[chuck-users] KBHit events

[Moisés Gabriel Cachay Tello]

Hi, I'm a coursera's ChucK course student, in the lectures, Ge used HIDs to
handle keyboard input, so this snippet should help (I'm commenting the code
for clarity).

// HID stands for human-interface-device, also this is an event,
// see below for more info
Hid hid;

// This is a message, this will hold the event's (keypress) information.
HidMsg msg;

// We should define a device number since we would have multiple keyboards
// attached to our computer, 0 would do on most cases but you can try 1, or
2
// if that doesn't work.
0 => int device_number;

// We check if the device attach with ChucK was successful, otherwise the
program
// would end inmediately
if(!hid.openKeyboard(device_number)) me.exit();

<<<"Keyboard:", hid.name(), " ready!">>>;

// We setup a simple sound chain for demonstration pruposes only
BeeThree organ => JCRev rev => dac;
.05 => rev.mix;

// And repeat forever, see how the keyboard input is something that would
happen
// *forever*, a keypress can occur anytime so we need to stay alert until a
new
// event comes in
while(true) {
    // Events are things that happens sometime, in ChucK this mains
basically
    // hold ourselves until the event appears (thats why we wain for the
event
    // ChucKing it to now)
    hid => now;

    // When our wait finishes: check all the messages that came from the
keyboard
    // using the recv function, and passing msg as the holder of the
information
    while(hid.recv(msg)) {

        // we check if the message is a buttondown message, in that case:
        if(msg.isButtonDown()) {
            // We show the ascii value of the key pressed
            <<< "Button down:", msg.ascii >>>;

            // and make our generator sound, see how we check if the
            // frequency too much high we simply discard this message
            msg.ascii => Std.mtof => float freq;
            if(freq > 20000) continue;

            freq => organ.freq;
            1 => organ.noteOn;

            // this will make sure the sound will keep for a minimum amount
of
            // time, otherwise, concurrent events may stop before even
commencing
            80::ms => now;
        } else {
            // If we're not in a buttondown event, just assume it's a key
has been
            // left out and shut down the sound.
            <<< "Button up:", msg.ascii >>>;
            1 => organ.noteOff;
        }
    }

}



2013/12/5 Manuel Bärenz <manuel at enigmage.de>

>  Hi Julien,
>
> No, this is not the case. KBHits are only key down events. I tried to
> include several kb => now, but it didn't help.
> See also this example here:
> http://chuck.cs.princeton.edu/doc/examples/event/kb2.ck
> Apparently, the solution is emptying the event queue by calling
> kb.getchar() until kb.more() returns false:
>
>
> KBHit kb;
>
> me.sourceDir() + "/bum.wav" => string filename;
>
> adc => WvOut b => blackhole;
> filename => b.wavFilename;
> kb => now;
> while(kb.more()) kb.getchar();
>
> b.closeFile();
>
> SndBuf buf => dac;
> filename => buf.read;
> kb => now;
>
> The important line is "while(kb.more()) kb.getchar();", apparently. So I
> guess kb => now; doesn't wait at all if there are still unprocessed keys in
> the queue.
>
> Best, Manuel
>
> Am 05/12/13 12:18, schrieb Julien Saint-Martin:
>
>   Hi Manuel,
>
>  Maybe your problem is as follow:
> For each key press there is two kb events: key down and key up.
>
>  A simple solution maybe to write "kb => now;" twice.
>
>  Cheers,
>  Julien
>
>
>
>
>
> 2013/12/5 Manuel Bärenz <manuel at enigmage.de>
>
>> Hello again,
>>
>> I also wanted to demonstrate a simple sequencer prototype that lets me
>> record a file and then plays it back to me. I've come this far:
>>
>> KBHit kb;
>>
>> me.sourceDir() + "/bum.wav" => string filename;
>>
>> adc => WvOut b => blackhole;
>> filename => b.wavFilename;
>> kb => now;
>> b.closeFile();
>>
>> SndBuf buf => dac;
>> filename => buf.read;
>> kb => now;
>>
>> But strangely, the program doesn't wait for the second kb event, but
>> exits directly after the first key that I hit. Any ideas what I'm doing
>> wrong?
>>
>> Best, Manuel
>> _______________________________________________
>> chuck-users mailing list
>> chuck-users at lists.cs.princeton.edu
>> https://lists.cs.princeton.edu/mailman/listinfo/chuck-users
>>
>
>
>
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-- 
-Moisés
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