24-02-2022, 08:38 AM
(This post was last modified: 24-02-2022, 08:50 AM by josemendez.)
Hi Bill,
It's the first time I see this kind of behavior. Constraining orientation shouldn't cause any issue, see for instance the spring rod sample scene which uses an attachment with constrained orientation. It's also weird that the rod doesn't react in any way to the rigidbody weight when you disable the constrain orientation checkbox. Only the connector seems to move at all. Would it be possible for me to take a look at the scene? You can share a minimal example to support(at)virtualmethodstudio.com
I also tried to reproduce this in a scene of my own to no avail, no matter how much I torture the rod the simulation stays stable. All parameters left to their default values, except for the amount of substeps (cranked up from 4 to 10, since with the default 4 the rod was too flabby to hold the weight of the box):
I did spot kinks in your rod, not sure if these might be desired but quite probably they aren't:
![[Image: mFdA470.png]](https://i.imgur.com/mFdA470.png)
This happens when the orientation along the rod changes sign, and is usually caused by improper orientation vectors in the rod. These vectors determine twist along the rod, you can adjust them in the path editor: http://obi.virtualmethodstudio.com/manua...setup.html
Example of proper orientation vectors:
![[Image: gOv6YbN.png]](https://i.imgur.com/gOv6YbN.png)
Example of improper orientation vectors (can immediately be identified: a 360ยบ kink appears as the rod performs a full revolution around its longitudinal axis):
![[Image: lvf5l1R.png]](https://i.imgur.com/lvf5l1R.png)
It's the first time I see this kind of behavior. Constraining orientation shouldn't cause any issue, see for instance the spring rod sample scene which uses an attachment with constrained orientation. It's also weird that the rod doesn't react in any way to the rigidbody weight when you disable the constrain orientation checkbox. Only the connector seems to move at all. Would it be possible for me to take a look at the scene? You can share a minimal example to support(at)virtualmethodstudio.com
I also tried to reproduce this in a scene of my own to no avail, no matter how much I torture the rod the simulation stays stable. All parameters left to their default values, except for the amount of substeps (cranked up from 4 to 10, since with the default 4 the rod was too flabby to hold the weight of the box):
I did spot kinks in your rod, not sure if these might be desired but quite probably they aren't:
This happens when the orientation along the rod changes sign, and is usually caused by improper orientation vectors in the rod. These vectors determine twist along the rod, you can adjust them in the path editor: http://obi.virtualmethodstudio.com/manua...setup.html
Quote:Orientation tool (rods only):
This tool allows you to define the orientation of each control point. This lets you specify the rest twist of the rod.
Example of proper orientation vectors:
Example of improper orientation vectors (can immediately be identified: a 360ยบ kink appears as the rod performs a full revolution around its longitudinal axis):