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+--- Forum: Obi Rope (https://obi.virtualmethodstudio.com/forum/forum-4.html)
+--- Thread: Help How to fix both ends when using bones for a ObiRope? (/thread-4463.html)
How to fix both ends when using bones for a ObiRope? - kodra - 14-03-2025
As this example in document shows, ObiRope can be fixed on both ends, leaving only the middle part free.
But I can't figure out how to integrate with a character with bone hierarchy. For example, in this example the dragon's tail is made of 12 bones. In this case, how to make only the first (root) and last (tip) bones follow a predefined animation, while let the middle part solved by Obi?
I guess I need to use an attachment, but I'm not sure how to set it up with bones...
RE: How to fix both ends when using bones for a ObiRope? - josemendez - 14-03-2025
(14-03-2025, 10:57 AM)kodra Wrote: As this example in document shows, ObiRope can be fixed on both ends, leaving only the middle part free.
But I can't figure out how to integrate with a character with bone hierarchy. For example, in this example the dragon's tail is made of 12 bones. In this case, how to make only the first (root) and last (tip) bones follow a predefined animation, while let hair_1 and hair_2 be solved by Obi?
Hi!
ObiRope and ObiBone work quite differently.For pre-existing bone hierarchies, you'd typically use ObiBone.
You can use skin constraints to control how simulation/animation are blended along the bone hierarchy. Their skin radius parameter controls the maximum distance each particle can move away from the position specified by the animation before the constraint takes effect.
To have the first and last bones to follow the bone position as specified in the animation, set the skin radius curve to a inverted "U" shape, so that it starts at 0, goes up to 1, then goes back to zero. Also make sure skin compliance is set to 0, so that there's no elasticity to the constraint.
kind regards,
RE: How to fix both ends when using bones for a ObiRope? - josemendez - 14-03-2025
Also note that if you want to use a rope or a rod instead of ObiBone to drive a bone hierarchy, you can do so by copying particle positions to the bone transforms using a custom script.
kind regards,
RE: How to fix both ends when using bones for a ObiRope? - josemendez - 14-03-2025
(14-03-2025, 10:57 AM)kodra Wrote: I guess I need to use an attachment, but I'm not sure how to set it up with bones...
ObiBone isn't really designed to use attachments. In case you wanted to, you can manually create a particle group for the particle(s) you want to attach and then assign it to an attachment as usual. See: https://obi.virtualmethodstudio.com/manual/7.0/scriptingattachments.html
kind regards,
RE: How to fix both ends when using bones for a ObiRope? - kodra - 11-04-2025
(14-03-2025, 11:21 AM)josemendez Wrote: ObiBone isn't really designed to use attachments. In case you wanted to, you can manually create a particle group for the particle(s) you want to attach and then assign it to an attachment as usual. See: https://obi.virtualmethodstudio.com/manual/7.0/scriptingattachments.html
kind regards,
Thank you for the answer!
Just to clarify, when you said "ObiBone isn't really designed to use attachments", you mean there isn't UI to support it, but if I create attachments via script it would work, right?
RE: How to fix both ends when using bones for a ObiRope? - josemendez - 12-04-2025
(11-04-2025, 11:56 PM)kodra Wrote: Thank you for the answer!
Just to clarify, when you said "ObiBone isn't really designed to use attachments", you mean there isn't UI to support it, but if I create attachments via script it would work, right?
Correct, there’s no UI but you can create and use them programmatically.
In upcoming updates (Obi 7.1) we’ve exposed each bone as a particle group, so it’s easy and convenient to use them.