3d turtle and stuff

3dturle.pde

import java.util.*;

String system;
String system2;
Turtle t;

class Turtle {
  Stack st;

  float x, y,z; // Current position of the turtle
  float angle = -90; // Current heading of the turtle
  boolean penDown = true; // Is pen down?

  // Set up initial position
  Turtle (float xin, float yin) {
    x = xin;
    y = yin;
    z = -500;
    st = new Stack();

  }

  // Move forward by the specified distance
  void forward (float distance) {

    // Calculate the new position
    float xtarget = x+cos(radians(angle)) * distance;
    float ytarget = y+sin(radians(angle)) * distance;

    // If the pen is down, draw a line to the new position
    if (penDown) line(x, y, z, xtarget, ytarget, z);

    // Update position
    x = xtarget;
    y = ytarget;

  }

  void push() {
    st.push( new Float[]{x,y,z} );
  }

  void pop() {
    Float[] a = (Float []) st.pop();
    x = a[0];
    y = a[1];
    z = a[2];
  }

  void down(float distance) {
    z = z + distance;
  }

  void up(float distance) {
    z = z - distance;
  }

  // Move back by specified distance
  void back (float distance) {
    forward(-distance);
  }

  // Turn left by given angle
  void left (float turnangle) {
    angle -= turnangle;
  }

  // Turn right by given angle
  void right (float turnangle) {
    angle += turnangle;
  }

  // Set the pen to be up
  void penUp() {
    penDown = false;
  }

  // Set the pen to be down
  void penDown() {
    penDown = true;
  }
}



void setup() {
  size(1920,1200,P3D);

  t = new Turtle(width*4, -height*3);
  system = new String("aa");
  system2 = new String();

  println("Building String");
  for (int i=0; i < 6; i++) {
    for (char ch: system.toCharArray()) {

      if (ch == 'a') {
        system2 += "abab";
      } else if (ch =='b') {
        system2 += "bba[aa]b";
      } else {
        system2 += ch;
      }

    }

    system = system2;
  }

  println("Drawing Image");
  lights();
  background(255);
  rotateY(radians(20));
  rotateX(radians(50));
  rotateZ(radians(-60));
  for (char ch: system.toCharArray()) {
    if (ch == 'a') {
      t.left(90);
      t.forward(50);
      t.left(90);
      t.forward(50);
    } else if (ch =='b') {
      t.right(90);
      t.forward(50);
      t.right(90);
      t.forward(50);
      t.left(90);
      t.forward(50);
    } else if (ch == '[') {
      t.push();
      t.up(1500);

    } else if (ch == ']') {
      t.pop();
    }

  }

  saveFrame("ls_out.jpg");
}


void draw() {



}