   uvec2 ij = uvec2(pos.xy);
 
   gl_FragDepth = 1.0;
-  position = vec4(-2, -2, 1, POSITION_NOT_SET);
 
   uint maxAge = counters[Saddr(ij)];
 

  float endDistance = dot(world, layerPlanes[layerIndex]);
  while (endDistance < 0)
  {
    setPositionAndDepth(viewMatrix *
                        vec4(world.xyz - endDistance * layerPlanes[layerIndex].xyz, 1.0f));
    setColorForLayer(layerIndex, vec4(0));
    ++layerIndex;
    endDistance = dot(world, layerPlanes[layerIndex]);


uniform sampler3D volumeSampler;

#define transferFunctionRowCount 64.0f

struct VolumeData
