FractalTree4.java

public class FractalTree4 {

  public static void main(String[] args) {
    Turtle t = new Turtle();
    t.delay(0);
    t.left(90);
    tree(t, 150, 10);
  }

  public static void tree(Turtle t, double size, int level) {
    int red = 255 / (level + 1);
    int green = 255 - (255 / (level + 1));
    int blue = 0;
    t.color(red, green, blue);
    if (level == 0) {
        t.forward(size);
        t.penup();
        t.backward(size);
        t.pendown();
    } else {
        // stem
        t.forward(size);
        // first branch
        double tilt1 = Math.random() * 30 - 15; //random angles
        t.left(30 + tilt1);
        tree(t, size * 0.8, level - 1);
        // second branch
        double tilt2 = Math.random() * 30 - 15;
        t.right(30 + tilt1 + 45 + tilt2);
        tree(t, size * 0.6, level - 1);
        t.left(45 + tilt2);
        t.penup();
        t.backward(size);
        t.pendown();        
    }
  }
}