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+--- Thread: question about acceptable meshes (tearable) (/thread-3538.html)
question about acceptable meshes (tearable) - danazoid - 26-07-2022
Hi, I was testing out tearable cloth today and got the error "ArgumentOutOfRangeException: Index was out of range. Must be non-negative and less than the size of the collection."
I did some testing and this is what I got
1) "thick" mesh (my custom mesh that is 2 vertices thick): error
2) plane mesh (and my custom mesh reduced to 1 vertex in thickness): no error
3) simple cube mesh (in-built unity version, vertices 2 x 2 x 2): no error
4) "thick" plane mesh (essentially a simple cuboid with vertices 4 x 4 x 2): error
It seems to me the error occurs when the cloth is "thick" (ie not just 1 vertex in thickness). I don't know about the cube.
I would like to confirm if Obi Cloth is only designed to handle flat, 1 vertex thick meshes.
I want to be able to cut/tear cloths with a thickness to them, do any of your solutions allow that? (eg softbody)
Thanks in advance.
RE: question about acceptable meshes (tearable) - josemendez - 26-07-2022
(26-07-2022, 01:43 PM)danazoid Wrote: Hi, I was testing out tearable cloth today and got the error "ArgumentOutOfRangeException: Index was out of range. Must be non-negative and less than the size of the collection."
I did some testing and this is what I got
1) "thick" mesh (my custom mesh that is 2 vertices thick): error
2) plane mesh (and my custom mesh reduced to 1 vertex in thickness): no error
3) simple cube mesh (in-built unity version, vertices 2 x 2 x 2): no error
4) "thick" plane mesh (essentially a simple cuboid with vertices 4 x 4 x 2): error
It seems to me the error occurs when the cloth is "thick" (ie not just 1 vertex in thickness). I don't know about the cube.
I would like to confirm if Obi Cloth is only designed to handle flat, 1 vertex thick meshes.
I want to be able to cut/tear cloths with a thickness to them, do any of your solutions allow that? (eg softbody)
Thanks in advance.
Hi Danazoid,
The limitation for cloth meshes is that they cannot be non-manifold: http://obi.virtualmethodstudio.com/manual/6.3/clothsetup.htmlanifold, as stated in the manual:
If you're not sure what "non-manifold"means, see:
https://sinestesia.co/blog/tutorials/non-manifold-meshes-and-how-to-fix-them/
https://www.sculpteo.com/en/3d-learning-hub/create-3d-file/fix-non-manifold-geometry/
Quote:I would like to confirm if Obi Cloth is only designed to handle flat, 1 vertex thick meshes.
Not sure what you mean exactly by "1-vertex" thick, but non-manifold meshes can be "glued" to a 2-manifold mesh using proxies:http://obi.virtualmethodstudio.com/manual/6.3/clothproxies.html
This does not work for tearable cloth, though. By definition, tearable cloth must be 2-manifold (which is believe is what you mean by 1-vertex thick).
Quote:I want to be able to cut/tear cloths with a thickness to them, do any of your solutions allow that? (eg softbody)
Nope, this is extremely costly to do. The reason is that when you cut a surface, you need to update both its physical representation (in Obi, particles + constraints) as well as its visual representation (triangle mesh). For a volumetric shape to be cut, it must be made of tetrahedrons, which are the volumetric equivalent of triangles.
Your best bet to do what you need is find a tetrahedral FEM (finite-element method) engine. To the best of my knowledge, no existing games do this, and there are no implementations of this in the Asset Store.
kind regards,
RE: question about acceptable meshes (tearable) - danazoid - 27-07-2022
(26-07-2022, 01:53 PM)josemendez Wrote: This does not work for tearable cloth, though. By definition, tearable cloth must be 2-manifold (which is believe is what you mean by 1-vertex thick).
Thanks for the fast reply!
Can I just check: do you mean that I cannot use the cloth proxy with a tearable cloth?
RE: question about acceptable meshes (tearable) - josemendez - 27-07-2022
(27-07-2022, 07:06 AM)danazoid Wrote: Can I just check: do you mean that I cannot use the cloth proxy with a tearable cloth?
Yes, that's what I meant: proxies work by skinning an arbitrary mesh to a simulated cloth. Skinning cannot work if the cloth modifies its topology (ie, tears).