.Vector2d(u1, v0 + ((v1-v0) * turns)))
    else:
        print("Error: Face is not periodic")
        return None
    if not wire_output:
        return ls.toShape(face.Surface)
    pts = ls.discretize(Distance=ls.length()/turns)
    edges = []
    for i in range(len(pts)-1):
        edges.append(Part.Geom2d.Line2dSegment(pts[i], pts[i+1]).toShape(face.Surface))
    return Part.Wire(edges)

[hammax]

Hi GlouGlou,
is your intention something like that?
Done with CurvesWB and attachment.

HelixPipe.PNG (38.5 KiB) Viewed 1105 times