// Display an interactive dancing stick figure

//The "import" statements tell the Java compiler
//to add in the pre-built code that comes with Java.
//For example "import java.net.*;" makes sure all
//of the networking tools are available.
import java.awt.*;
import java.net.*;
import java.util.*;

//The web page which runs this applet
//calls it with an applet tag that looks like
//<applet>code=StickFigureApplet width=300 height=500</applet>
//The width and height are pretty self explanitory.
//The "code" part points to the class to start running
//and calls its start() function. StickFigureApplet
//does not have a start() function, so Java looks for
//GenericApplet's start()  since that is the class
//StickFigureApplet is extended from
public class StickFigureApplet extends GenericApplet
{
   //GraphicFigure is defined below
   GraphicFigure f;

   //Be careful with the render() functions! This render()
   //function is derived from GenericApplet, while f.render()
   //is derived from KFMFile

   //damage is defined in Generic Applet as
   //true in order to force the first render
   public void render(Graphics g) {
      if (damage) {
	 if (f == null)
            //if it doesn't exist, create a new GraphicFigure
            //passing in the URL and the string "StickFigure".
            //getCodeBase() returns the current URL
            f = new GraphicFigure(getCodeBase(), "StickFigure");
         g.setColor(Color.white);
         g.fillRect(0, 0, bounds().width, bounds().height);
         g.setColor(Color.black);
	 //call the render function from GraphicFigure (below)
	 f.render(g);
      }
   }

   double t = 0.;
   //public boolean mouseDrag() is a "magic" function that is
   //never explicitly called. Defining this function tells
   //Java that whenever it detects the mouse being dragged,
   //it is supposed to stop whatever it is doing and run
   //this function
   public boolean mouseDrag(Event e, int x, int y) {
      //make sure the figure is drawn by setting damage
      damage = true;
      t += .2;
      //cyle through all joints in the figure and rotate them
      for (int i = 0 ; i < f.size() ; i++)
	 if (f.name(i) != null) {	//only joints have names
	    f.matrix(i).rotateX(1.2*Math.cos(   i + .678*t));
	    f.matrix(i).rotateY(1.2*Math.cos(.9*i + .890*t));
	    f.matrix(i).rotateZ(1.2*Math.cos(.8*i +      t));
	 }
      return true;
   }
}

class GraphicFigure extends KVMFile
{
   //This is the constructor for GraphicFigure and is automatically
   //called any time a new GraphicFigure is created. The line
   //"super(context, URLName)" calls the constructor of KVMFile
   //since that is the class GraphicFigure is extended from
   GraphicFigure(URL context, String URLName) { super(context, URLName); }

   Graphics g;
   //public void render is an inherited function that renders what
   //the figure looks like. However, since this function overrides its parent
   //render() function, the actual code must be reprogrammed or it
   //is lost. To get around this, the render() of its parent can
   //be called with super.render(). Also, make sure you don't
   //confuse GraphicFigure's render() with StickFigureApplet's
   //render(); they are derived from different places!
   public void render(Graphics g) {
      this.g = g;
      super.render();
   }
   //This function actually draws the line for the figure
   //(See the Java documentation for info on drawLine())
   public void drawLine(double x1, double y1, double x2, double y2) {
      g.drawLine((int)(3*x1), (int)(3*y1), (int)(3*x2), (int)(3*y2));
   }
   //Joints don't need to be drawn so the function is blank
   public void drawJoint(String name, double x, double y) { }
}