class PenroseLSystem extends LSystem {
  
    int steps = 0;
    float somestep = 0.1;
    String ruleW;
    String ruleX;
    String ruleY;
    String ruleZ;
  
    PenroseLSystem() {
      axiom = "[X]++[X]++[X]++[X]++[X]";
      ruleW = "YF++ZF4-XF[-YF4-WF]++";
      ruleX = "+YF--ZF[3-WF--XF]+";
      ruleY = "-WF++XF[+++YF++ZF]-";
      ruleZ = "--YF++++WF[+ZF++++XF]--XF";
      startLength = 460.0;
      theta = radians(36);  
      reset();
    }
  
    void useRule(String r_) {
      rule = r_;
    }
  
    void useAxiom(String a_) {
      axiom = a_;
    }
  
    void useLength(float l_) {
      startLength = l_;
    }
  
    void useTheta(float t_) {
      theta = radians(t_);
    }
  
    void reset() {
      production = axiom;
      drawLength = startLength;
      generations = 0;
    }
  
    int getAge() {
      return generations;
    }
  
    void render() {
      translate(width/2, height/2);
      int pushes = 0;
      int repeats = 1;
      steps += 12;          
      if (steps > production.length()) {
        steps = production.length();
      }
  
      for (int i = 0; i < steps; i++) {
        char step = production.charAt(i);
        if (step == 'F') {
          stroke(255, 60);
          for (int j = 0; j < repeats; j++) {
            line(0, 0, 0, -drawLength);
            noFill();
            translate(0, -drawLength);
          }
          repeats = 1;
        } 
        else if (step == '+') {
          for (int j = 0; j < repeats; j++) {
            rotate(theta);
          }
          repeats = 1;
        } 
        else if (step == '-') {
          for (int j =0; j < repeats; j++) {
            rotate(-theta);
          }
          repeats = 1;
        } 
        else if (step == '[') {
          pushes++;            
          pushMatrix();
        } 
        else if (step == ']') {
          popMatrix();
          pushes--;
        } 
        else if ( (step >= 48) && (step <= 57) ) {
          repeats = (int)step - 48;
        }
      }
  
      // Unpush if we need too
      while (pushes > 0) {
        popMatrix();
        pushes--;
      }
    }
  
    String iterate(String prod_, String rule_) {
      String newProduction = "";
      for (int i = 0; i < prod_.length(); i++) {
        char step = production.charAt(i);
        if (step == 'W') {
          newProduction = newProduction + ruleW;
        } 
        else if (step == 'X') {
          newProduction = newProduction + ruleX;
        }
        else if (step == 'Y') {
          newProduction = newProduction + ruleY;
        }  
        else if (step == 'Z') {
          newProduction = newProduction + ruleZ;
        } 
        else {
          if (step != 'F') {
            newProduction = newProduction + step;
          }
        }
      }
  
      drawLength = drawLength * 0.5;
      generations++;
      return newProduction;
    }
  
  }