# TerrainMaterialRule

> Talos 0.6 · Since 0.6

One rule of `material.rules`: a layer to weight, and where.

## Fields

| Field | Type | Required | Default | Allowed values | Description |
|---|---|---|---|---|---|
| `layer` | `string` | yes |  |  | The terrain file's layer this rule paints; it must be declared in `layers`. |
| `where` | `TerrainWhere` | no |  |  | Where the rule applies. Absent: everywhere. |
| `weight` | `number` | no | `1` |  | How strongly the layer is weighted where the rule applies. Default 1. |
| `noiseM` | `number` | no |  |  | Wavelength in metres of a noise that breaks up the rule's edge. Absent: no noise. |

## See also

- `TerrainWhere`