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+--- Thread: Help Cloth backside collision with box (/thread-4580.html)
Cloth backside collision with box - Qriva0 - 17-12-2025
Hi, I have quite simple question - I have simple piece of cloth with surface collsions (actually does not matter, both modes give me the same result) and there is simple rigidbody box collider.
This collider slowly comes from the back of the cloth, and it should collide with it, but it does not. Is that expected result?
I want to note that in general those objects can collide with each other and it works, but currently the box need to pass nearly half of it's size to create reaction from back.
Also other actors are capable of collision from two sides, for example rod, so I assumed it's the case for all objects, but it's not.
Is it possible for cloth to collide with both sides?
RE: Cloth backside collision with box - josemendez - 17-12-2025
(17-12-2025, 11:03 AM)Qriva0 Wrote: Hi, I have quite simple question - I have simple piece of cloth with surface collsions (actually does not matter, both modes give me the same result) and there is simple rigidbody box collider.
This collider slowly comes from the back of the cloth, and it should collide with it, but it does not. Is that expected result?
I want to note that in general those objects can collide with each other and it works, but currently the box need to pass nearly half of it's size to create reaction from back.
Also other actors are capable of collision from two sides, for example rod, so I assumed it's the case for all objects, but it's not.
Is it possible for cloth to collide with both sides?
Hi,
Cloth should by default collide from both sides, in fact there's nothing in the engine that allows to filter collisions by side: particles are spherical and are only defined by a position and radius (no rotation) so they have no concept of "side".
Would it be possible for you to share a scene that exhibits this issue so that I may take a closer look at what's happening?
kind regards
RE: Cloth backside collision with box - Qriva0 - 17-12-2025
(17-12-2025, 11:22 AM)josemendez Wrote: Hi,
Cloth should by default collide from both sides, in fact there's nothing in the engine that allows to filter collisions by side: particles are spherical and are only defined by a position and radius (no rotation) so they have no concept of "side".
Would it be possible for you to share a scene that exhibits this issue so that I may take a closer look at what's happening?
kind regards
Oh so it's not expected. In this case I will try to make additional test and create demo scene for you, in case problem is still there.
Have a great day!
RE: Cloth backside collision with box - Qriva0 - 17-12-2025
Actually I was able to find what was the problem.
I disabled collider. Not obi collider, but unity box collider.
I am not sure if this is just natural side effect, or some kind of bug, but the result is that collision still works, but not 100% properly.
RE: Cloth backside collision with box - josemendez - 18-12-2025
(17-12-2025, 02:52 PM)Qriva0 Wrote: Actually I was able to find what was the problem.
I disabled collider. Not obi collider, but unity box collider.
I am not sure if this is just natural side effect, or some kind of bug, but the result is that collision still works, but not 100% properly.
ObiCollider is just a wrapper that exposes unity collider data to Obi. If you disable the box collider, the ObiCollider should also stop working. Maybe you had another collider inside/behind the box?
RE: Cloth backside collision with box - Qriva0 - 18-12-2025
I don't have other colliders in that place, maybe it's related in some way to rigidbodies, but as you can see something happens here (video expires in 2 days).
https://streamable.com/yqvka8
[attachment=2489]
RE: Cloth backside collision with box - josemendez - 19-12-2025
(18-12-2025, 04:36 PM)Qriva0 Wrote: I don't have other colliders in that place, maybe it's related in some way to rigidbodies, but as you can see something happens here (video expires in 2 days).
https://streamable.com/yqvka8
That's strange indeed, if there's no other colliders then the box should not react to the cloth at all. I've been unable to reproduce this so far, if it becomes an issue would it be possible for you to share a small example/scene/project that exhibits this?
kind regards,
RE: Cloth backside collision with box - Qriva0 - 19-12-2025
(19-12-2025, 09:19 AM)josemendez Wrote: That's strange indeed, if there's no other colliders then the box should not react to the cloth at all. I've been unable to reproduce this so far, if it becomes an issue would it be possible for you to share a small example/scene/project that exhibits this?
kind regards,
I think it's not an issue for me (at least so far), but it's interesting strange case, maybe there is something wrong in my setup. I am going to prepare demo scene in a free moment.
Thank you for taking a look!