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I want to be able to simulate a cloth object where some of the edges want to crease to some angle. For example, this mesh below has a line of edges marked seam on the left, and on the right I've used edge crease to highly another line of edges.

before

And I want to be able to tell Blender that the seam marked edges should be bent to 90 degrees, and the creased edges to be bent to -90 degrees, which the following picture illustrates.

Thanks!

after

I tried to do this once years ago using a sort of genetic algorithm sort of approach, and shape keys, with mixed results, then last night a friend suggested I try cloth simulation, which seems much more promising.

I don't care if the solution has anything to do with seams or creasing, just so long as I can have Blender know it should bend part of a cloth object to some angle.

Edit: I want the physics simulator to do the bending for me, so for example, I would make the original flat mesh, and add something so it would know the edges should be creased to some angle, and then the simulator itself would do the bending for me along the edges as I've defined, to the pre-defined angle.

A Second Edit: What I'm trying to simulate is the way paper folds, as in this video here: https://www.youtube.com/watch?v=2Q-A38tK4SA The video depicts the result of folding concentric squares into a square piece of paper, which causes it to turn into a saddle, or potato chip shape. I can rig up bones to bend the "paper" model in Blender, but I want Blender to actually do the saddle-shape deformation, based on the fact that the model is creasing.

This is a rigged plane:

rigged concentric squares

And notice it doesn't reproduce the saddle shape. I think it would be area preserving that would mimic paper, since paper can't stretch or shrink, but I don't think volume preservation will work right.

the posed result

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You should probably use pinning for this. If I understand correctly what you want vertex groups will allow you to define parts of the mesh not altered by the cloth simulation.

Select a few corner vertex, as many as you need, the more selected vertex the stiffer the animation will be, and assign them to a new Vertex Group.

enter image description here

Use that vertex group for pinning under the Physics > Cloth > Pinning. You can use this in conjunction with shape keys and animation to drive the shape from flat to folder or similar.

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  • $\begingroup$ It's not quite what I'm trying to do—I don't want to pin things in place, I want the cloth simulation to add the creases. So I would start with the flat model, and the physics simulator would do the creasing part for me (after I define somehow what edges should be creased and to what angle). Thank you for the suggestion though. $\endgroup$
    – Cody Reisdorf
    Oct 30, 2017 at 2:32
  • $\begingroup$ Maybe instead of cloth I should be looking at the soft body physics $\endgroup$
    – Cody Reisdorf
    Oct 30, 2017 at 2:36
  • $\begingroup$ Re-read the last part of my answer specifically the "You can use this in conjunction with shape keys and animation to drive the shape from flat to folder or similar." Just animate the position of the vertex $\endgroup$
    – Duarte Farrajota Ramos ♦
    Oct 30, 2017 at 2:57
  • $\begingroup$ Yeah, I don't want to animate the position of the vertex, I want the physics simulator to do it, so that they obey certain constraints. $\endgroup$
    – Cody Reisdorf
    Oct 30, 2017 at 3:10
  • $\begingroup$ Well you can animate any other object like a thin rod set to rigid body to form up those creases using physics, but I fear the result will be practically the same $\endgroup$
    – Duarte Farrajota Ramos ♦
    Oct 30, 2017 at 3:14

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