 uniform vec3 textureAtlasSize;
 uniform vec3 sampleDistance;
 uniform float alphaThresholdForDepth = 0.1;
+uniform float depthCutOff = 0.0;
 
 uniform sampler3D volumeSampler;
 

      ++age;
  }

  for (--age; age < maxAge; age++)  // all fragments
  {
    currentFragment = nextFragment;

  if (maxAge == 0)
    discard;  // no fragment, early exit

  vec4 farPlane = vec4(0, 0, 1, depthCutOff);

  int activeObjects = 0;
  FragmentData currentFragment;
  FragmentData nextFragment;
