Inflate an irregular box

[sofia]

Hi all!

I want to create something similar to my sketch below, an irregular box that looks inflated (making the sides slightly convex). The first steps seem quite straight forward; Sketching the outlines of the box using spline in a 3D sketch and adding points that will be the second profile when using loft to create a convex surface. The first loft works but not the second, the splines doesn't create a profile. It seems like the problem is that the curves move through different planes. Is there any way around this?

Preferably by working the solid mode rather than surface mode:)

Also, is there a command to move a point in the center of an irregular profile?

Many thanks,

Sofia

[jeff_strater]

This looks exactly like a job for T-Splines (Form features).  "Pillow" shapes are what T-Splines are best at.  The Box primitive is pretty much exactly what you are trying to create:

If the body is closed, it will be converted to a solid when you exit the Form workspace.

[TheCADWhisperer]

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@sofia wrote:

Preferably by working the solid mode rather than surface mode:)

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What's is wrong with Surface modeling?

Can you File>Export your *.f3d file to your local drive and then Attach it here to a Reply?

[sofia]

Yes, perhaps time to start working with surfaces. I worked in Rhino before and that sort of put me off, errors with not joined surfaces etc.

I developed the sketch a bit to get closer to what I am after, pls see attached.

Many thanks,

Sofia

[sofia.winberg]

Hi Jeff,

Thank you for introducing me to the form workspace. Indeed the box looks very similar to the screenshot that I uploaded. I should have been more specific however since I would like the irregular box to be asymmetric with differently curved and scaled edges. I tried this in the form workspace by starting with a box and then edit the form and curve but without reaching the result I wished for. It might be too intuitive for this project since I would like to easily control each side view and also the curvature of the loft/face (eg how pointy it should be).

Kind Regards,

Sofia

[jeff_strater]

@sofia - you should be able to achieve the results you want with T-Spline, there are lots of controls there, but it does take some practice to get exactly what you want.

[TrippyLighting]

I agree with @jeff_strater

This is a t-spline project all day, every day.

[sofia]

Hi Jeff,

I can pick the tangency weight with the loft command, is there anything similar in the form workspace? 

When moving a center control point the sides become to pointy (even if using the soft modification > bulge).

Modify> crease worked for getting sharp edges. So only thing is how to create that soft bulge while keeping the edges sharp. Please see attached illustration.

Kind Regards,

Sofia

[TrippyLighting]

We really need to have access to your 3D model. Please export as .f3d and attach to your next post.

To answer your question: T-Splines don’t need tangency handles.

[jeff_strater]

Thanks.  The sharp edges was not something I picked up on at first.  But, yes, Creasing the TSpline edges will get you that.  Regarding "too pointy", yes Soft Modification is the tool to use to prevent that.  Can you elaborate on why Soft Modification doesn't work like you need?  You can tweak all the parameters and affect how the modification affects adjacent faces.  There is also the "control" of the number of faces in the TSpline body.  The more faces you have, the more shape options you have available to you, but the downside of that is you have more faces to deal with.

I'm not sure I understand the reference to tangent weight in Loft.  Since you want sharp edges, how do you see using tangent weights?

Of course, there are many ways to get a design like this.  You can do it with Loft (solid or surface), or with Boundary Patch, and probably many other methods.  In the end, you just need to choose the one that feels right to you.  For me, for what I understand are the requirements, I would still use TSplines, but that is just my preference.

[sofia]

Hi,

Sorry for late reply, I have tested sketching the box but failing in how to think around making it irregular and still keep the edge points at the same plane. I have uploaded the f3d file here and also a screenshot of a sketch.

Basically I would like to keep the front fixed and then move the bottom two corners at the back to where the free-standing points are. I don't know how to lock lines/points so they are all moving together, if that is the solution.

I will go on trying the form workspace as well.

Kind Regards,

Sofia

[sofia]

Hi Jeff,

Thank you for your reply. I can choose the shape of the convex face by using the tangent weight in the loft command. In the form workspace the weight input doesn't effect the convex shape at all what it seems like, see screenshot.

Also, I find it hard to reshape the form whilst keeping the face on a construction plane eg without having it twisted. This before giving the box it's convex shape.

Kind Regards

//Sofia

[sofia]

Hi, 

I finally got the box in the solid workspace by using draft, construction planes and loft. However the result didn’t turn out that nice so I went back to the form workspace. There I used edit form>rotate to get the irregular shape, thereafter crease and thereafter edit form>move to move faces and create the convex sides. To my question; Is there any way to get the direction of the move be perpendicular to the face? Now it moves within the directions set by the origin, resulting in geometry that looks disoriented.

@jeff_strater @TrippyLighting @TheCADWhisperer 

Kind Regards,

Sofia

[jeff_strater · Accepted solution]

Great question.  This is where this row in the Edit Form dialog comes in:

There are 4 modes here.  The first is the default, which is World Space, where the manipulators are oriented to the global XYZ.  The second is View Space, where the manipulators are oriented around the view (so it changes if you rotate the view).  I don't use that one so much.  The third is probably the one that is closest to what I think you want, which is "Selection Space", where the manipulators are oriented around what is selected.  The fourth is called "Local Per Entity Control", and I can never remember what it does or why it is different, and I NEVER use that one at all.

Give Selection Space a try!

[sofia]

Thank you so much @jeff_strater , it worked perfectly. Will definitely start working more in the form workspace.

Kind Regards,

Sofia