code: function MeshPhysicalMaterial( parameters ) {
  
  	MeshStandardMaterial.call( this );
  
  	this.defines = { 'PHYSICAL': '' };
  
  	this.type = 'MeshPhysicalMaterial';
  
  	this.reflectivity = 0.5; // maps to F0 = 0.04
  
  	this.clearCoat = 0.0;
  	this.clearCoatRoughness = 0.0;
  
  	this.setValues( parameters );
  
  }
docs: @author WestLangley / http://github.com/WestLangley
  
  parameters = {
  reflectivity: <float>
  }