three.js/examples/jsm/nodes/functions/BSDF/BRDF_Lambert.js

import { tslFn } from '../../shadernode/ShaderNode.js';

const BRDF_Lambert = tslFn( ( inputs ) => {

	return inputs.diffuseColor.mul( 1 / Math.PI ); // punctual light

} ); // validated

export default BRDF_Lambert;