mandelbrot.js

[ 
    {$limit:1},
    {$set: { x : {$range:[-144,0]}, y : {$range:[-120,0]} }},
    {$unwind :"$x"},
    {$unwind: "$y"},
    {$set : { r: {$add: [{$divide:["$x",8000]},-0.73]}, i: {$add:[{$divide:["$y",8000]},0.15]}}},
    {$set : { c : { $reduce : { input: {$range:[0,300]}, initialValue : { r:0,i:0,it:0 }, in :
    { $cond : { if: { $lt:["$$value.r",4]}, then: { it:{$add:["$$value.it",1]},
         r: {$add:[{$subtract:[{$pow:["$$value.r",2]}, {$pow:["$$value.i",2]} ]},"$r"]},
         i: {$add: [{$multiply:[2,"$$value.r","$$value.i"]},"$i"]}  } ,else: "$$value"}}}}}},
    {$project: { x:1,y:1,intensity:"$c.it"}}
]