Subdivide, insert edge, ... create strange folding artefacts near outer edge

[dunderhead]

Hi, I've tried to use a subdivide strategy for constructing a T-spline mesh (to become brep surface) that approximates an STL mesh.  That led me to discover the following problem: when you subdivide next to the outer edge you'll likely end with unexpected folds. I've come to the conclusion that the tangency handles of the verts along the edge loop are not updated, see below. This holds for other elementary operations as well. But why not? Keeping the same tangency handles for the smaller face makes little sense (if that's what's going on...).

/dh

[shilei.zhang · Accepted solution]

Hello, Dunderhead,

Thanks for reporting this and sorry for the inconvenience you have met,  here is a solution might be helpful for you to get rid of those folds.  please check the pictures i posted below.

Select the T-spline plane or a patch of the plane and invoke Editform in the RMB menu, choose "Vertex" in Selection Filter ( Alt+A) ,and you will see some pink control points ( the same as those in your picture)

Window select all the pink control points and you will see an option called "Link tangent handle" in the Edit form dialog.

Click the cute button which looks like a chain to link those handles, after that those pink points will become green ones.

And then you will probably not encounter the folds on your models anymore, which means you could try to check if there is any pink handle in your model when you see folds again.

Please feel free to let me know if you still have any query.

Cheers.

[dunderhead]

Thanks Shilei: I understand now!

The behavior that results from the handles is undesirable in common use I think.  It seems that Fusion already anticipates this! For example, these handles don't appear for faces that belong to a plane (something constructed with the 'plane' command).   So, I think Fusion 360 tends to make the tangent handles (also called "grips" I gather) "linked" by default. And once they're linked you can't unlink them, which may be fine (?).

Is there way to use the 'face' command so that the tangent handles are not added, in other words, I'd like the 'linked' state as the default? I imagine there should be a 'link handles' box on the 'face' command, normally checked?

/dh

[shilei.zhang]

Hi, Dh,  

I am so glad my answer worked for you.

As for the "face" command,tangent handles are not linked by default,  actually, this is not percifically just about "face", you probably will meet this issue with some other commands, because sometimes ,adjusting those handles is helpful for shaping your model even they are not linked.

But to be honest, not just you,some other users also feel like default linked handles would be less confusing, we already got some suggestions like this in the Idea Station, and i assume that adding a "link handles" box on the command dialog to offer an option would not hurt, maybe someday we could see this option in future release. But before that, once you have such problem with folds or unexpected shapes, try to check those handels.

If you do have some ideas or suggestions and you want to share with us, please login to idea station and post them, we 'll be full of gratitude.

Cheers.