How can I get G2 fillet from two curve with Dynamo

I cannot really comment on the Dynamo UI history, I am not part of that team. I do agree that some things there are clunky, but I would hope that this clunkiness goes away over time, with more people using it.

Still, already now you can do powerful things, which I will be evaluating over the next months. :slight_smile:

Hi, GG. I think I understood the questions. For Alias users, we are playing with complex surfaces/structures (for example G2 fillet or draft surfaces with specific draft angles) which can not be done with the existing nodes and Design Scripts elements in Dynamo. But we know clearly how to build in Alias workflow. So if we can use Alias API library in Dynamo Python, we can fix all the issues.

Now the question is: Can we use Alias library in Dynamo Python scripting environment?

Thx,
Yao

Hi Yao,
This is not possible yet, but already logged in our system as improvement ALS-4334.
Thanks,
GG

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Thanks for the reply, GG,
Just want to emphasize again how important it is to have access to Alias libraries in Dynamo. As an Alias and Grasshopper user, I have to say Dynamo is a very promising tool for both car/product designers and 3D modelers, but unfortunately, its ability is still far from enough in actual project scenarios…
Build a better connection between Alias and dynamo could be a practical solution. Just like Revit & Dynamo, Rhino & Dynamo. By the way, Dynamo Player in Alias 2021.2 is already a big step towards the direction we eagerly await.

Very appreciate your work and I have faith in Autodesk products. I believe very soon we car designers can finish all the 3D design tasks In Alias and don’t have to switch back and forth between different softwares.

Yao

Thanks for your feedback, Yao, we are aware that this improvement would be huge. :slight_smile:

Cheers,
GG

Hello!! I have a simple solution about two fillet from two curve. I use the node call “By betweenCurves” But fillet have a lot of spans. and I can’t fix this. So I use the other solution. The solution not really G2 fillet. But is approximate.
Sorry, My English is not good . I can’t explain this. You can look my Dynamo capture



Hi,
Unfortunately, we don’t have access to better fillet functionality from Alias inside of Dynamo yet (this is a known issue).
I am surprised that the result has so many spans. Could you share your Dynamo script here?
Thanks,
GG

It doesn’t work, when the filleted line is not a straight line. In my opinion, if I’m not wrong, you use the curve point as control point.

Grasshopper can get G1 fillet curve, but it can not get G2 fillet curve the same as Dynamo. Still, we can get the similar G2 curve fillet in some way.

OK. This is my file. Create this is not easy by Dynamo. Because create anything always from scratch. Grasshopper doesn’t need.Hexagon_G2_Chord_Fillet.dyn (44.3 KB) Hexagon_G2_Chord_by_hand_Fillet.dyn (74.6 KB)

You’re right. This way only be used straight line. Use curve is not good. Maybe I have to find the curve tangent then create point…

I know grasshopper have the good way create this. and I Hope Dynamo can be better in the future. Because I don’t like file conversion. :joy:

Thanks for sharing the files. I’m pretty busy these days, but I will look into it at the weekend. Will let you know what I find.

Hi, Guys.
I dug a bit deeper into Skitt’s solution. After I adjusted some nodes, now you can Fillet even when the original curves are not straight lines.
But, the blending curves created by the ''Curve.ByBlendBetweenCurves"do have too many Spans, which are not acceptable.
I tried to add a few more Nodes in the script to simplify the blending curves, the result is visually OK.
Anyway, If you need more precise constructions, Please go to my #2 solution in another comment.

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The 2# solution: It is a little complicated, but it works.
With this solution, you can have high-quality fillet curves(5 degrees, 1 Span);
You can have more control over the shape of the fillet curves.
But there are still Bugs:
In this Solution, the original curves have to be 3 degrees. If they are not, you have to change some numbers in the scripts.

Thanks a lot, I will go through it and give you a feedback. However, this is looks complicated. LOL.

Hi, GG.
It is true that the curves created by ''Curve.ByBlendBetweenCurves" node.
I thought the problem should be caused by the data type conversion(when converting a 5-degree “Nurbscurve” to a “curve”).
I did some trial: when I convert “Nurbscurves”(which is very clean, 5 degrees, 1 span) to ''curves", and then convert back to “Nurbscurve” again, the construction of the Nurbscurves changes a lot: got too many spans.
I also tried:

  1. If I convert a 3 Degree Nurbscurve to curves and then convert back to Nurbscurve again, the result is Ok, the curve properties didn’t change.
  2. If I just manually increase the curve degree from 3 to 5 and don’t do any other modifications, the result is also good, the result curves become 3 degrees but still have 1 span.
  3. If I manually increase the curve degree from 3 to 5 and move some control points, and then do the same operation above. The result is bad, too many spans.
  4. Draw 5-degree Nurbscurves directly in Alias, and then do the same operation above. The result is bad, too many spans.

Oh!! Thank you. I know use Dynamo rebuild curve. But the curves point is not curves control point. So I won’t rebuild.

Another my way I send all fillet to Alias layer and rebuild to 5 degree by Alias “rebuildcurves” . But I lose dynamo history.

The second solution is cool . This way you find the curvature point is it?

By the way Dynamo play is very cool. I already created a lot of tool help my work.

Hello, where can I find CurveCrown node…

Hi Yao,

You did some very cool stuff here! :slight_smile: in fact, you implemented your own curve blend! Yes, what you write about the too many spans is true, but sadly makes sense from the Dynamo point of view. So far, Dynamo works similar to Rhino (and probably a lot of other, non Class A CAD systems): whenever something needs to be re-approximated, they do it by simply adding degree 3 spans, until the needed tolerance is reached.
I also totally get that our Alias users shouldn’t have to re-implement the Alias math to get clean Nurbs tools in Dynamo (although, again, hats off for achieving that for curve blend!).
I will give my best to point out the importance of the availability of good Nurbs math in Dynamo to our product management team.

I made it by myself. You have to explode Polycurves or polygons in to curves before using this tool. CurveCrown.dyf (13.9 KB)