4
$\begingroup$

I want to make a looping animation that looks similar to this

enter image description here

enter image description here

enter image description here

Obviously this is very rushed and the picture doesnt matter but the concept of the paper folding is whats important. I would use shape keys and model it by hand, but trying to keep the plane dimensions consistent without any overlapping geometry has proved to be difficult. How could I fold a plane in this way and have it set to shape keys? PS. It is crucial that while folded, parts of the top side of the plane are visible, in order to make the mad magazine style fold-in illusion.

$\endgroup$
3
  • 1
    $\begingroup$ Wouldn't an armature be a better approach? Similar question here: blender.stackexchange.com/q/239430/107598. The vertices of shapekeys always move in a straight line from their current to the new position. This makes it impossible to rotate them in an arc or bend the mesh more than about 45 degrees if I remember correctly. $\endgroup$
    – Blunder
    Sep 29, 2021 at 11:43
  • $\begingroup$ @Edgel3D Yeah i still need a solution, this looks great! how did you get this working? $\endgroup$ Oct 5, 2021 at 19:01
  • $\begingroup$ I've been toying around with that since, more with a view of you needing to match up surfaces to bring a drawing (texture) together. At the time I was only concerned with developing a viable folding technique, something that should accommodate a variety of cross folding. I've since given each surface a different colour - boy! Did that reveal a jar full of sins! I've sorted all that out and view two remaining 'cheats' as acceptable given your needs. Will write it up and post an answer and Blend file $\endgroup$
    – Edgel3D
    Oct 7, 2021 at 4:33

1 Answer 1

5
$\begingroup$

Multiple Folds Across a Single Mesh

At first glance, separating each section and hinging those individually with bones would appear the most viable way to go, but surfaces are easily deformed, edges get bent and gaps start to appear. Patching those up sounds straight forward, but it's not, particularly when 2ndry folds are introduced. (a fold across an existing one)

Using just One Single Mesh - (Blend file below)

enter image description here

The very first step is to ensure that everything' s scale is "Applied". (CTL-A)

Where-ever a fold is anticipated, an edge (in Edit mode) must also be added there. That includes cross- folds, where a fold runs across an existing fold.

For each fold - The rotating 'handle' MUST be aligned along the edge-line. (intended crease)

Alignment -

Make sure to be in Ortho mode. Use only the view-keys on the numpad - 7,1, & 3 or CTL- 7,1, & 3.
DON'T use the mouse to set a view for alignments.

Make sure the Window's 'Orientation Mode' is set to 'GLOBAL'

The paper mesh should be a flat plane aligned to all 3 global axis' as it would be when first 'added' with SH-A. (alignment is still possible if it's not, but it requires a lot more fiddling. You'd need to align one axis at a time and keep repeating each axis until it's right. Not recommended)

.

A hinge or fold line (crease) would be an edge as seen in Edit mode. Hilite the two end-vertices that make the line and set the 3D cursor to the Gismo with SH-S. (Cursor to Selected)

Add a STRAIGHT 'Curve-Path' to that location with SH-A. If it needs to scaled up to extend and reach the edge-line's length , do that now and make sure to re-APPLY it's scale with CTL-A, but keep it dead straight! If it gets bent, even slightly, replace it.

In Edit mode, place the 3D cursor on one end of the edge line. (as far out as you can)

Back in Object mode and in the Top down view (np 7) rotate the path in the GLOBAL Z axis only, until it intersects with the 3D cursor. (Keys - R Z)

Zoom right up and rotate again so the path is back on the 3D cursor's cross hairs. Keep doing this until fully zoomed.

That will have the path all but perfectly aligned with the edge and ready to be used as a rotation handle (a hinge) for that edge.

Select the vertices that are to be rotated and give them each their own Hook. Don't be tempted to provide a single common hook to rotate multiple vertices. Chances are it will only complicate matters.

Parent those hooks to the rotation handle. (the Path)
(Hooks are the children, the Path the parent )

IMPORTANT - Now set the Window's Transform Orientation to - "NORMAL".

When selecting the path for rotation you will see one of it's axis arrows aligned perfectly with the intended fold's hinging edge. That's the LOCAL axis you rotate. (e.g. R XX and drag the path's rotation)

The hook children will take the vertices they're hooked to in a uniformly swept arc as the handle rotates. If they don't, proper path alignment hasn't been achieved and would need to be redone.

-==============-

Later, it could be that another fold has to be hinged across an already rotated fold line. (cross fold)

Do as before, set up a Curve-Path along the desired edge line. Align it, assign the hooks required as children of the path, and rotate.

Depending on the nature of the fold, you could end up with a kinked surface, but there'll be no gap.
These don't lend well to rendering so make it a point to subdivide and create a new edge directly along the kink. (i.e. fill in the two vertices forming the kink to provide a new and legitimate fold. (F key) You'll need to delete the original face and replace it with the two newies.

.

Other hooks, can be introduced and keyframed to compensate should faces and/or texturing need adjustment, or clipping occurring. Unlike (relative) shapekeys, hooks allow you to experiment all you want without fear of dislodging other hooks. (make incremental saves first)

-==============-

The two arrows in the clip above point to two vertices that are not following physics. The lower has been left as it is and allowed to stretch that section (surface) out as it rotates. This isn't that noticeable if at all and will be concealed anyway. No texturing is involved in that area.

The upper arrow points to a corner vertice that would penetrate the vertical brown surface when folded down, but again because it's not noticable, the surface (section) hasn't been resized and re-hooked. Instead the vertice is simply keyframed to be pulled back as it folds over.

As you can see in the first clip above, this has reshaped that surface and shifted P5's handle alignment significantly. It's not a problem in this instance but something to be wary of in future projects.

$\endgroup$

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .