// interact.java
// two populations with competitive interactions
// adapted from a program in basic by H.T. Odum & E. Odum, 1994

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

public class interact extends Applet
{

 Label prompt1, prompt2, prompt3;
 TextField input1, input2, input3;
 Button drawbutton;
 double E, Q1, Q1i, Q2, Q2i, D1, D2, K1, K2, K3, K4, K5, K6, t, ti;

 public void init()
 {
	drawbutton = new Button("Draw");
	add(drawbutton);

 	prompt1 = new Label("E Energy concentration: ");
	input1 = new TextField("100", 5);
	add(prompt1); add(input1);

	prompt2 = new Label("K5 first interaction coefficient: ");
	input2 = new TextField("2", 5);
	add(prompt2); add(input2);

	prompt3 = new Label("K6 second interaction coefficient: ");
	input3 = new TextField("1", 5);
	add(prompt3); add(input3);
 }

 public boolean action(Event e, Object o)
 {
 	E = (float)Integer.parseInt(input1.getText());
 	K5 = (float)Integer.parseInt(input2.getText());
	K6 = (float)Integer.parseInt(input3.getText());
 	repaint();
 	return true;
 }

 public void paint(Graphics g)
 {
 	g.drawRect(0,90,320,180);
	t=0;
	E=E/100; K1=0.07f; K2=0.08f; K3=0.002f; K4=0.001f; K5=K5/1000; K6=K6/1000;
	Q1=3;Q2=3;

 	while (t<320)
 	{
		ti=t+1;
		D1=K1*E*Q1-K3*Q1*Q1-K5*Q1*Q2;
		D2=K2*E*Q2-K4*Q2*Q2-K6*Q1*Q2;
		Q1i=Q1+D1;
		Q2i=Q2+D2;
		g.setColor(Color.blue);
		g.drawLine((int)t, (int)(270-Q1), (int)ti, (int)(270-Q1i));
		g.setColor(Color.green);
		g.drawLine((int)t, (int)(270-Q2), (int)ti, (int)(270-Q2i));
		t=ti; Q1=Q1i; Q2=Q2i;
	}
 }
}
// Manuel Basler & E. Ortega, October 17th 2000*/