Spline not editable in 3D sketch

[Anonymous]

I've been encountering some VERY frustrating problems within 3D sketching, specifically with editing & assigning relationships to splines. The real puzzle is the problems only occur half of the time.

To demonstrate the issues, 

1. I created 2 surfaces, and drew a 3D spline snapped to the corner of the surfaces, then assigned curvature relationship to the edges like below:

2. When I use the move command on the handles of the spline, SOMETIMES they wouldn't move, Here's what it looks like: everything stays in place as I drag the arrow.

But if I delete one curvature relationship, the handles become editable again.

2. I delete the curvature relationship on one end and try to reassign it, all of a sudden it won't work, when it just did before???

These types of inconsistencies are driving me nuts... anyone has any idea what am I missing?

Thanks!

[rohit.bapat]

Hello @Anonymous 

I can observe a couple of things here.

1. The spline has only two fitpoints. Normally a G2 (curvature constraint) demands more fitpoints to get aligned properly. According to me because of lack of fitpoints, when you move the end point of the active handle spline doesn't get any freedom to adjust the shape. 

2. Regarding the second issue where the curvature constraint doesn't get applied. Can you please make the tangent handle inactive again and try to add the curvature constraint? 

These are just my observations based on the images, if you can please attach the f3d file we will be able to help you better.

Thank you,

Best Regards

Rohit Bapat

[Anonymous]

Hi Rohit, thanks for your help on this.

I just went ahead and tried the spline with 3, and even 5 control points, but the same thing happened, and the curve is even crazier =(

Your second tip seemed to help, was able to assign curvature relation I after deactivating the tangent handle. The problem is it'd be in the opposite direction, and moving the handles again behaves very strangely - jumping huge distances / moved during move command preview but snapped back after clicking OK / moved successfully but can't move again (back to problem 1).

I'd really like to fully understand what's going on here as my projects rely heavily on these types of features.

Thanks for your help on this again!

[rohit.bapat]

Hello @Anonymous 

Thank you for your input. This will be helpful for us while debugging the issue. I think we will need to take a deep dive into the issue to understand what is happening?

Could you please send the file to us so that we can take a deeper look into it? If you don't want to share the file here you can send to me via my work email id rohit.bapat@autodesk.com Your data will be kept safe and secure according to our safety policy.

[Anonymous]

Attached is the test file from my screenshots, thanks again.

I also sent an email to you about a sperate performance-related issue that's been impacting our productivity (I work at BIRD), hopefully you can give some insight on that as well.

[TrippyLighting]

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@rohit.bapat wrote:

Hello @Anonymous 

I can observe a couple of things here.

1. The spline has only two fitpoints. Normally a G2 (curvature constraint) demands more fitpoints to get aligned properly. 

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As far as I know a fit point spline in Fusion  360 is a 5-degree multi span spline. There should be no need for more fit points ?

Even if you’d have only a single span curve, as a 5-degree curve it has 6 control points (not fit points). That’s enough to make it G2 at both ends. No ?

[rohit.bapat]

Hello @TrippyLighting 

Yes, it is true that fit point spline is internally a degree 5 spline and I agree with you. I was focussing more on the tangent handle behaviour and its impact on the spline. I just wanted to rule out some of the possibilities with strange behaviors related to Active Tangent handle. According to me something, somewhere, somehow (which debugging the file can reveal) the spline solver is not getting enough freedom when it comes to moving the point of active tangent handles.

So theoretically, yes a fit point spline shouldn't need more than 2 points but if you see @Anonymous  finding with more than 2 fit points the solve is even worse. So something is going off while solving. This is where I am sort of coming at that, what we need to investigate is that why with active tangent handle, a two-point fit point spline is not getting solved properly in general with G2 constraint?

According to me, it's a simple case that may reveal a generic issue, a solution to which can benefit in many situations.

Thank you,

Best Regards

Rohit Bapat

[TrippyLighting]

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@rohit.bapat wrote:

According to me, it's a simple case that may reveal a generic issue, a solution to which can benefit in many situations.

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I've come across this same issue in each of the last three projects that required a simple 3D blend curve. This is also either a really old issue or simply very frequently reoccurring issue. 

I apologize if my attitude comes across as rather forceful and perhaps even aggressive!

This 3D spline issue renders Fusion 360 virtually useless for all but the most simple surfacing tasks. Generally surfacing and interactively developing shapes in Fusion 360 works beautifully and fluently and is really enjoyable if it would not be for this issue with 3D splines and G1 an G2 constraints.

It obviously doesn't happen with each spline, but when it does it has a devastating effect on the workflow, because there really is not workaround for it. Blend curves are absolutely essential!

If you need more data / design files I can see if I can dig out one of the cases where this recently happened.

[Anonymous]

Glad to hear that I'm not alone with this issue! For the longest time, I just assumed it was a user error on my part since they do work from time to time...

Really, really hope these features can be as robust as Rhino or even just SolidWorks.

[rohit.bapat]

Hello @TrippyLighting 

Sure, no need to apologize. I understand the frustration we are constantly trying to improve Sketch over the years. It's just that some times some issues get more priority than others. I look at bugs as opportunities for improvement. But, definitely, we will try our best to make Sketch better every day.

It will be very helpful if you can send me those files through rohit.bapat@autodesk.com

Thank you, for helping us improve Sketch!

Best Regards

Rohit Bapat

[TrippyLighting]

@Anonymous  you do know that you can do this with a 5-degree control point spline?

It is certainly also not a pleasant experience but it does work (sort of):

[Anonymous]

That's pretty cool, thanks for making this video I'll use this method from now on.

Really wish Fusion is more robust, for example when I work with an imported STP file with 100+ bodies, box select/move multiple parts crashes the program 100% of the time... Haven't found anything that helps with this issue.

[jeff_strater]

"when I work with an imported STP file with 100+ bodies, box select/move multiple parts crashes the program 100% of the time"

Can provide an example design that shows such a crash?  Do you actually get a crash report dialog?  Are you sending those reports in, with your email filled in?  I did a search, and the last crash I see from your email is from July 2019.

Remember, an operation that takes a long time to compute is NOT a crash.  If you are moving hundreds of bodies, you can expect it to take some time.  You are asking the software to do a lot of work.  Depending on what you are moving, geometric complexity, any assembly constraints applied, etc, such a move operation could take several minutes.

[Anonymous]

Hi @jeff_strater 

I appreciate the response to this. To answer your question, I've been using my company account that's why there haven't been any crashes under this account.

Crash might not be the most accurate description, it's more like an indefinite freeze 'Not Responding' status and I can only force quit. It occurs even when I box select ~10 bodies.

I'd be very happy to provide a few files where I encounter performance issues via email since they do contain sensitive IP. In fact, I previously wrote an email to rohit.bapat (who also replied to this post) but has not heard back yet about what's causing the issue.

[rohit.bapat]

Hello @Anonymous 

Thank you for reminding. As I mentioned in my reply, I have taken it to the development team. There are two internal issues we are seeing on our side. We will need to investigate more before we can conclude and find a solution to the bugs.

Thank you,

Best Regards

Rohit Bapat

[jeff_strater]

it seems that we are discussing two separate issues here.  One is a 3D sketch issue, the other seems unrelated, in that it involves moving bodies.  @rohit.bapat is the correct person to look into the first one, for the performance issues, if you can send me a sample, either here as an F3D or via a shared link to the A360 design via Direct Message, whichever is easier.  Also helpful would be a video showing the operation which is taking a long time to complete.  Thank you.