/**
 * Alpha Mask with PGraphics 
 * 
 * "img.jpg" is the background image that I load in backgroundimage."mask.jpg" is the grayscale image 
 * used as a mask. It's loaded in maskimage. Then maskimage is drawn to a PGraphics object and this 
 * PGraphics is used as the mask. (I couldn't use a PImage as a mask if it was not the applet's size.)
 * They must be in this sketch's data folder. Click to invert the mask...
 */

PImage maskimage;
PImage backgroundimage;
PGraphics pg;
PGraphics pg2;
int larg;
int haut;
String maskname="mask";
int i=0;
boolean inver=false;
int [] maskArray;

void setup() {
  size(800, 600);
  maskArray=new int[800*600];
  backgroundimage = loadImage("img.jpg");
  maskimage = loadImage(maskname+"0.jpg");
  larg=maskimage.width;
  haut=maskimage.height;
  backgroundimage.loadPixels(); 
  pg = createGraphics(800, 600, P2D);  
  //pg2=pg;
  imageMode(CENTER);
}

void draw() {
  background(0);  
  pg.beginDraw();
  pg.background(0);
  pg.fill(255);
  pg.image(maskimage, mouseX-maskimage.width/2, mouseY-maskimage.height/2);
  //pg2.image(maskimage,mouseX-larg/2,mouseY-haut/2);

  if (inver) {
    pg.filter(INVERT);
  }
  pg.endDraw();
  backgroundimage.mask(pg);
  image(backgroundimage, width/2, height/2);
}

void mousePressed() {
  if (mouseButton == RIGHT) {
    inver=!inver;
  }
}
void mouseReleased() {
  if (mouseButton == RIGHT) {
    inver=!inver;
  }else{
  i++;
  if (i>8) {
    i=0;
  }
  maskimage = loadImage(maskname+i+".jpg");
  }
}