Requicha's algorithm in FreeCAD?

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onekk
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Requicha's algorithm in FreeCAD?

Post by onekk »

Following a link about CheckGeometry results, I'm landed in Quaorar forum, among others thing there is this article:

http://quaoar.su/blog/page/on-geometric ... ging-hints

Is this implemented in OCCT and could be used in FreeCAD?

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Carlo D.
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jnxd
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Re: Requicha's algorithm in FreeCAD?

Post by jnxd »

Is there a reason the link is in http? Could you elaborate on where the algorithm is used?
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onekk
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Re: Requicha's algorithm in FreeCAD?

Post by onekk »

jnxd wrote: Tue Mar 21, 2023 8:35 pm Is there a reason the link is in http? Could you elaborate on where the algorithm is used?
Not particular reason, here the point that IMHO seems interesting.
However, the General Fuse algorithm possesses certain deficiencies. Generally speaking, when it works, it's quite alright. But, whenever it stops working, it is a non-trivial question of how would you tune your arguments to fix the problem. This lack of control made us develop a new algorithm based on the analysis of transitions of the contour edges across the boundaries of the input shape. We named it a "Requicha's algorithm" as it is ideologically based on the work of Aristides Requicha,
Quaorar is OCCT developer (maybe former) and has been here on this forum, but now probably due to the well know facts in Eastern Europe, it is not very active.

BTW his blog is very interesting and made with some "inner knowledge" of OCCT.

There is many interesting post filed under "OpenCascade" tag in his blog. @tanderson69 has posted a link in a discussion about "CheckGeometry" and I have simply followed links.

Sorry if it is not related to FreeCAD, but as it is dealing with "problems in a wide used OCCT function" I have thought that it could be interesting to see his argumentations, sadly I'm not so skilled to judge the quality of the approach, but as these times in this forum every people seems to blame OCCT without proposing viable ways to circumvents its flaws, this article seems to be a viable way to find some "quality workaround".

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Carlo D.
GitHub page: https://github.com/onekk/freecad-doc.
- In deep articles on FreeCAD.
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Vincent B
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Re: Requicha's algorithm in FreeCAD?

Post by Vincent B »

Is Analysis Situs could be integrated into freecad one day?
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Re: Requicha's algorithm in FreeCAD?

Post by onekk »

Vincent B wrote: Wed Mar 22, 2023 2:05 pm Is Analysis Situs could be integrated into freecad one day?
I don't know but from the little I could see Analysis Situs is a sort of Playground or Test software for new methods of modelling and probably FEM.

It is more geared toward OCCT as it using TCL and internal OCCT Draw.exe (That probably is the stock way to interface to OCCT).

But as from what I've seen they publish C++ sources for many things so probably someone skilled in C++ could take the code and see if it could be integrated in FreeCAD (if OCCT version could match, as probably being advanced it use latest version of OCCT).

I know that there are many if and could in my post, but it is not a FR it is only a question.

Kind Regards

Carlo D.
GitHub page: https://github.com/onekk/freecad-doc.
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adrianinsaval
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Re: Requicha's algorithm in FreeCAD?

Post by adrianinsaval »

could you link to this analisys situs code? It's not clear where one could find this requicha's algorithm
drmacro
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Re: Requicha's algorithm in FreeCAD?

Post by drmacro »

The mentioned blog starts off discussing something similar to what is shown here, starting at 13:05.
https://youtu.be/3kgyNTTeV6Q

Is it possible Curves is already using the facility in OCCT mentioned in the blog?

Disclaimer: I have not digested the blog in depth...I'd nee to make more coffee. ;)
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Re: Requicha's algorithm in FreeCAD?

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