// Sierpinsky Gadget in JavaGL

import java.applet.Applet;
import java.awt.*;
import java.util.Random;

// must import javagl.GL....
import javagl.GL;
import javagl.GLAUX;

public class Gasket extends Applet {
    // must use GL to use JavaGL.....
    // and use GLAUX to use the aux functions.....
    // remember to give GL to initialize GLAUX
		GL gl = new GL ();
		GLAUX aux = new GLAUX (gl);

		float vertices[][]={{(float)0.0,(float)0.0},
							{(float)250.0,(float)500.0},
							{(float)500.0,(float)0.0}};
		float p[] = {(float)75.0,(float)50.0}; 
		Random rand = new Random(0);

    public void start () {
		// Do off-line drawing
		gl.glClearColor((float)1.0,(float)1.0,(float)1.0,(float)1.0); /* white background */
		gl.glClear(GL.GL_COLOR_BUFFER_BIT);  /*clear the window */
		gl.glColor3f((float)1.0,(float)0.0,(float)0.0); /* draw in red */

		/* set up viewing */
		/* 500 x 500 window with origin lower left */

		gl.glMatrixMode(GL.GL_PROJECTION);
		gl.glLoadIdentity();
		gl.glOrtho((float)0.0,(float)500.0,(float)0.0,(float)500.0,(float)-1.0,(float)1.0);
		gl.glMatrixMode(GL.GL_MODELVIEW);	

		int i=0, j=0, k=0;

/* computes and plots 5000 new points */

		for( k=0; k<5000; k++)
		{
			j=Math.abs(rand.nextInt()%3); /* pick a vertex at random */

     /* Compute point halfway between vertex and old point */

			p[0] = (p[0]+vertices[j][0])/(float)2.0; 
			p[1] = (p[1]+vertices[j][1])/(float)2.0;

     /* plot new point */

	       gl.glBegin(GL.GL_POINTS);
		         gl.glVertex2fv(p); 
	       gl.glEnd();
	
		}
		gl.glFlush(); /* clear buffers */
    }

    public void paint (Graphics g) {
		gl.glXSwapBuffers (g, this);
    }

    public void init () {
    	aux.auxInitPosition (0, 0, 500, 500);
		aux.auxInitWindow (this);
    }
}