/** * Alpha Mask.  *  * Loads a "mask" for an image to specify the transparency  * in different parts of the image. The two images are blended * together using the mask() method of PImage.  */ PImage img;PImage maskImg;void setup() {  size(200,200);  img = loadImage("test.jpg");  maskImg = loadImage("mask.jpg");  img.mask(maskImg);}void draw() {  background((mouseX+mouseY)/1.5);  image(img, 50, 50);  image(img, mouseX-50, mouseY-50);}