# `ShadingNodes.base`

> 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.

Method of [`ShadingNodes`](ShadingNodes.md) · labs, `@experimental` · since 2.0.0

```ts
base<K extends 'baseColor' | 'roughness' | 'metallic'>(input: K): ShadingNode<K extends 'baseColor' ? 'color3' : 'float'>;
```

The value the material's base fields feed `gltf_pbr`'s input, the one an omitted [`ShadingOutputs`](ShadingOutputs.md)
key keeps: for 'baseColor', the factor × the slot's map sampled at its placement × the vertex
colour (`COLOR_0`); for 'roughness' and 'metallic', the factor × the map's channel. An output
replaces that input; the maps are not applied to it again. In a `fadeMs` crossfade, two sides
wearing one graph blend these inputs (each sampled at its own placement) and the graph runs on
the blend; sides wearing different graphs, or a graph and none, each run their own and the
results blend.

## Generic-API test (spec 3.1)

| Rule | Result |
| --- | --- |
| 1. Neutral name | pass: `base` names no product |
| 2. A precedent | pass (through its owner [`ShadingNodes`](ShadingNodes.md)): [Babylon.js NodeMaterial](https://github.com/BabylonJS/Babylon.js/blob/master/packages/dev/core/src/Materials/Node/nodeMaterial.ts) (row `K21`); [Blender shader nodes](https://docs.blender.org/manual/en/latest/render/shader_nodes/index.html) (row `K21`) |
| 3. Two apps, or labs | labs (`@experimental` at a stable path, reached through `has()` or `supports()`): it graduates when a second app uses it; apps today: app-510d750508, app-59c5b5751e |
| 4. The cheaper fix first | decided per need in Appendix B: rows `K21` (through its owner [`ShadingNodes`](ShadingNodes.md)) at tier labs (a member only where no rule, data, asset or app code serves the need) |