int w = 800;
int h = 600;

int count = 0;
float r = w * 2;
float zoom = 0;
float xangle = 0;

String[] slidefiles = {
"slide01.jpg",
"slide02.jpg",
"slide03.jpg",
"slide04.jpg"
};

PImage img;
PImage[] slides;

void setup() {
  size(w, h, P3D);
  slides = new PImage[slidefiles.length];
  for(int frame = 0; frame < slidefiles.length; frame++){
    slides[frame] = loadImage(slidefiles[frame]);          
  }
  img = slides[0];
  noStroke();
  frameRate(30);
}

void draw() {
  background(0);
  translate(0, 0, -r + zoom);
  
  int frame;
  float sector = 0;
  float sectorstep = 2 * PI / slides.length;
  for(frame = 0; frame < slides.length; frame++){
    sector += sectorstep;
    pushMatrix();
    rotateY(xangle + sector);
    translate(w/2, h/2, r);
    scale(w, h);
    beginShape();
    texture(slides[frame]);
    vertex(-0.5, -0.5, 0, 0, 0);
    vertex(0.5, -0.5, 0, img.width, 0);
    vertex(0.5, 0.5, 0, img.width, img.height);
    vertex(-0.5, 0.5, 0, 0, img.height);
    endShape();
    popMatrix();
  }
  if(count % (64 * slides.length) == 0){
    xangle = 0;
    zoom = 0;
  }
  int ticker = count % 64;
  if((16 <= ticker) && (ticker < 32)){
    zoom -= r/16;
  }  
  if((32 <= ticker) && (ticker < 48)){
    xangle -= PI/32;
  }
  if((48 <= ticker) && (ticker < 64)){
    zoom += r/16;
  }
  count++;
}