[acyou]

Nice work!!

I tried to run it, but got an API Error:

Due to some internal changes made to the Fusion API, the Add-In: 'sketch_helper' from 'Hestus, Inc.' cannot be loaded. You need to install a new version of the Add-In that is compatible with this version of Fusion.

Can you just put it up on the Autodesk app store?

I struggle with this model, because of the capture by Autodesk and the other CAD providers. If you read the Autodesk EULA, I think it prohibits use of any open-source software in these add-ins. And I don't think anyone can use this software outside of Fusion 360. And if this add-in becomes popular, Autodesk can trivially release something that has the same functionality, built into Fusion 360 by default. And, as you are no doubt painfully aware, the Fusion API can be limiting.

If you can have your LLM ingest a non-parametric CAD model and spit out a parametric model with a beautiful, complete, editable feature tree full of Extrudes, fully defined parametric sketches with these nice constraints, all tied to the sketch origin, now that's something.

I think Autodesk BIM is $5000/mo/user, Fusion is $500/mo/user. I have thought that means the money is in architectural/structural.

As a side note - one other tip I have, for all CAD users everywhere: avoid Tangent relationship wherever possible! Stick to vertical/horizontal on the lines and arc endpoints, and you will be golden. The Fusion sketch solver is badly compromised, it can't do more than two or so simple successive Tangent relations without bugging out. And, my experience with Solidworks is the same, not sure if this is still true.

Curious if you dealt much with the Fusion constraint model, and have any insights into why it works so poorly, or even how it works? Many times, you click on a line, and it turns from blue to black, and back to blue again.

[delhanty]

> The Fusion sketch solver is badly compromised, it can't do more than two or so simple successive Tangent relations without bugging out. And, my experience with Solidworks is the same, not sure if this is still true.

In my experience of building a sketcher at D-Cubed for a consultancy client (1995-2000) on top of D-Cubed's DCM, this is because DCM's curves (which are unbounded BTW) are not directed so that there are lots of erroneous solutions to attempting to constrain G1 chains of tangent bounded curves. For example the Apollonius Problem [1][2] of 3 tangent circles/lines has 2^3 = 8 solutions. IMO if John Owen had chosen directed curves for DCM then dragging configurations of tangent circles would be more stable.

I'll end with a quote from the Preface of Julian Lowell Coolidge's 1916 "A Treatise on the Circle and the Sphere" [3]:

> Among the cartesian theorems there is a sharp sub-division between those where the radius is looked upon as essentially signless and those where a positive or negative radius is allowed.

[1] https://mathworld.wolfram.com/ApolloniusProblem.html

[2] https://observablehq.com/@d3/apollonius-problem#

[3] https://en.wikipedia.org/wiki/A_Treatise_on_the_Circle_and_t...

[acyou]

Thank you for the great response, that does mirror my experience, those tangent curves want to flip/change direction.

I can't believe that all of Fusion, and many other CAM software, is built on such a shaky "sketchy" foundation. It seems that in general 2D sketch constraint models are far from solved in computer science, this seems ridiculous as such a basic and elementary problem. It should be so obvious that the tangent doesn't want to go back on itself to create zero thickness geometry.

Wonder if the 2D sketch experience is much better in Onshape, NX, Catia, etc?

[delhanty]

> Wonder if the 2D sketch experience is much better in Onshape, NX, Catia, etc?

Well those systems and pretty much all of the mechanical CAD industry is built upon D-Cubed's DCM, so I'd expect the behaviour to be the same.

If I was creating a new 3D CAD system from scratch now I'd probably license Parasolid eventually, but I'd pass on DCM.

I don't want to dump on D-Cubed and John Owen though. I have huge respect for him and the company he created. This is technical criticism with the benefit of hindsight.

[hobofan]

> If you read the Autodesk EULA, I think it prohibits use of any open-source software in these add-ins.

That would have surprised me, as most add-ins I am using are open source and the most popular Fusion apps state that they are open source in their store listings and shouldn't have passed reviews if that were the case.

I took a look at the publisher agreement and it does have this section:

> no Open Source Software is or will be included, incorporated or embedded in, linked to, combined, distributed, or made available with or used in the delivery or provision of Your App in a manner that could cause any Autodesk Assets to be subject to any Open Source License.

There is also a definitions section about this that specifically goes into detail about copyleft licenses, so it seems like they just want to stay very clear of the issue of "copyleft poisoning" and exotic licenses, and ensure that if there is any breach of software license terms that liability is on the add-in author.

[delhanty]

> And if this add-in becomes popular, Autodesk can trivially release something that has the same functionality, built into Fusion 360 by default. And, as you are no doubt painfully aware, the Fusion API can be limiting.

This is always the problem with add-ins like this as a business - you're essentially doing free market research for the application vendor.

[kevinsane]

Yes. We messed up, if you redownload hopefully it will work! I'm sorry about that

[acyou]

Still didn't work for me. I think it's stuck in my system now.

I think Fusion copies the add-in to a different directory, which I need to go find and manually delete. These add-ins should really have a Windows Installer function so that I can run the uninstaller to remove it, or have it run the uninstaller when the add-in loads or something to wipe the old files.

This is part of the problem with these add ins in general. I just installed this thing on my computer, I can't see the python source code, and what did I install and run??? Even if I could see the source, I don't have time to read it. That's why they have the app store, so that it can get reviewed to make sure it's OK. Any reason why you didn't just publish on there?

I should really take the advice of the old guys who say don't trust it if you can't see the source. I'm sure you mean well, but I would feel better/safer if it was open source.

Is there anyone who has made an AI LLM that reviews source code or an installer that you want to run and tells you if it does anything problematic? Would that also work on compiled Python source code?

Curious if you linked to the Python libraries, or copied them in with the add-in? Or were you able to avoid most libraries for this?

[acyou]

I looked up that error, I don't have any experience with compiled python code, but this is interesting:

Script Error

The message you received results from an add-in loaded on your machine that has compiled Python code that will be incompatible with the next update of Fusion or is incompatible with the current version of Fusion. This message is displayed when Fusion upgrades to a newer version of Python, and add-ins compiled against the previous version will no longer work.

If the message says, "The script will not be supported in the next version.", this is a warning telling you Fusion will no longer be able to load this add-in with the next Fusion update. When you get the update and the add-in quits working, you'll need to get an updated version of the add-in from the Autodesk App Store or directly from the app developer. Unfortunately, you can't preemptively get a newer version because the new version of the add-in will not function with the current version of Fusion, you will need to wait until after the update.

If the message says, "The script is not supported in the current version.", this is an error indicating Fusion could not load the add-in. You need to get an updated version of the add-in from the Autodesk App Store or directly from the app developer. App developers are contacted to let them know they will need to update their apps to be compatible with the new Python version, and the updated apps should be available as soon as the Fusion update goes out. If an update is not available, you should contact the app developer. App Developers

If you're a developer of an add-in for Fusion, use Python, and deliver any pre-compiled modules (.pyc files) with your add-in, this update will break your add-in. It will be broken because pre-compiled modules are tied to the version of Python used to compile them. Add-ins compiled with the current version of Python (3.7) will not be compatible with the updated Python (3.9) and will fail to load. This change DOES NOT affect any add-ins that do not deliver any pre-compiled modules and the.py source code is available. For detailed information about what you need to do to update your add-in and have it available for your customers at the time when the Fusion update goes out, see this forum post with the latest information.

Then it links to this, which is talking about Python 3.7 vs. 3.9.7, but that's from 2022: https://forums.autodesk.com/t5/fusion-api-and-scripts/import...

Would you need to release the source code then? Would there be the same problem with C++? How can people develop these sorts of apps without having to release the source code?

I'm on Fusion 2.0.19994 x86_64