color daColor;
PImage daPic;

int dotSpacing, maxDotSize;
float brightestPixel, dotSize;

void setup() {
  maxDotSize = 20;
  dotSpacing = 7;
  //dotSize = 7;
  daPic = loadImage("pretty.jpg");
  background(255);
  size(500,333);
  noStroke();
  smooth();
  //noLoop();
}

void draw() {
  brightnessCheck();
  int counter = 0;
  //dotSpacing = (int)map(mouseY, 0, height, 0, 20);
  for(int b = dotSpacing/2; b < height; b = b + dotSpacing){
    for(int a = dotSpacing/2; a < width; a = a + dotSpacing){
    //daColor = daPic.get(a, b);
    daColor = pixels[counter];
    int pixelValue = pixels[counter];
    float pixelBrightness = brightness(pixelValue);
    fill(daColor);
    dotSize = map(pixelBrightness, brightestPixel, 0, 0, maxDotSize);
    ellipse(a,b,dotSize,dotSize);
    counter = counter + dotSpacing;
    }
    counter = counter + ((width-(width/(dotSpacing)))*dotSpacing);
    //println(counter);
  }  

  
}

void brightnessCheck(){
  image(daPic,0,0);
 loadPixels();
 background(255);
for(int h = 0; h < pixels.length; h++){
 int pixelValue = pixels[h];
        // Determine the brightness of the pixel
        float pixelBrightness = brightness(pixelValue);
        // If that value is brighter than any previous, then store the
        // brightness of that pixel, as well as its (x,y) location
        if (pixelBrightness > brightestPixel) {
          brightestPixel = pixelBrightness;
} 
}
}

void keyPressed(){
    if(key == '=' || key == '+'){
    dotSpacing = dotSpacing + 1;
  }
   if(key == '-' || key == '_'){
    dotSpacing = dotSpacing - 1;
  } 
}