<!-- SOLUV · part 204 -->
k toward the light source for
 * safety materials like road markings and reflective tape.
 * - Sheen: Can be used for representing cloth and fabric materials.
 *
 * As a result of these complex shading features, `MeshPhysicalMaterial` has a
 * higher performance cost, per pixel, than other three.js materials. Most
 * effects are disabled by default, and add cost as they are enabled. For
 * best results, always specify an environment map when using this material.
 *
 * @augments MeshStandardMaterial
 * @demo scenes/material-browser.html#MeshPhysicalMaterial
 */
class MeshPhysicalMaterial extends MeshStandardMaterial {

	/**
	 * Constructs a new mesh physical material.
	 *
	 * @param {Object} [parameters] - An object with one or more properties
	 * defining the material's appearance. Any property of the material
	 * (including any property from inherited materials) can be passed
	 * in here. Color values can be passed any type of value accepted
	 * by {@link Color#set}.
	 */
	constructor( parameters ) {

		super();

		/**
		 * This flag can be used for type testing.
		 *
		 * @type {boolean}
		 * @readonly
		 * @default true
		 */
		this.isMeshPhysicalMaterial = true;

		this.defines = {

			'STANDARD': '',
			'PHYSICAL': ''

		};

		this.type = 'MeshPhysicalMaterial';

		/**
		 * The rotation of the anisotropy in tangent, bitangent space, measured in radians
		 * counter-clockwise from the tangent. When `anisotropyMap` is present, this
		 * property provides additional rotation to the vectors in the texture.
		 *
		 * @type {number}
		 * @default 1
		 */
		this.anisotropyRotation = 0;

		/**
		 * Red and green channels represent the anisotropy direction in `[-1, 1]` tangent,
		 * bitangent space, to be rotated by `anisotropyRotation`. The blue channel
		 * contains strength as `[0, 1]` to be multiplied by `anisotropy`.
		 *
		 * `anisotropyMap` represents non-color data. Any texture assigned must have
		 * `texture.colorSpace = NoColorSpace` (default).
		 *
		 * @type {?Texture}
		 * @default null
		 */
		this.anisotropyMap = null;

		/**
		 * The red channel of this texture is multiplied against `clearcoat`,
		 * for per-pixel control over a coating's intensity.
		 *
		 * `clearcoatMap` represents non-color data. Any texture assigned must have
		 * `texture.colorSpace = NoColorSpace` (default).
		 *
		 * @type {?Texture}
		 * @default null
		 */
		this.clearcoatMap = null;

		/**
		 * Roughness of the clear coat layer, from `0.0` to `1.0`.
		 *
		 * @type {number}
		 * @default 0
		 */
		this.clearcoatRoughness = 0.0;

		/**
		 * The green channel of this texture is multiplied against
		 * `clearcoatRoughness`, for per-pixel control over a coating's roughness.
		 *
		 * `clearcoatRoughnessMap` represents non-color data. Any texture assigned must have
		 * `texture.colorSpace = NoColorSpace` (default).
		 *
		 * @type {?Texture}
		 * @default null
		 */
		this.clearcoatRoughnessMap = null;

		/**
		 * How much `clearcoatNormalMap` affects the clear coat layer, from
		 * `(0,0)` to `(1,1)`.
		 *
		 * @type {Vector2}
		 * @default (1,1)
		 */
		this.clearcoatNormalScale = new Vector2( 1, 1 );

		/**
		 * Can be used to enable independent normals for the clear coat layer.
		 *
		 * `clearcoatNormalMap` represents non-color data. Any texture assigned must have
		 * `texture.colorSpace = NoColorSpace` (default).
		 *
		 * @type {?Texture}
		 * @default null
		 */
		this.clearcoatNormalMap = null;

		/**
		 * Index-of-refraction for non-metallic materials, from `1.0` to `2.333`.
		 *
		 * @type {number}
		 * @default 1.5
		 */
		this.ior = 1.5;

		/**
		 * Degree of reflectivity, from `0.0` to `1.0`. Default is `0.5`, which
		 * corresponds to an index-of-refraction of `1.5`.
		 *
		 * This models the reflectivity of non-metallic materials. It has no effect
		 * when `metalness` is `1.0`
		 *
		 * @name MeshPhysicalMaterial#reflectivity
		 * @type {number}
		 * @default 0.5
		 */
		Object.defineProperty( this, 'reflectivity', {
			get: function () {

				return ( clamp( 2.5 * ( this.ior - 1 ) / ( this.ior + 1 ), 0, 1 ) );

			},
			set: function ( reflectivity ) {

				this.ior = ( 1 + 0.4 * reflectivity ) / ( 1 - 0.4 * reflectivity );

			}
		} );

		/**
		 * The red channel of this texture is multiplied against `iridescence`, for per-pixel
		 * control over iridescence.
		 *
		 * `iridescenceMap` represents non-color data. Any texture assigned must have
		 * `texture.colorSpace = NoColorSpace` (default).
		 *
		 * @type {?Texture}
		 * @default null
		 */
		this.iridescenceMap = null;

		/**
		 * Strength of the iridescence RGB color shift effect, represented by an index-of-refraction.
		 * Between `1.0` to `2.333`.
		 *
		 * @type {number}
		 * @default 1.3
		 */
		this.iridescenceIOR = 1.3;

		/**
		 *Array of exactly 2 elements, specifying minimum and maximum thickness of the iridescence layer.
		 Thickness of iridescence layer has an equivalent effect of the one `thickness` has on