gistfile1.txt

float depthValueFromSample( vec2 depthPos){
  vec2  halfvec = vec2(.5,.5);
  vec3 hsl = rgb2hsl( texture2DRect(texture, floor(depthPos) + halfvec ).xyz );
  float depth = hsl.r;
	if(hsl.b > .2){
		return depth * ( maxDepth - minDepth ) + minDepth;
	}
	else {
		return 0.0;
	}
}