> For the complete documentation index, see [llms.txt](https://stoneforgeteam.gitbook.io/stoneforgeteam-docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://stoneforgeteam.gitbook.io/stoneforgeteam-docs/content/fx.md).

# Visual effects

`Fx.Play` plays an animation on a unit, following it, as the game's own effect animations do. Use one of the game's sprites, or a strip of your own:

```csharp
// The game's electric weapon hit, at chest height, glowing blue.
Fx.Play(attack.Target, Sprite.s_weapondamage_electricity, new FxOptions
{
    OffsetY = -14,
    Light = Draw.Rgb(110, 170, 255),
});

// A mod's own: a PNG in Assets, its frames side by side.
int spark = context.LoadSprite("spark.png", frames: 6);
Visual? aura = Fx.Play(player, spark, new FxOptions { Loop = true, Under = true });
// later
aura?.Stop();
```

`Play` returns a `Visual` (`Playing`, `Stop()`, `Instance`), or `null` if there's no such unit.

| `FxOptions`          |                                                                     |
| -------------------- | ------------------------------------------------------------------- |
| `Speed`              | Frames per game frame (the game's effects mostly play at 0.5).      |
| `Loop`               | Plays until stopped (an aura) instead of once.                      |
| `OffsetX`, `OffsetY` | From where the unit is drawn (its feet): -16 is about chest height. |
| `Colour`, `Alpha`    | Its tint (`Draw.Rgb`) and opacity.                                  |
| `Under`              | Drawn behind the unit: a glow on the ground at its feet.            |
| `Light`              | The colour of the light it casts (default: the game's warm orange). |

For an animation that lasts as long as a buff, use the buff's `SetAura` (see [Buffs](/stoneforgeteam-docs/content/buffs.md)).


---

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