How to make a paper rigid?

[Anonymous]

I have a paper folded to make two flaps A and B.

If I rotate the flap A a little more, then It will just pass through the flap B.

I want to make the paper more realistic so that it pushes the flap B instead of passing through the flap B.  

But the first step I want to accomplish here is to prevent the flap A crossing the flap B, i.e., the rotation just stop when it touches the flap B even though a larger rotation is given to it.

I would appreciate very much if anyone direct me how to solve this issue. Thanks.

[JuanLopezEgea]

Have you tried with ncloth mesh (painting flexible and rigid parts)?

[Anonymous]

No, I haven't tried.  Is there an example how to do that on www?

[Anonymous]

Painting flexible and rigid part is likely to be irrelivant since I need to make the paper to be all rigid.

I want to make the flap A to be the active rigid body and the flap B the inactive rigid body if they are two different objects.

But this has to be worked within the same object.  So this is totally different from the interaction of two objects.

[_sebastian_f]

depending what else will happen in you animation it could also be worth to think about creating blend shapes and just fake the collision. seems faster and more easy to me.

[Anonymous]

I know it might be easy using blend shape but I need to solve this problem once and for all.

It is an intrinsic problem of having flaps crossing each other and I want to find out a way to prevent this by making a paper rigid.

If I can make a paper rigid, then I can use cluster deformer or blend shape to simluate paper folding without any headache of dealing with layer crossing. 

[_sebastian_f]

any luck so far? interested to hear what you find out.

in the meantime i did a quick test rigging a sheet of paper with joints, using a duplicate of it and make it ncloth, connect the shape of the rigged mesh to the nClothShape (this way i don´t loose the skincluster). the rigged mesh can now selfcollide.

the default result is somehow ugly and i will not show it public but maybe thats a way to go for you.
i´m still not sure if creating your anim this way makes to much sense. i don´t think it´s a do it once and forget about it workflow. you will have to paint a lot of weights - maybe even specific for different ways of folding.

[Anonymous]

I tested your method utilizing nCloth and cluster deformer.  When a flap crosses the other one a little, it gives a destructive effect (which is not what I want). Even if this effect can be eliminated, I am still bothered by the cloth effect generated by nCloth.   Paper is a rigid body although it can be easily folded (or bended) and it seems that nCloth is not a proper tool to simulate paper folding.  Since I am new to nCloth, there might be a setting to change this: (1) can the destructive effect be eliminated? (2) I tried differnt nClothShape preset but it didn't work. Is there a way to make nCloth shape rigid like a paper?

Or should I wait until the following feature be implimented on Maya?

When we construct a model of origami (a model of a folded sheet of paper) in a computer, it is usual to represent the model as a set of polygons having zero thickness. One of the typical characteristics of origami is that there are many instances where multiple faces are located on a same plane. In these cases, the usual z-buffer rendering method fails as multiple faces have the same depth. Furthermore, many penetrations between faces located close to each other frequently occur when the origami is folded almost flat. However, it is difficult to remove all such penetrations with moving or fixing the geometry of the model. In this paper, we propose a new rendering method that solves these problems one at a time by using the OR matrix. This is a matrix constructed from a crease pattern, and it represents the overlapping relation between every two faces.

http://mitani.cs.tsukuba.ac.jp/paper/origami_rendering2009.pdf