Possible bug with Sketches and Boolean Fragments

[jtm2020hyo]

Boolean fragments tool should split each Sketcher Edge in the intersections, but this just fails with Edge16, no idea why and I think this is very sure a bug.



this happens in 0.19 and 0.20

Code: Select all

OS: Windows 10 (10.0)
Word size of FreeCAD: 64-bit
Version: 0.20.24847 (Git)
Build type: Release
Branch: master
Hash: 20e756306d9aa624fcbf465f0345d721673ce720
Python version: 3.9.2
Qt version: 5.12.9
Coin version: 4.0.0
OCC version: 7.5.1
Locale: Spanish/Peru (es_PE)

[chrisb]

I think this is very sure a bug.

I don't agree. Boolean Fragments works on several shapes, not a single one.

[Roy_043]

But apparently the edges in the sketch are seen as separate objects by the command. All edges are cut at the intersections, all except one.

[chrisb]

If something undocumented works in many, but not all cases, doesn't make it a bug for the cases where it doesn't work.

Besides: may I ask for the use case of such boolean fragments?

[openBrain]

Boolean fragments tool should split each Sketcher Edge in the intersections, but this just fails with Edge16, no idea why and I think this is very sure a bug.

Actually you're 2 times wrong.

1) Not only Edge16 isn't cut, but also Edge27

bf.png (5.94 KiB) Viewed 2554 times

2) All this is perfectly normal and absolutely not a bug
According wiki :

Generally, at least two objects are needed, but a single compound containing the shapes to intersect will do as well.

Below a picture where I extracted and colored the subshapes contained in the sketch Compound shape, and you can see that what you get perfectly matches the fragments obtained by intersecting all different subshapes against each other.

bfshapes.jpeg (20.02 KiB) Viewed 2554 times

[UR_]

You can simply explode sketch with DowngradeToEdges using Lattice2 WB and apply BooleanFragments afterwards.

Screenshot 001.png (4.12 KiB) Viewed 2536 times

Sketch_Lattice2Downgrade_BooleanFragments.FCStd

(18.8 KiB) Downloaded 73 times

[jtm2020hyo]

1) Not only Edge16 isn't cut, but also Edge27

bf.png

delete some lines fix this for Edge27



... maybe is there any limit? if not, then I still think this is a bug.

_______________________________________________________________________

You can simply explode sketch with DowngradeToEdges using Lattice2 WB and apply BooleanFragments afterwards.

Screenshot 001.png

maybe this work but we lost the parametric feature, I found 2 alternatives to this problem

1) Split manually each Intersection

2) Separate Horizontal and Vertical Lines in 2 Sketches then Apply boolean again.

... in both cases we still have parametric features, but is an extra task

Besides: may I ask for the use case of such boolean fragments?

Code: Select all

https://forum.freecadweb.org/viewtopic.php?f=3&t=58731

with nested Faces Edges and Vertex, we can create an entire pre-project just with 3 Sketches, in theory.

[UR_]

...maybe this work but we lost the parametric feature...

With Downgrade from Lattice2 WB, parametric is preserved, in opposite to Downgrade from Draft WB.

[openBrain]

... maybe is there any limit? if not, then I still think this is a bug.

No limit, no bug. It works strictly as designed and as documented.
Eventually it just doesn't fit your needs.

[jtm2020hyo]

Code: Select all

https://wiki.freecadweb.org/Part_Slice

according to Part_Slice documentation, Boolean Fragments should splitter intersections





... also @UR_ user showed us that Boolean Fragments works correctly with Lattice2 WB Edges

...then why Boolean Fragments work with Lattice2-WB and not with Sketcher-WB?