[solved]Non-solids (surface) boolean operations?

[xianyu]

hi,
I have a surface, generated by the following code (too many point data to list).

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import Part
point = [ FreeCAD.Vector(0,0,0), FreeCAD.Vector(1,0,0), ......]  # example
intSurf = Part.BSplineSurface()
intSurf.interpolate(point)
Part.show(intSurf.toShape())

I want to turn the surface into a solid.(similar to the first shape)
(The surface in the picture is generated from a sphere, a simple example)

03.png (14.58 KiB) Viewed 937 times

I think of two ways
1. By boolean operation? (I tried it, non-solids cannot boolean operations)
2. Use "Part.makeShell" and "Part.makeSolid", but I don't know how to get the arc of the surface to "Part.makeShell".(I only know how to use point to make)

Any help or suggestion is welcome,Thanks in advance

Code: Select all

OS: Windows 10 Version 2009
Word size of FreeCAD: 64-bit
Version: 0.20.29177 (Git)
Build type: Release
Branch: releases/FreeCAD-0-20
Hash: 68e337670e227889217652ddac593c93b5e8dc94
Python 3.8.10, Qt 5.15.2, Coin 4.0.1, Vtk 8.2.0, OCC 7.6.2

[chrisb]

What should a boolean do in the case of your Cube and Shape? The only sensible thing I can imagine right now is to cut the cube from the shape and that works well.

[xianyu]

What should a boolean do in the case of your Cube and Shape? The only sensible thing I can imagine right now is to cut the cube from the shape and that works well.

You mean when they coincide, use "Part.Cut"? No matter if I use cube or surface cut, they disappear or give an error

04.png (10.22 KiB) Viewed 896 times

[chrisb]

You mean when they coincide, use "Part.Cut"? No matter if I use cube or surface cut, they disappear or give an error
04.png

If they coincide and I cut the cube from the shape, there is nothing left. Cutting a surface from something doesn't make sense, because it has no volume and thus doesn't take anything away.
I had looked at this:

SnipScreenshot-2a2e91.png (15.35 KiB) Viewed 875 times

If I cut the cube, the remainder is this:

SnipScreenshot-ca64e8.png (6.72 KiB) Viewed 875 times

[xianyu]

If I cut the cube, the remainder is this:

Yes, the cuts are valid, but, I want to compose a solid, similar to the first shape, have any idea?

02.png (8.13 KiB) Viewed 864 times

[chrisb]

You have to create the other surfaces too, combine them into one shape and make solid from that shape. If the height of the dome was determined by the cube, then you could use Slice apart.

[onekk]

Yes, the cuts are valid, but, I want to compose a solid, similar to the first shape, have any idea?
02.png

This will not be achieved by simply transform the surface you provided, as you could even extrude (probably Pad in PartDesign WB), but it will not make the shape as in the figure.


Probably this code will do something similar.

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"""Sample code.

This code was written as an sample code

Author: Carlo Dormeletti
Copyright: 2022
Licence: CC BY-NC-ND 4.0 IT
"""

import math

import FreeCAD
from FreeCAD import Placement, Rotation, Vector
import Part


def setview():
    """Rearrange View."""
    FreeCAD.Gui.SendMsgToActiveView("ViewFit")
    FreeCAD.Gui.activeDocument().activeView().viewAxometric()

DOC_NAME = "calk"

if FreeCAD.ActiveDocument is not None:
    if FreeCAD.ActiveDocument.Name== DOC_NAME:
        FreeCAD.closeDocument(DOC_NAME)

DOC = FreeCAD.newDocument(DOC_NAME)

sh_dim = 8
sh_len = 15

sp_rad = math.sqrt(pow(sh_dim, 2) * 2.0) / 2.0

sph1 = Part.makeSphere(sp_rad)
#Part.show(sph1, "sphere")

box = Part.makeBox(sh_dim, sh_dim, sh_len)
box.Placement = Placement(Vector(sh_dim * -0.5, sh_dim * -0.5, 0), Rotation(0,0,0))
# Part.show(box, "box")

solid = box.fuse(sph1)

f1 = 1.1
f2 = 1.2

cb_dim = sp_rad * f1 * 2

cb_len = (sh_len + sp_rad)

box1 = Part.makeBox(cb_dim, cb_dim, cb_len * f1)
box2 = Part.makeBox(sh_dim, sh_dim, cb_len * f2)
box2.Placement = Placement(Vector((cb_dim - sh_dim) * 0.5, (cb_dim - sh_dim) * 0.5, cb_len * (f2 - f1) * -0.5), Rotation(0,0,0))

# Part.show(box1, "box1")
# Part.show(box2, "box2")

cut_obj = box1.cut(box2)
cut_obj.Placement = Placement(Vector(cb_dim * -0.5, cb_dim * -0.5, sp_rad * -1), Rotation(0,0,0))
#Part.show(cut_obj, "cut_obj")

end_solid = solid.cut(cut_obj).removeSplitter()
Part.show(end_solid, "end_solid")

setview()

I have tried to do something paramtetric.

20220919-calk.png (15.6 KiB) Viewed 781 times

EDIT:

It is difficult to be more generic as the surface is difficult to "inspect" you could extrude it and obtain something similar, but you have to find the boudbox to make a proper cut solid to obtain the face.


Tested on:

Code: Select all

OS: Artix Linux (openbox)
Word size of FreeCAD: 64-bit
Version: 0.20.1.29410 (Git) AppImage
Build type: Release
Branch: (HEAD detached at 0.20.1)
Hash: f5d13554ecc7a456fb6e970568ae5c74ba727563
Python 3.10.5, Qt 5.15.4, Coin 4.0.0, Vtk 9.1.0, OCC 7.6.2
Locale: Italian/Italy (it_IT)
Installed mods: 
  * Curves 0.5.7

Hope it helps

Regards

[onekk]

Maybe this thread could give you some ideas:

https://forum.freecadweb.org/viewtopic.php?f=3&t=30893

Not very clear, but maybe a starting point:

https://forum.freecadweb.org/viewtopic.php?f=3&t=60464

https://forum.freecadweb.org/viewtopic. ... im+surface

Hope it helps

Regards

Carlo D.

[xianyu]

Many thanks @chrisb @onekk
I saw something similar from thread, I think I need a little time to try it

edit: using Part WB SliceApart