How to make a fold while following a circle edge?

Question

Hi. New to Blender, so appreciate any help possible. I'm working on a yoghurt pot render (not the one shown), and the seal cover under the clear lid is a typical thin foil cover with a tab so as to pull it open. The image on the left is an example of what I mean. The dieline I'm working with is shown in the centre. As you can see the tab folds down from a section of the circular foil cover.

What is the best way to do this? I've already drawn my circle and extended the vertex on the X axis to create the square edge as a flat shape, but now want to fold this part down. Is it possible in Blender to rotate the tab section so that it folds along the edge of the circle, shown as a dotted line? I understand about moving the pivot point, but that's not working for me as it's only pivoting off one vertex point and not an edge, and is doing weird stuff to my shape.

An alternative would be to extend the vertex down 90 degrees on the Y axis, then adjust the heights of each vertex to get the basic shape and add a subdivision surface modifier and tweak with edge loops, but I was wondering if its possible to rotate/fold around the circle edge. Cheers.

Answer 1

It is possible to fold along each edge with an armature. But it will not preserve the shape of the tab, because it is not geometrically possible.

Here is the fold result:

On a real yogurt, there is not one clean fold, but many folds.

In the image above, sort of 3:

What you could do is some manual folding (guess work). You could use the pivot point, or the armature technique, to get several folds along straight lines (the only ones that will preserve the shape). It will not be perfect as I think you thought it would be, but it can't.

Some dirty work using the pivot point:

For making it better you could use an armature, and cut your straight lines with the knife tool.

Other way: fake it. It would not be correct, but if you only want to get the folded yogourth (no need to animate), you can select the rim, extrude it downwards (Z axis) and make the angle with the proportional editing turned on (connected) while hidding (H) some vertices in order to keep the upper part from moving. Here is an example result:

And after some work you could get this kind of topology:

It is not accurate to a real folded peace of paper, but it looks good.

Answer 2

If I understood the question. I have found 2 answers for it.

Answer 1

1. Add a circle and go in edit mode and press F to fill faces.

2. Add a plane and go in edit mode and press W and subdivide once.

3. Delete 5 vertices and just have a square shape below.

4. Select the square and circle and press Ctrl+J (Join).

5. Go to edit mode and select the corner of the plane and press Ctrl+Shift+B (Bevel) and with the mouse wheel scroll to get segments.

Cleanup Geometry

Go to edit mode and select the verts of the curve and remove doubles and then Press F to fill faces.

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Answer 2

1. Add a plane select to edges and Mean crease in the Properties panel (N) in edit mode.

2. Add Subsurf modifier view 6.

3. Add a cloth simulation with default value.

4. Smooth shading

5. Add a base cup shape and in physics panel add collision to it.

6. Play and stop the animation at a point where your satisfied.