Hey Moisés,

Thanks again for this more sophisticated example. I'm having problems with HIDs, I constantly get this error:

HidIn: couldn't open keyboard 0...
I get the error for all values from 0 to 5. I'm using Gentoo Linux. For tonight's presentation, I'm going to stick with KBHit probably.

Best, Manuel

Am 05/12/13 17:43, schrieb 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@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@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
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--
-Moisés

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