Rubik's cube implemented in Java Processing

cube.pde

int t;
int n;
int dir;
int axis;
int grid = 100;
int size = 80;

void setup() {
  size(854, 480, P3D);
  rnd();
  // fullScreen(P3D);
}

void rnd() {
  t = millis();
  n = int(random(0, 3)) - 1;
  dir = int(random(0, 2)) * 2 - 1;  
  axis = int(random(0, 3));
}

void draw() {
  lights();
  background(127);
  perspective(0.4 * PI, float(width) / float(height), 10, 10000.0);
  translate(width/2, height/2, 0);
  rotateX(PI*(0.5 - float(mouseY)/height));
  rotateY(PI*mouseX/width);
  if (millis() >= t + 1000) {
    rnd();
  };
  float rotation = dir * (t - millis()) / 1000.0 * PI / 2;
  for (int k=-1; k<2; k++) {
    for (int j=-1; j<2; j++) {
      for (int i=-1; i<2; i++) {
        if (i == n && axis == 0) {
          rotateX(rotation);
        };
        if (j == n && axis == 1) {
          rotateY(rotation);
        };
        if (k == n && axis == 2) {
          rotateZ(rotation);
        };
        translate(grid*i, grid*j, grid*k);
        box(size);
        translate(-grid*i, -grid*j, -grid*k);
        if (i == n && axis == 0) {
          rotateX(-rotation);
        };
        if (j == n && axis == 1) {
          rotateY(-rotation);
        };
        if (k == n && axis == 2) {
          rotateZ(-rotation);
        };
      };
    };
  };
}