text: //This file is automatically rebuilt by the Cesium build process.
  /*global define*/
  define(function() {
      'use strict';
      return "uniform sampler2D u_texture;\n\
  \n\
  uniform float u_avgLuminance;\n\
  uniform float u_threshold;\n\
  uniform float u_offset;\n\
  \n\
  varying vec2 v_textureCoordinates;\n\
  \n\
  float key(float avg)\n\
  {\n\
      float guess = 1.5 - (1.5 / (avg * 0.1 + 1.0));\n\
      return max(0.0, guess) + 0.1;\n\
  }\n\
  \n\
  // See section 9. \"The bright-pass filter\" of Realtime HDR Rendering\n\
  // http://www.cg.tuwien.ac.at/research/publications/2007/Luksch_2007_RHR/Luksch_2007_RHR-RealtimeHDR%20.pdf\n\
  \n\
  void main()\n\
  {\n\
      vec4 color = texture2D(u_texture, v_textureCoordinates);\n\
      vec3 xyz = czm_RGBToXYZ(color.rgb);\n\
      float luminance = xyz.r;\n\
      \n\
      float scaledLum = key(u_avgLuminance) * luminance / u_avgLuminance;\n\
      float brightLum = max(scaledLum - u_threshold, 0.0);\n\
      float brightness = brightLum / (u_offset + brightLum);\n\
      \n\
      xyz.r = brightness;\n\
      gl_FragColor = vec4(czm_XYZToRGB(xyz), 1.0);\n\
  }\n\
  ";
  });