Update that allows to select a device

Hi!

I made a little update to this script that will print all the connected devices `name` and `id` to the console. You can then use a specific device by adding `device = <name|id>` to the code.

I also adjusted the normalization so it actually normalizes 0-1, but maybe you want to put this back to how it was. Previously it would not have 0 as the lowest value because a `1` was added before division.

Let me know what you think! :)

docs/midi.md

@@ -11,15 +11,19 @@ This is a generic script that doesn't care what Midi Channel you're broadcasting
 This portion should be ran in the console & will register Web MIDI & map the incoming CC data to a set of parameters. For simplicity, these
 parameters are named to match the CC number. The CC values are normally in a range from 0-127, but we've also normalized them to be in a range of 0.0-1.0.
 
-```
+```js
 // register WebMIDI
 navigator.requestMIDIAccess()
     .then(onMIDISuccess, onMIDIFailure);
 
 function onMIDISuccess(midiAccess) {
-    console.log(midiAccess);
+    // console.log(midiAccess);
     var inputs = midiAccess.inputs;
     var outputs = midiAccess.outputs;
+    
+    console.log('Available MIDI Inputs & ID:')
+    inputs.forEach((i) => console.log(i.name, i.id)) 
+   
     for (var input of midiAccess.inputs.values()){
         input.onmidimessage = getMIDIMessage;
     }
@@ -29,22 +33,36 @@ function onMIDIFailure() {
     console.log('Could not access your MIDI devices.');
 }
 
-//create an array to hold our cc values and init to a normalized value
-var cc=Array(128).fill(0.5)
+// Create an array to hold our cc values and init to a normalized value
+var cc = Array(128).fill(0.5);
+
+// Change the device name to one of the names (or ID) from the available midi 
+// inputs to make sure Hydra only reacts to the input of that controller
+var controller = null;
 
 getMIDIMessage = function(midiMessage) {
-    var arr = midiMessage.data    
-    var index = arr[1]
-    //console.log('Midi received on cc#' + index + ' value:' + arr[2])    // uncomment to monitor incoming Midi
-    var val = (arr[2]+1)/128.0  // normalize CC values to 0.0 - 1.0
-    cc[index]=val
+    var dev = midiMessage.target.name;
+    var id = midiMessage.target.id;
+    
+    // Only set midi values if the input equals the device name or id (or is null)
+    if (dev === controller || id == controller || !controller){
+        var arr = midiMessage.data;
+        var index = arr[1];
+
+        // Normalize CC values to 0.0 - 1.0
+        cc[index] = arr[2] / 127;
+
+        // Uncomment to monitor incoming Midi
+        // console.log(`Midi received: cc#${index}, value: ${arr[2]}, norm: ${cc[index]}`);
+    }
 }
 ```
 
 ### Hydra script
 Now that these controls have been assigned to the cc[] array, we can start using them in Hydra.  As we've normalized the values 0-1 we can use
 as-is with most functions or quickly remap them with various math.  
-```
+
+```js
 // example midi mappings - Korg NanoKontrol2 CCs
 
 // color controls with first three knobs
@@ -54,3 +72,16 @@ noise(4).color( ()=>cc[16], ()=>cc[17], ()=>cc[18] ).out()
 osc(10,0.2,0.5).rotate( ()=>(cc[0]*6.28)-3.14 ).scale( ()=>(cc[1]) ).out()
 
 ```
+
+### Select specific controller
+If you have multiple MIDI controllers connected to your computer Hydra will pick up the values from all controllers. You can select a specific device by adding the name of the device as a string to the `device` variable. You can find the list of connected devices with name and ID printed to the console.
+
+```js
+controller = "Korg NanoKontrol2"
+```
+
+In the case you have multiple controllers with the same name you can also use the devices ID like so:
+
+```js
+controller = -1511378908
+```