// climax.java
// succession and climax
// adapted from a program in basic by H.T. Odum & E. Odum, 1994

import java.applet.*;
import java.awt.*;

public class climax extends Applet
{

 Label prompt1, prompt2;
 TextField input1, input2;
 Button drawbutton;
 CheckboxGroup seeding;
 Checkbox with, without;
 double i, s, b, bi, d, di, k0, k1, k2, k3, k4, k5, k6, k7, k8, k9;
 double b0, g0, p0, d0, dt, t, ti, r, dd, pg, pgi, db, dbi;
 int a;
 Panel panel;

 public void init()
 {
 	prompt1 = new Label("K4 harvest: ");
	input1 = new TextField("25", 5);

	prompt2 = new Label("I energy source: ");
	input2 = new TextField("100", 5);

	drawbutton = new Button("Draw");

	seeding = new CheckboxGroup();
	with = new Checkbox("with seeding", seeding, true);
	without = new Checkbox("without seeding", seeding, false);

	panel = new Panel();
	panel.setLayout(new GridLayout(3,2,10,0));

	panel.add(prompt1); panel.add(input1);
	panel.add(prompt2); panel.add(input2);
	panel.add(with); panel.add(without);

	add(panel);
	add(drawbutton);
 }

 public boolean action(Event e, Object o)
 {
	if(e.target instanceof Checkbox) {
	  if(with.getState()==true) a=0;
	  else a=1;
	}
	k4 = 0.000001f*(float)Integer.parseInt(input1.getText());
 	i = 0.01f*(float)Integer.parseInt(input2.getText());
 	repaint();
 	return true;
 }

 public void paint(Graphics g)
 {
 	g.drawRect(0,90,320,250);
	t=0; ti=0;
	if (a==0) s=1;
	else s=0;
	b=100; d=1;
	k0=0.027f; k1=0.0002f; k2=2; k3=0.00417f; k5=0.01f;
	k6=0.000175f; k7=0.00004f; k8=0.000005f; k9=0.002f;
	b0=0.003f; g0=3; p0=3.2; d0=3; dt=10;

 	while ((t/15)<320)
 	{
		r=i/(1+k0*d+k1*b);
		dd=k8*b*s-k9*d-k7*d*d;
		pg=k2*r*d+k3*r*b;
		db=pg-k6*b-k4*b-k5*d*d;
		bi=b+db*dt;
		di=d+dd*dt;
		pgi=k2*r*di+k3*r*bi;
		dbi=pgi-k6*bi-k4*bi-k5*di*di;
		ti=t+dt;
		g.setColor(Color.blue);
		g.drawLine((int)t/15, (int)(340-d*d0), (int)ti/15, (int)(340-di*d0));
		g.setColor(Color.green);
		g.drawLine((int)t/15, (int)(340-b*b0), (int)ti/15, (int)(340-bi*b0));
		g.setColor(Color.orange);
		g.drawLine((int)t/15, (int)(340-pg*p0), (int)ti/15, (int)(340-pgi*p0));
		g.setColor(Color.pink);
		g.drawLine((int)t/15, (int)(340-db*g0), (int)ti/15, (int)(340-dbi*g0));
		t=ti;
		d=di; b=bi;
	}
 }
}
// Manuel Basler & E. Ortega,November 16th 2000