# Ray

> Talos 0.7 · Since 0.7

A world ray: `dir` is unit length.

## Signature

```ts
export interface Ray {
  /** Where the ray starts: on the view's near plane, world space. */
  readonly origin: Vec3
  /** Which way it goes: a unit vector, world space. */
  readonly dir: Vec3
}
```

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

## Members

| Member | Signature | Description |
|---|---|---|
| `origin` | `readonly origin: Vec3` | Where the ray starts: on the view's near plane, world space. |
| `dir` | `readonly dir: Vec3` | Which way it goes: a unit vector, world space. |

## Example

The tested fixture `fixtures/app/agent.ts`.

```ts
import type { Behavior } from "@argus/api"

// Sends a nav agent to `props.target` once, then reports arrival through ctx.state so the
// test can read it without polling the crowd directly.
export default {
  init(ctx) {
    ctx.state.arrived = false
    ctx.nav?.goTo(ctx.props.target as [number, number, number])
  },
  update(ctx) {
    if (ctx.nav?.arrived) ctx.state.arrived = true
  },
} satisfies Behavior
```