seExpr script to make a jerusalem stone texture

gistfile1.txt

$noiseBigU = fbm([$u*8, $v*8,1],6,2,.75);
$u = $u + $noiseBigU*.005;
$noiseBigV = fbm([111+$u*8, 111+$v*8,0],6,2,.75);
$v = $v + $noiseBigV*.0025;

# number of horizontal bands
$vNum = 20;
# variation in width of horizontal bands
$vVar = 0.35;

# horizontal noise
$vNoise = noise($v*$vNum)*2-1;
$vNoise = $vNoise * $vVar;

# v2 is the noisy horizontal grad
$v2 = $v*$vNum+$vNoise;

# give each row an index
$rowIndex = floor($v2);
#give each row a random value
$rowRandom = hash($rowIndex);

#### End of rows 

# min and max number of bricks per row
$uNumMin = 9;
$uNumMax = 12;
$uNum = compress($rowRandom, $uNumMin, $uNumMax);

# 
$uVar = 0.35;
$uNoise = noise($u* $uNum * .5)*2-1;
$uNoise = $uNoise * $uVar;
$u2 = ($u * $uNum + $uNoise) + ($rowIndex) * .5 + ($rowRandom-.5) *.5;
$colIndex = floor($u2);

#### End of cols 

$v2Ramp = fit(abs(fmod($v2,1)*2-1),.4,1,0,1);
$u2Ramp = fit(abs(fmod($u2,1)*2-1),.4,1,0,1);

# normalize grout aspect ratio thickness 
$v2Ramp = fit($v2Ramp,0,1,1-($uNum/$vNum),1);
$grout1 = gaussstep(1-((1-$u2Ramp)*(1-$v2Ramp)),.99,1)*1;
$grout2 = gaussstep(max($u2Ramp, $v2Ramp),.95,1)*1;
$grout = 1-((1-$grout1)*(1-$grout2));

#### End of grout

$brickIndex = ($rowIndex * $uNum) + $colIndex; 
$brickRandom = hash($brickIndex);

$out = $brickRandom * (1-$grout);

$color = [$out,$out,$out];
$color