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Question about tearing of clothing
#1
Hello!

I'm developing a first aid course where you have to use a defibrillator, and part of the course is that you have to cut up the patients shirt to place the electrodes on their skin.

I've already used Obi Rope for some time, and I've been considering getting Obi Cloth for this use case to simulate the clothes physically instead of just swapping or animating shirt mesh (which is the current planned solution).

However, I'm a little unsure whether it's possible or not. I see that there are some incompatibilities with torn cloth and clothing, as clothing needs a skinned mesh whereas tearing does not support skinned mesh. However, full on dynamic tearing isn't really necessary either. If I could just somehow mark a seam where I can make the cloth split that would be more than enough, somewhat mechanically similar to undoing the buttons on a dress shirt.

Is this possible to achieve with either of the three cloth types? Either through tearable cloth or for regular/skinned cloth some sort of gluing two edges together that can then be "unglued" in real time?
A pertinent detail is that the character is not an animated character, it's a physically simulated ragdoll. In other words, all movement of the character will be handled by the unity physics system. The shirt must either be cloth wrapped around the torso of the character, or simulate parts or all of a shirt mesh that's attached to the character's physically simulated armature.
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#2
(13-04-2023, 03:10 PM)MarsMV Wrote: However, I'm a little unsure whether it's possible or not. I see that there are some incompatibilities with torn cloth and clothing, as clothing needs a skinned mesh whereas tearing does not support skinned mesh. However, full on dynamic tearing isn't really necessary either. If I could just somehow mark a seam where I can make the cloth split that would be more than enough, somewhat mechanically similar to undoing the buttons on a dress shirt.

Hi!

You could use stitch constraints to stitch skinned cloth particles together, as opposed to tearing (splitting one particle in two, which requires updating both the particle representation of the cloth and the mesh topology). You can use the ObiStitcher component, or create the constraints manually.

(13-04-2023, 03:10 PM)MarsMV Wrote: regular/skinned cloth some sort of gluing two edges together that can then be "unglued" in real time?

Yes, this is what stitches do. Basically they introduce a constraint that forces two particles to share the same position. Keep in mind however that this assumes the location where the cloth will be "torn" is predefined, and that you're in charge of determining when the constraints must be removed to "tear" the cloth.

See the included "RuntimeCloth" sample scene for an example that creates two procedural cloth sheets and sews their edges together using stitch constraints to create some sort of sack entirely at runtime.

kind regards,
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#3
Awesome, sounds like exactly what I need! Thank you! Sonrisa
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