Hi all,

I am trying to modify the pixels of an image based on the movement of the mouse. I know it is basic, but i am having a hard time figuring out how to do the following:

As mouseY increases, i would like to have the % of the image pixels that appear in the sketch increase. HOWEVER, how can i make this happen so that their position is random, but there quantity is still  related to the mouseY value. Here is my basic attempt without random positioning

PImage arch;

void setup() {
 size(449, 315);
 arch = loadImage("housingthun02.jpg");
}

void draw() {
 background(arch);  
 loadPixels();
 for (int i = 0; i < width*height; i++) {
   color p = pixels[i]; //
   float r = red(p);
   float g = green(p);
   float b = blue(p);
   float bw = (r + g + b) / 3.0;
   bw = constrain(bw + mouseY, 0, 255);
   pixels[i] = color(bw);    
}
updatePixels();
line(0, mouseY, 50, mouseY);
}


Any help would be greatly appreciated. Thanks

Maybe this does what you want:

Code:

void draw() {
  background(arch);  
  loadPixels();
  for (int i = 0; i < width*height; i++) {
   if (random(1) < (float)mouseY/height)  // with probability proportional to mouse Y position...
     pixels[i] = color(0);  // ... erase this pixel
  }
  updatePixels();
  line(0, mouseY, 50, mouseY);
} 

If you want to have non-dynamic noise, replace "random(1)" with "noise(i)", although that doesn't look as interesting.