# Vec3

> Talos next · Since 0.6

`[x, y, z]` in metres, Y up, right-handed, forward is -Z.

## Signature

```ts
export type Vec3 = [number, number, number]
```

Import: `import type { Vec3 } from "@argus/api"`

## Example

The tested fixture `fixtures/host/hover.ts`.

```ts
import type { Behavior, Ctx, Vec3 } from "@argus/api"
// docs/API.md, "Forces, torques and impulses": a body that hovers (thrust = m·g), and the same lift
// as four rotors in the airframe's own frame plus a yaw torque. Typechecked by packages/api's tests.
const HUBS: Vec3[] = [[0.3, 0, 0.3], [-0.3, 0, 0.3], [0.3, 0, -0.3], [-0.3, 0, -0.3]]

function hover(ctx: Ctx) {
  const body = ctx.body
  if (!body) return
  if (ctx.props["rotors"] !== true) {
    body.addForce([0, body.mass * 9.81, 0])
    return
  }
  for (const h of HUBS) body.addForceAtPoint([0, (body.mass * 9.81) / 4, 0], h, "local")
  body.addTorque([0, (ctx.props["yaw"] as number | undefined) ?? 0, 0], "local")
}

export default {
  // The first physics step runs before the first update; this is its thrust.
  init(ctx) { hover(ctx) },
  update(ctx) { hover(ctx) },
} satisfies Behavior
```