# WaterSample

> Talos next · Since 0.7

The water at one point, as {@link WaterHandle.sample} reads it.

## Signature

```ts
export interface WaterSample {
  /** World y of the surface, metres. */
  readonly height: number
  /** Unit surface normal, `[x, y, z]` (y up). */
  readonly normal: Vec3
  /** Velocity of the surface water, `[x, y, z]` m/s: the wave's orbital motion, or a river's flow. */
  readonly velocity: Vec3
  /** Which water holds the point: `"sea"`, `"lake"` or `"river"`. */
  readonly kind: WaterKind
}
```

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

## Members

| Member | Signature | Description |
|---|---|---|
| `height` | `readonly height: number` | World y of the surface, metres. |
| `normal` | `readonly normal: Vec3` | Unit surface normal, `[x, y, z]` (y up). |
| `velocity` | `readonly velocity: Vec3` | Velocity of the surface water, `[x, y, z]` m/s: the wave's orbital motion, or a river's flow. |
| `kind` | `readonly kind: WaterKind` | Which water holds the point: `"sea"`, `"lake"` or `"river"`. |

## Example

The tested fixture `fixtures/recipes/jump-pad-and-elevator/scenes/behaviors/jump-pad.ts`.

```ts
import type { Behavior, Vec3 } from "@argus/api"

/**
 * A trigger volume that launches whatever walks onto it.
 *
 * The pad does not reach into the other entity: it says who entered and how hard to launch them,
 * and the character's own behaviour calls `ctx.controller.setVelocity`. So one pad works for the
 * player, an NPC or a crate with a controller, and a character that should not be launched simply
 * ignores the event. The same shape is a knockback volume, a geyser or a car's booster strip.
 */
interface Props {
  /** The velocity to give, m/s. Straight up by default. */
  velocity?: Vec3
}

export default {
  onTrigger(ctx, trigger) {
    if (!trigger.entering) return
    ctx.events.emit("launch", { target: trigger.other.id, velocity: ctx.props.velocity ?? [0, 9, 0] })
  },
} satisfies Behavior<Record<string, never>, Props>
```