Any ar js multimarkers learning tutorial? - three.js

Question

I have been searching for ar.js multimarkers tutorial or anything that explains about it. But all I can find is 2 examples, but no tutorials or explanations.
So far, I understand that it requires to learn the pattern or order of the markers, then it stores it in localStorage. This data is used later to display the image.
What I don't understand, is how this "learner" is implemented. Also, the learning process is only used once by the "creator", right? The output file should be stored and then served later when needed, not created from scratch at each person's phone or computer.
Any help is appreciated.

Answer 1

Since the question is mostly about the learner page, I'll try to break it down as much as i can:
1) You need to have an array of {type, URL} objects.
A sample of creating the default array is shown below (source code):
var markersControlsParameters = [
{
type : 'pattern',
patternUrl : 'examples/marker-training/examples/pattern-files/pattern-hiro.patt',
},
{
type : 'pattern',
patternUrl : 'examples/marker-training/examples/pattern-files/pattern-kanji.patt',
}]
2) You need to feed this to the 'learner' object.
By default the above object is being encoded into the url (source) and then decoded by the learner site. What is important, happens on the site:
for each object in the array, an ArMarkerControls object is created and stored:
// array.forEach(function(markerParams){
var markerRoot = new THREE.Group()
scene.add(markerRoot)
// create markerControls for our markerRoot
var markerControls = new THREEx.ArMarkerControls(arToolkitContext, markerRoot, markerParams)
subMarkersControls.push(markerControls)
The subMarkersControls is used to create the object used to do the learning. At long last:
var multiMarkerLearning = new THREEx.ArMultiMakersLearning(arToolkitContext, subMarkersControls)
The example learner site has multiple utility functions, but as far as i know, the most important here are the ArMultiMakersLearning members which can be used in the following order (or any other):
// this method resets previously collected statistics
multiMarkerLearning.resetStats()
// this member flag enables data collection
multiMarkerLearning.enabled = true
// this member flag stops data collection
multiMarkerLearning.enabled = false
// To obtain the 'learned' data, simply call .toJSON()
var jsonString = multiMarkerLearning.toJSON()
Thats all. If you store the jsonString as
localStorage.setItem('ARjsMultiMarkerFile', jsonString);
then it will be used as the default multimarker file later on. If you want a custom name or more areas - then you'll have to modify the name in the source code.
3) 2.1.4 debugUI
It seems that the debug UI is broken - the UI buttons do exist but are nowhere to be seen. A hot fix would be using the 'markersAreaEnabled' span style for the div
containing the buttons (see this source bit).
It's all in this glitch, you can find it under the phrase 'CHANGES HERE' in the arjs code.