Bug with conic curve and constraints

[soswow]

Hi there

Just woundering if this is a known issue? 

I see similar reports way back in the past: https://forums.autodesk.com/t5/design-validate-document/conic-constructions-exact-equations-finding-... and not sure if this was reported correctly before.

Here is a video, that would demonstrate it:

In different design when I selected an end of a line (which were partially constrain on it's own) and my curve, it didn't even allow me to select any of the constraints (like coincident):

[soswow]

Seems like when all three point of conic curve are fixed it snaps where it shuold. But I don't want those points to be fixed.

Another question. Even when they fixed seems like I can't constraint a line to be tangential to a conic curve. IS this a feature or a bug? Seems like this is only works for it's edges.

[soswow]

Would love to get some comment from dev evangelists 

[promm]

@soswow,

There seems to be an issue with the conic curve when you drag from the point where the line and curve connect.  Our development team is looking into the issue.  I have created a video that shows how you can create a line tangent to the curve.  Best practice is to constrain at lease one part of the curve, this allows you to drag and evaluate the design while keeping the movement predictable.

http://autode.sk/20SsEla

Cheers,

Mike Prom

[soswow]

Thank you for your asnwer!

I actually already said, that tangent constraint for it edges ("Seems like this is only works for it's edges.")

But I was interested more in snaps and constraints at any point on a curve.

I've made another video. You can see, I fixed all three points of conic curve, this allows perfect snapping. that's good. This would be enought for what I need in this regards. What's missing is tangent in between edge points.

[ShirleyShi · Accepted solution]

Thanks, soswow, what you show in the video is a bug for Fusion. I have logged FUS-22758 to track it.

Thanks,

[soswow]

I just randomly check in the last update. The bug is still there in the product. How is FUS-22758 going? @ShirleyShi

[Phil.E]

@soswow

Hi thanks for asking. Looking into the report I see it's open and not fixed. I've asked for an update.

Regards,

[vogeljames]

Almost 1 year to the day, I'm having the same issue with conic curve constraints. 

I'm guessing that this has not been fixed yet, and it is still an open issue?

[mroek]

I just came here to report issues with constraining conic curves, and found this thread. It is extremely disappointing that this hasn't been solved in almost three years after reporting.

@Phil.E @ShirleyShi @promm :

Any chance of getting this fixed in the near future?

[rohit.bapat]

Hello @mroek and everyone interested in this forum topic

I agree with you that this issue had taken a back seat for some time. I am going to take this ticket to the team to take a look at. The timeline for fix will depend upon the effort needed for the fix. But, surely we will keep it on our radar.  

Also, I am interested to know how conic curves are used in your designs, for example, how do you use conic curves in you solid or surface modeling? This information will further help us understand if there anything more we need to worry about.

If you don't wish to put the design information on the forum you can contact me through my official email id rohit.bapat@autodesk.com

Looking forward to working with you all and make Sketch more reliable

Thank you,

Best Regards

Rohit Bapat

(Product Owner, Fusion 360)

[soswow]

@rohit.bapat 

To be honest, my reply might not help here, since it's obviously very special 🙂

I was modeling a parabolic mirror system device. So In my scatch, I wanted to plan light rais hitting a parabolic curve.

[mroek]

@rohit.bapat:

I don't use conic curves all that much, but in this instance I was after a parabolic curve to create a RF antenna reflector. I noticed that even though the curve was fully constrained (and turned black), it would still move around when connecting other sketch curves and dragging those. The only way to fix that was to use the fix constraint, which I usually avoid.

So this was more a knee-jerk reaction from me when I came to the forums to report that bug, and then found it had already been reported years ago, but nothing done about it.

And while I'm at it, it would be nice to be able to use the tangency constraint somewhere along a conic curve (and not just the ends). For a parabolic curve it would also be nice to have an indication of where the focal point is, although that can be determined by adding the proper construction geometry. Provided the conic curve doesn't move around even if being fully constrained, that is...

[lure23]

Thanks @rohit.bapat for bringing focus to this.

I came across it today in my work and like the creator of this post, wanted to check if it's a bug or not.

My intention (screencast below) is to model an arc based on structural optimization mesh. At the top of the arc needs to be a flat top bar.

1. I tried dimensioning between the top line and the conic curve. This isn't possible (if it had been, my need would have been fulfilled).

2. So I went for making an additional line (to the right; should be a construction line) and thought to make a tangential constraint between it and the conical curve. As you can see, the line drops down, and isn't actually tangential (though Fusion 360 claims so by having the tangential constraint icon attached).

Thanks for your words "Looking forward to working with you all and make Sketch more reliable". Consistent reliability and consistency of underlying features is terribly important and I appreciate you personally bringing light to this, within Autodesk.

Also, I feel the company could focus on more urgent delivery of fixes that have been taken in the ticketing system (i.e. confirmed and accepted to a roadmap). In addition to this, Curved Slider Joints (FUS-26127) was taken in around 3 years ago. If lack of being able to proceed with these is a business decision, please raise it up internally. No-one benefits from long turnaround times. Such fixes may not be fancy on slides, but they matter to everyday use!

Apple had this once. They made a whole Mac OS X release that was focused on stability and getting the underbelly right. Then they pushed on for more features. Be brave in pushing for the ticketing cleanup!

[mr.rickwright]

@rohit.bapat 

The Conic Curve has multiple weaknesses that reduce its usefulness.

1 the constraint issue in this thread

2 the issue that Rho is not a parameter and cannot be used in a formula or derived by a formula and cannot appear in User Parameters.

3 Mirroring - if you mirror a conic curve and change the Rho then the mirrored curve does not adjust.

I design Kayaks and the conic curve is very useful for the Section Profile used for Lofting the shape, but the above issues make it frustrating to use. Example is attached.

If Rho was available in the parameters and the constraints and mirroring worked it would make the design process much better.

Rick W

[shadewind]

I very much agree with this. I immediately ran into these issues when using conic curves in Fusion 360:

https://forums.autodesk.com/t5/fusion-360-support/dimensioning-conic-curves/td-p/9258370

To me it is a severe limitation that Fusion 360 doesn't seem to be able to properly solve for arbitrary constraints when using conic curves. Overall, I expect every kind of constraint to work with every kind of sketch element where applicable as long as it is possible to solve mathematically.

[tlmassey]

Six years after this ticket was reportedly entered,  has it still not been addressed?  If conic curves can't be constrained, then they effectively cannot be used in any practical design.  I'm trying to come up with suitable approximations with other constructs, but I'm not pleased with the results so far.  @rohit.bapat, are there any updates from the dev team?

My two cents as a user/engineer:

If a feature is drastically incomplete, it's better removed than left to confuse users and waste their time.

[mr.rickwright]

I gave up using Autodesk because several of the issues and bugs I encountered when trying to use parametric driven design were never addressed. In the software I am now using I was able to create my parametric driven designs in much less time with much less frustration. And they work.

[laughingcreek]

@mr.rickwright -what software are you using now?

[Phil.E]

Constraints that work with conic curves:

• Tangency
• Coincident (at end points/center point)
• Horizontal Vertical (at end points/center point)

Most of the other constraints do not seem useful for conic curve. Can you help me understand what sort of constraints you wish to use with conic curves that are not working for you? Help me understand your workaround(s) and I'll be happy to log improvement tickets, but at this time I don't see much room for improvement.