text: //This file is automatically rebuilt by the Cesium build process.
  define(function() {
      'use strict';
      return "uniform sampler2D depthTexture;\n\
  \n\
  varying vec2 v_textureCoordinates;\n\
  \n\
  void main(void)\n\
  {\n\
      float depth = czm_readDepth(depthTexture, v_textureCoordinates);\n\
      gl_FragColor = vec4(vec3(depth), 1.0);\n\
  }\n\
  ";
  });