lightspeed.johnny

I am close to thinking Javascript is indeed usable for realtime data manipulation/creation within Max/MSP, however I found a hurdle which I am having difficulty crossing:

I have a jacascript task (running at 30 iterations per sec) which creates an array of 500 objects - currently the object is simply an array of 3 values - which loos like [x, y, rgb]. So basically it is an array of 500 points.

I am trying to find the most efficient way of sending this array of points to a Max external at a rate of 30 frames/sec or so. I was hoping this could be done with dicts - as dicts are much easier to work with in externals than jitter matrices. Also, I don't need to do any processing using jitter - I just need to pass around an array of 500 points. It may not be possible with javascript and dicts - I may indeed end up having to do everything with matrices and Max expr objects - but it sure would be nice to keep everything in javascript.

Note that creating this array and displaying the points is no problem - however, getting it into a dict that I can pass to my external is proving to be difficult. Hopefully some of the smart people here can provide some suggestions.

In short, here is what I am trying to achieve:

need-help-with-strategy-for-passing-around-array-of-approx-500-objects

I'm not completely sure I understand but if you already have a Dict in JS just make a Dict in Max with the same exact name and they will be in sync.

I’m not completely sure I understand but if you already have a Dict in JS just make a Dict in Max with the same exact name and they will be in sync.

The part that I am trying to figure out is how to properly 

Quite simply, here is my Max Dict object created in Javascript (and accessible in Max)

var myDict = new Dict("myDict");
myDict.parse('{ "points":[]}');


So now myDict is a dict with a single key called "points". And that key contains an object which is an array - which I have initialized to be empty.

What I am trying to figure out is how to populate that array with objects - and those objects are also arrays.

for (var i = 0; i < numPoints; i++) {
   var pt = [x,y,rgb]; // create an array of 3 values

   // HOW DO I APPEND pt to the myDict.points array?

   // in JS you do this: myJSObj.points.push(pt);
}


 After a night of performance testing with Dict... I have all but abandoned the idea of using Dicts for real-time data processing.... so it looks like my Max external will have to be a jitter object afterall instead of a just a normal Max object.

Kinda sucks, because I am actually not doing any jitter (matrix) processing of the data (at the moment) - but now that I am starting down that path, I might be able to do just about everything I want to do with jit.expr instead of javascript. Much harder to debug - but seems much more efficient.

The part that I am trying to figure out is how to properly populate the Max Dict object in javascript.

Edit: After a night of performance testing with Dict... I have all but abandoned the idea of using Dicts for real-time data processing.... so it looks like my Max external will have to be a jitter object afterall instead of a just a normal Max object.

Kinda sucks, because I am actually not doing any jitter (matrix) processing of the data (at the moment) - but now that I am starting down that path, I might be able to do just about everything I want to do with jit.expr instead of javascript. Much harder to debug - but seems much more efficient.


the way I see it you *are* doing matrix processing - x, y, rgb. That's a 3-plane jitter matrix.

var myDict = new Dict('myDict');
var points = new Dict('points');

var x = 100;
var y = 100;
var rgb = 100;
var numPoints = 5;

for (var i = 0; i < numPoints; i++) {
   var pt = [x+i,y+i,rgb+i]; 
   points.replace('point-'+i, pt);
}

myDict.replace('points', points);


This would make your Max Dict look like this

{
    "points" :     {
        "point-0" : [ 100, 100, 100 ],
        "point-1" : [ 101, 101, 101 ],
        "point-2" : [ 102, 102, 102 ],
        "point-3" : [ 103, 103, 103 ],
        "point-4" : [ 104, 104, 104 ]
    }

}


You should check out the dict_test.js in the Dict helpfile.

I don't think this would work because according to the javascript spec, a map is not an ordered list - so there is no guarantee that the points will be stored in the map in an ordered fashion. For an ordered list, you need to use an array.

I can't be certain of a guarantee but I just tried this and it comes up correct every time. It is just reading from the pt array in sequential order.

var myDict = new Dict('myDict');
var points = new Dict('points');

var x = 100;
var y = 100;
var rgb = 100;
var numPoints = 1000;

for (var i = 0; i < numPoints; i++) {
   var pt = ['x'+i,'y'+i,'rgb'+i]; 
   points.replace('point-'+i, pt);
}

myDict.replace('points', points);



I can't be certain of a guarantee but I just tried this and it comes up correct every time. It is just reading from the pt array in sequential order. 

the way I see it you *are* doing matrix processing – x, y, rgb. That’s a 3-plane jitter matrix.

I agree... it is becoming more and more obvious. I think I am just going to bite-the-bullet and turn my external into a jitter external.

What I meant to imply, is that it is not using jitter the way jitter is typically used - i.e., as a matrix of raster points representing raster data. My data is a list of discrete points - representing vector data.

I can’t be certain of a guarantee but I just tried this and it comes up correct every time. It is just reading from the pt array in sequential order.

There is still no way to iterate through this map/dict in a guaranteed sequential fashion. It is not possible unless someone from Cycling pops in and says - yes indeed that keys are stored sequentially as added to the map. Even if they are "stored" sequentially, I am not sure there is a guaranteed way of iterating over them in a sequential method.

It is a standard rule of javascript (and every othern modern language) - that maps/dicts are un-ordered lists, and arrays are ordered lists.

Need help with strategy for passing around array of approx 500 objects