Make only some random pixels change colour

elf

Howdy!

So I'm an avid happy sonic media student and learning processing is part of an installation I want to make...

Here's my problem/question.

I have created some white noise, which I would like to decrease over time (change starting after 2 secs, intensifying after 10 secs etc), tending towards a black screen.

What I can't figure out is, how can I make only some (say, 50% of all pixels) random pixels change colour, while the rest is just black, within the same frame?

So far I could only make all of them change randomly, or all of them stay black. Any help would be much appreciated, thank you!!

void setup() {
  size(1000, 800);
}

void draw() {
  if (millis() < 2000) {
    loadPixels();
    for ( int i=0; i<pixels.length; i++)
      pixels[i] = color(random(255));
    updatePixels();
  }

  if (millis() > 2000) {
            loadPixels();
            for ( int i=0; i<pixels.length; i++)
              pixels[i] = color(random(255));
            updatePixels();
            loadPixels();
            for ( int j=0; j<pixels.length; j++)
              pixels[j] = color(0);
            updatePixels();
          }
        }
      }

    if (millis() > 10000) {
      loadPixels();
      for ( int i=0; i<pixels.length; i++)
        pixels[i] = color(random(255));
      updatePixels();
    }
  }

_vk

One empty line before, one after. Select the code, hit ctr-o. Code formatted.

Similar problem

https://forum.processing.org/two/discussion/13712/how-to-add-noise-to-the-image-being-drawn#latest

elf

Thanks! Wasn't aware of the empty line before and after. Hmm, I tried playing around with the suggestions from the other thread, but I can't think of a way to apply it to this one. What I want is that for 50% of the pixels (randomly selected) it's: color(random(255)) For the other 50% it's color(0).

Thanks again!

_vk

It is there, but here it is...

int heads, tails;
void draw() {
  if (random(1) >= 0.5) {
    println("Head");
    heads++;
  } else {
    println("Tail");
    tails++;
  }

  if (frameCount > 200) {
    println( heads + " heads and\n" + tails + " tails have been draw");
    exit();
  }
}