Hello Processers!

I have newly discovered Processing and am working on a stop-motion project. I have become fluent with making images move left to right, and creating delays..

I want to create stop-motion animation that moves in a sequence of directions. Preferably the following sequence:
left to right
(break of no pictures)
right to left
(break)
downward
(break)
upward

I know I saw someone create a draw that moved images up and down rather than left to right, so I know it can be done. The only question is if the images can change direction and happen all at the same time.

This is what I have so far:

PImage foam;
int which;

void setup() {
size(900,700);
background(0);
which=1;
println("setting up");
}
void draw()  {
 background(0);
foam = loadImage("picture"+which+".JPG");
image(foam,10+which*60,10);
println("drawing");
which--;
if(which<1)
{which=5;

}
if (which==3 || which==5) {
delay(900);
} else
 delay(20);
}


It takes my images and moves them from right to left with a delay.



So can anyone help me? Does anyone know of any way to create these four separated moving sequences?

THANKS!