// based on mouse_color by kll

​

let infile = 'assets/galaxy.jpg';

let showorg = false;

let rad = 100;

​

function preload() {

  img = loadImage(infile);

}

​

function setup() {

  createCanvas(800, 450);

  pixelDensity(1);

  img.loadPixels();

  loadPixels();

}

​

function draw() {

  // optionally show original image

  if (showorg){

    image(img, 0, 0);

    return;

  }

  loadPixels();

  // set black background

  pixels.fill(0);

  for(let i=0; i<pixels.length/4; i++){

    pixels[i*4+3] = 255;

  }

  // compute spotlight for area only

  let minx = max(mouseX-rad,0);

  let miny = max(mouseY-rad,0);

  let maxx = min(mouseX+rad,width);

  let maxy = min(mouseY+rad,height);

  for (let x = minx; x < maxx; x++) {

    for (let y = miny; y < maxy; y++) {

      let loc = (x + y * img.width) * 4; //___ Calculate the 1D location from a 2D grid

      let r, g, b; //_________________________ Get the R,G,B values from image

      r = img.pixels[loc];

      g = img.pixels[loc + 1];

      b = img.pixels[loc + 2];

      // Calculate an amount to change brightness based on proximity to the mouse

      let maxdist = 50;

      let d = dist(x, y, mouseX, mouseY);

      let adjustbrightness = (255 * (maxdist - d)) / maxdist;

      r += adjustbrightness;

      g += adjustbrightness;

      b += adjustbrightness;

      // Constrain RGB to make sure they are within 0-255 color range

      r = constrain(r, 0, 255);

      g = constrain(g, 0, 255);

      b = constrain(b, 0, 255);

      // Make a new color and set pixel in the window

      let pixloc = (y * width + x) * 4;

      pixels[pixloc] = r;

      pixels[pixloc + 1] = g;

      pixels[pixloc + 2] = b;

      pixels[pixloc + 3] = 255;

    }

  }

  updatePixels();

}

​

function keyPressed() {

  if (key == 'o') showorg = !showorg;

}

​