# `MaterialSpec.transmission`

> Contract 2.0.0 · package sha256 `a857eca95b35921109faf997094bb4192f12527d9d0fcd4be7e97f06425bad6e` · generated from `configurator-runtime.d.ts` by `services/onsite-scripter/scripts/build-contract-docs.mjs`; edit the source, not this file.

Property of [`MaterialSpec`](MaterialSpec.md) · inherited by [`MaterialInput`](MaterialInput.md) · stable · since 2.0.0

```ts
transmission?: {
  factor?: number;
  thickness?: number;
  attenuationColor?: ColorValue;
  attenuationDistance?: number;
};
```

KHR_materials_transmission and volume. The runtime draws what a transmissive part shows through it at half the drawing buffer's resolution or less, on every tier (spec Appendix B.4, X17); apps write no transmission setting. A transmissive part, like a 'blend' one, casts a solid shadow unless its `shadows.cast` is false.

**Default:** { factor: 0 }

## Fields

<a id="factor"></a>
### `factor`

```ts
factor?: number;
```

0..1; 0 is opaque to light.

**Default:** 0

<a id="thickness"></a>
### `thickness`

```ts
thickness?: number;
```

Metres of volume, for refraction.

**Default:** 0 (thin-walled)

<a id="attenuationcolor"></a>
### `attenuationColor`

```ts
attenuationColor?: ColorValue;
```

The colour light takes on at `attenuationDistance`.

**Default:** '#ffffff'

<a id="attenuationdistance"></a>
### `attenuationDistance`

```ts
attenuationDistance?: number;
```

Metres, finite: Infinity is invalid input, since look state is canonical JSON (spec section 3.4). To turn a GLB's or an earlier write's attenuation off, write `attenuationColor: '#ffffff'`: white absorbs nothing (KHR_materials_volume).

**Default:** unset, no attenuation (glTF's Infinity)

## Generic-API test (spec 3.1)

| Rule | Result |
| --- | --- |
| 1. Neutral name | pass: `transmission` names no product |
| 2. A precedent | pass (through its owner [`MaterialSpec`](MaterialSpec.md)): [glTF 2.0 metallic-roughness material](https://registry.khronos.org/glTF/specs/2.0/glTF-2.0.html#metallic-roughness-material) (row `K10`); [glTF KHR_materials_sheen](https://github.com/KhronosGroup/glTF/tree/main/extensions/2.0/Khronos/KHR_materials_sheen) (row `K10`); [glTF KHR_materials_transmission](https://github.com/KhronosGroup/glTF/tree/main/extensions/2.0/Khronos/KHR_materials_transmission) (row `K10`); [glTF KHR_materials_unlit](https://github.com/KhronosGroup/glTF/tree/main/extensions/2.0/Khronos/KHR_materials_unlit) (row `K10`) |
| 3. Two apps, or labs | pass: 28 apps (ledger: app-04c2774145, app-0c773a4ee3, app-37356bf09f, app-378d190f1b, app-4762caacdc, app-4f16d2f6da, app-4fd23bc869, app-510d750508 and 20 more; fleet cross-check: app-fc07850558) |
| 4. The cheaper fix first | decided per need in Appendix B: rows `K10` (through its owner [`MaterialSpec`](MaterialSpec.md)) at tier stable (a member only where no rule, data, asset or app code serves the need) |