Variance Antialiasing in Gather vex function

[Pazuzu]

Hi!

 

Sorry for the double post but in SESI forums there is not response from anyone  

Has someone an example of how I can get variance antialiasing when import a variable with gather?, for example ray:length. 
 

I've tried do that this way, and it does not work with variance antialiasing but standard sampling from gather :

//compute transmission vector 
$Nf = frontface(N,I); 
fresnel(normalize(I),$Nf,1/$ior,kr,$kt,R,$Tr); 

//temp variables 
float raylength; 
vector surfacecolor; 

//gather loop 
gather(P,$Tr,"samples",$attSamples, 
             "bias",$bias, 
             "maxdist",$maxDistance, 
             "angle",radians(60), 
             "samplebase",1, 
             "variancevar","ray:length", 
             "ray:length",raylength) 
              
{ 
      raylength += 0; 
} 
else 
{ 
      raylength = $densityAttenuation; 
} 


raylength /= max($attSamples,1); 
raylength = fit(raylength,0,$densityAttenuation,1,0); 
$katt = pow(raylength,$attExponent);