# SpringChain

> Talos 0.7 · Since 0.7

One chain of bones swung by springs.

## Fields

| Field | Type | Required | Default | Allowed values | Description |
|---|---|---|---|---|---|
| `name` | `string` | no | `chain<N>` |  | A label for messages. Default `chain<N>`, N the chain's place in the list. |
| `root` | `string` | no |  |  | The first bone of the chain, by the rig's own name. With `tip`, the chain is the path from `root` down to `tip`; alone, a chain of one bone. Give `root` (with or without `tip`) or `joints`, not both. |
| `tip` | `string` | no |  |  | The last bone of the chain: a descendant of `root`. |
| `joints` | `string[]` | no |  |  | The bones of the chain, root first, each the child of the one before. The other way to say `root` and `tip`. |
| `stiffness` | `number` | no | `40` |  | Pull back towards the animated pose, 0 to 100000, in 1/s². 0 is a limp rope, about 40 a ponytail, about 200 stiff. Default 40. |
| `damping` | `number` | no | `2` |  | Speed lost per second, 0 to 1000. 0 swings for ever; about 2 settles in a second or two. Default 2. |
| `gravity` | `Vec3` | no | `[0,-9.81,0]` |  | Acceleration in world space, m/s². Default [0, -9.81, 0]. Each number is finite. |
| `radius` | `number` | no | `0` |  | Collision radius of the chain's tail points, metres, 0 to 10. Default 0. |
| `tail` | `Vec3` | no | `[0` |  | Where the end of the last bone is, in that bone's own space. Default [0, 0, 0]: the last bone is extended by its own length. |

## See also

- `Vec3`