three.js/src/materials/MeshDepthMaterial.js

/**
 * @author mr.doob / http://mrdoob.com/
 * @author alteredq / http://alteredqualia.com/
 *
 * parameters = {
 *  opacity: <float>,
 
 *  blending: THREE.NormalBlending,
 *  depthTest: <bool>,
 
 *  wireframe: <boolean>,
 *  wireframeLinewidth: <float>
 * } 
 */

THREE.MeshDepthMaterial = function ( parameters ) {

	THREE.Material.call( this, parameters );

	parameters = parameters || {};

	this.shading = parameters.shading !== undefined ? parameters.shading : THREE.SmoothShading; // doesn't really apply here, normals are not used

	this.wireframe = parameters.wireframe !== undefined ? parameters.wireframe : false;
	this.wireframeLinewidth = parameters.wireframeLinewidth !== undefined ? parameters.wireframeLinewidth : 1;

};

THREE.MeshDepthMaterial.prototype = new THREE.Material();
THREE.MeshDepthMaterial.prototype.constructor = THREE.MeshDepthMaterial;