setupVariants() {

		// METALNESS

		const metalnessNode = this.metalnessNode ? float( this.metalnessNode ) : materialMetalness;

		metalness.assign( metalnessNode );

		// ROUGHNESS

		let roughnessNode = this.roughnessNode ? float( this.roughnessNode ) : materialRoughness;
		roughnessNode = getRoughness( { roughness: roughnessNode } );

		roughness.assign( roughnessNode );

		// SPECULAR COLOR

		this.setupSpecular();

		// DIFFUSE COLOR

		diffuseColor.assign( vec4( diffuseColor.rgb.mul( metalnessNode.oneMinus() ), diffuseColor.a ) );

	}
Setups the standard specific node variables.

@param {NodeBuilder} builder - The current node builder.