// Drawing trees with turtles.

import java.awt.*;       // Import Abstract Window Toolkit
import java.applet.*;    // Import Applet stuff

public class TreeWorld extends TurtleWorld 
{
    String parameterNames [] = {"Levels", "Length", "Angle", "ShrinkFactor"};
    String parameterFields [] = {"7", "75", "30", "0.8"};
    ParameterFrame params;

    //------------------------------------------------------------------------------
     // The following main method is needed to run the applet as an application
     public static void main (String[] args) {
       runAsApplication(new TreeWorld(), "TreeWorld"); 
     }
     //------------------------------------------------------------------------------
    
    public void setup() 
    {
        params = new ParameterFrame("Tree Parameters",
                                    TurtleWorld.frameSize, 0,
                                    225, 170, 
                                    parameterNames, parameterFields);
    }
     
    public void run() 
    {
        TreeMaker trina = new TreeMaker();
        // Move to position in bottom center, facing up
        trina.pu();
        trina.lt(90);
        trina.bd((this.getSize().height)/2);
        trina.pd();
          
        // Draw tree
        trina.tree(params.getIntParam("Levels"), 
                   params.getDoubleParam("Length"), 
                   params.getDoubleParam("Angle"), 
                   params.getDoubleParam("ShrinkFactor"));
    }
}

class TreeMaker extends Turtle
{
    public void tree (int levels, double length, double angle, double shrink)
    {
        if (levels <= 0) {
            // Do nothing
        } else {
            fd(length);
            rt(angle);
            tree(levels - 1, length * shrink, angle, shrink);
            lt(2*angle);
            tree(levels - 1, length * shrink, angle, shrink);
            rt(angle);
            bd(length);
        }
    }
}