Why is this control point spline not fully constrained?

[lichtzeichenanlage]

Hi,

any ideas why this simple spline isn't detected as fully constrained?

thanks and regards

lza

[HughesTooling]

Not sure but when I tried to drag the spline to see if anything moves Fusion crashed. Also missed the collinear constraint you added and tried to add a coincident constraint between the base line and the control point and Fusion crash again.

Mark

[TrippyLighting]

That's a bug.

As can be seen in the screencast Fusion 360 also crashes when I just try to pull around on sketch geometry around the spline area to see if it is really full constrained. I am tagging @jeff_strater and @paul.clauss

Here's the CER report #

CER_176324641

[lichtzeichenanlage]

Ouch, that's even worse. It's not happening on my side. Stupid question: Are you already using the new (2.0.4343) version?

[Phil.E]

Thanks everyone. I can reproduce the sketch drag crash. Now logged. Please respond here if you continue to find cases where this happens. I've notified the sketch team about it.

Regards,

[hpekristiansen]

As of 2019-09-12 there are still problems.

One strange thing is that your sketch is in a sense over-constrained. When you set the control point line to be colinear, the curve is automatically tangent.

If you delete either the colinear or the tangent constraint, the problem disappears and the curve shows correctly in black to be fully constrained.

[Phil.E]

@hpekristiansen Can you post a design that shows this? I can easily constrain (turn black) a CV spline today.

[hpekristiansen]

To clear up some things I did not write properly:

1. Start with the original file from OP with both colinear and tangent constraint. Delete colinear constraint. Everything turns black and seams to work.

2. Start with the original file from OP with both colinear and tangent constraint. Delete tangent constraint. Everything turns black and seams to work.

3. Start a new sketch with similar lines+spline. Add colinear constraint. Everything turns black and seams to work.

4. Start a new sketch with similar lines+spline. Add tangent constraint. Everything turns black and moves to make line and spline tangent. The control point can still be moved, so that line and spline are no longer tangent. -see picture.

[laughingcreek]

@Phil.E , @jeff_strater 

With this thread, I count 3 separate but  current issues/threads related to tangents and splines.  I know I wrestle with spline tangency all the time.  Is this actively being looked at? 

[Phil.E]

@laughingcreek  If you have examples of spline tangency problems please post them, of course we look at them all, test them, log bugs for them, and fix them. 

Regarding the issues described here: I just spent an hour to find out:

1. The original problem is not reproducible. The file can be edited and the sketch is constrained looking.

2. The crash is fixed long ago.

3. @hpekristiansen is correct about the original file being overconstrained.

4. @hpekristiansen can you post the design or a video? I cannot reproduce the image you have posted.

The only bug I can find is that the original design, and new ones like it, can be overconstrained by adding both the tangency and colinear constraints that are referred to here, to a shape like this. Glad to log it, please help me understand the impact it has on you so I can give it the right priority.

[hpekristiansen · Accepted solution]

This precise error does not affect me personally, but there are other subtle calculation errors that do.

(Fusion is great, -the most annoying thing now, is the lack of keyboard shortcuts found in other programs: tab, shift+tab, arrowkeys, cmd+a, cmd+n, ...) https://forums.autodesk.com/t5/fusion-360-ideastation/extend-mac-keyboard-shortcuts/idi-p/9039174