I've been surfing through a lot of old P5.js questions and ran into this question: p5.js code isnt executing when spacebar is pressed in combiniation with up and left I tried out a few of my ideas in the editor (which didn't work), then I made this little test program:
function setup(){
createCanvas(200, 200);
}
function draw() {
background(220);
textAlign(CENTER, CENTER);
text( keyCode, width/2, height/2 );
let lettersPressed = "";
let toKeyCode = k => {
return 65 + "abcdefghijklmnopqrstuvwxyz".split("").indexOf(k);
}
"abcdefghijklmnopqrstuvwxyz".split("").forEach(l => {
lettersPressed += keyIsDown(toKeyCode(l)) ? l : "-";
});
text(lettersPressed, width/2, height/1.7);
}<script src="https://cdnjs.cloudflare.com/ajax/libs/p5.js/1.1.9/p5.min.js"></script>The first number is the keycode of the most recent key press. The letters/dashes after that is all the letters in the alphabet that are being pressed.
THE QUESTION
When I press down the a, b, and c key they all show up. But when I press the d key on top of that, the d key doesn't show. This is a very similar problem to the SO I linked. The weird part is you can press the e key and it works. This is a pattern throughout other combinations of keys as well. Is their a reason for this?
This has nothing to do with p5.js, it has everything to do with the physical keyboard you're using and your computer/operating system/drivers.
Keyboards can only transfer so much data, so they limit the number of keys that they report pressed at any given time. Sometimes they do this to X number of keys per area.
Watch Ben Eater's How does a USB keyboard work? for more details, as well as How does n-key rollover work?.
The way keyboards are wired prevents them from detecting multiple keys in certain combinations, so it will ignore the extra keys in what's known as N-key rollover. It's not p5.js at all.
You can look at this link: