// Copyright 1997 Liceo Scientifico Alberti // This applet and associated documentation and files may be distributed in // its entirety for non-commercial purposes only, provided this copyright // notice is included in every copy made. All other rights reserved by the author. // This applet and associated documentation and files are provided "as is" // with no warranty of any kind, either expressed or implied, including, but // not limited to the implied warranties of merchantability, fitness for a // particular purpose, and non-infringement. // This applet has been based on the nice NASA applets by Kelly Jo Brown // Programmer: Roberto De Leo import java.awt.*; import java.applet.*; import java.lang.*; import java.util.*; public class Keplero extends Applet implements Runnable{ private Button startbutton; private Button stopbutton; Orbita orbita = null; Graphics img,oldbackg; Vettore vi,Rversd,Fversd; UniVettore Rvers,Fvers; double RadInSp,AngInSp,Energy,MomAng; Satellite startingPoint = null, sun = null; Image screen,bar,slider,title,earea,oldback; Thread kicker = null; int runningFlag = 0; int emode=0,j=0; int div = 40; double k = 800000; int px=90,py=0,oldx=90,oldy=0,slide=50; double angle=0.0,anglei=.0,Anglei=0.,time=0,delta_time=.1,dist=0.,radius=0.,e=0; boolean draw_s=true,draw_t=true; static final double RAD_FACT=Math.PI/180; long begin_time; int pause; int posx = 425; int posDx= 40; int posDX= 80; int posy = 85; int posz = 35; Font TimesRoman = new Font("TimesRoman",Font.BOLD,14); public void run() { double delta_angle; while(kicker != null) { // Get current time in miliseconds for constant frame rate begin_time=System.currentTimeMillis(); if( runningFlag == 1 ){ // Calculate Radius radius = Traiettoria(vi,dist,e,Rversd,Fversd,angle,anglei,Anglei)/dist; // Calculate angle delta delta_angle=segno(Fvers.getDx()*vi.getDx() + Fvers.getDy()*vi.getDy())*RAD_FACT*2*Math.PI*Math.sqrt(1-e*e)/(radius*radius)*delta_time; // Add deltas angle = angle + runningFlag*delta_angle; // Calculate Coordinates px = (int) (Traiettoria(vi,dist,e,Rversd,Fversd,angle,anglei,Anglei)*Math.cos(angle)) - 5; py = (int) (Traiettoria(vi,dist,e,Rversd,Fversd,angle,anglei,Anglei)*Math.sin(angle)) - 5; } repaint(); // Calculate pause to give us constant frame rate pause= Math.abs(50 - (int)(System.currentTimeMillis() - begin_time)); try {Thread.sleep(pause);} catch (InterruptedException e){}; } } public void init() { int i; startbutton = new Button("start"); startbutton.setForeground(Color.white); startbutton.setForeground(Color.red); add(startbutton); stopbutton = new Button("stop"); stopbutton.setForeground(Color.white); stopbutton.setForeground(Color.red); add(stopbutton); // Create space for old background oldback=createImage(25,25); oldbackg=oldback.getGraphics(); } public void start() { if(kicker == null) { kicker = new Thread(this); kicker.start(); } } public void stop() { if(kicker != null) { kicker.stop(); kicker = null; } } public boolean mouseDown(Event evt, int x, int y) { //set the starting position if( x>0 && x<420 && y>40 && y<400){ if( runningFlag == 1 ){ runningFlag = 0; } if(orbita != null){ orbita.Clear(); } //Get the angle between planet-sun and x-axis angle = Math.atan((double) (y - sun.getY() - 5)/(x - sun.getX() - 5)); if( (y - sun.getY() - 5)>0 && (x - sun.getX() - 5)<0){ angle = angle + Math.PI; } else if( (y - sun.getY() - 5)<0 && (x - sun.getX() - 5)<0){ angle = angle - Math.PI; } while( angle > 2*Math.PI || angle < 0 ){ if( angle > 2*Math.PI ) { angle += -2*Math.PI; } if( angle < 0 ) { angle += 2*Math.PI; } } //define and draw reference frame and starting velocity if( startingPoint != null ){ startingPoint.Clear(); vi.Clear(); Rversd.Clear(); Fversd.Clear(); } startingPoint = new Satellite(img,Color.blue,x-8,y-8); startingPoint.Draw(); vi = new Vettore(img,Color.white,x-2,y-2,x+30,y-2); vi.Draw(); Rversd = new Vettore(img,Color.red,x-2,y-2,x-2+(int)(60*startingPoint.getX(sun)/startingPoint.getDist(sun)), y-2+(int)(60*startingPoint.getY(sun)/startingPoint.getDist(sun))); Fversd = new Vettore(img,Color.green,x-2,y-2,x-2-(int)(60*startingPoint.getY(sun)/startingPoint.getDist(sun)),y-2+(int)(60*startingPoint.getX(sun)/startingPoint.getDist(sun))); Rversd.Draw(); Fversd.Draw(); Rvers = new UniVettore(0,0, startingPoint.getX(sun),startingPoint.getY(sun)); Fvers = new UniVettore(0,0,-startingPoint.getY(sun),startingPoint.getX(sun)); RadInSp = Rvers.getDx()*vi.getDx() + Rvers.getDy()*vi.getDy(); AngInSp = (Fvers.getDx()*vi.getDx() + Fvers.getDy()*vi.getDy())/startingPoint.getDist(sun); MomAng = startingPoint.getDist(sun)*startingPoint.getDist(sun)*AngInSp; Energy = (RadInSp*RadInSp+MomAng*MomAng/(startingPoint.getDist(sun)*startingPoint.getDist(sun)))/2-k/startingPoint.getDist(sun); e = Math.sqrt(1 + 2*Energy*MomAng*MomAng/(k*k)); // System.out.println("angolo =" + angle); // anglei and Anglei are the two possible angles determined by // the starting position & starting speed anglei = angle - Math.abs(Math.acos((startingPoint.getDist(sun)-MomAng*MomAng/k)/(startingPoint.getDist(sun)*e))); Anglei = angle + Math.abs(Math.acos((startingPoint.getDist(sun)-MomAng*MomAng/k)/(startingPoint.getDist(sun)*e))); // half length of the bigger ellipse axis dist = startingPoint.getDist(sun)*(1-e*Math.cos(angle-anglei))/(1-e*e); orbita = new Orbita(img,Color.green,div,e,dist,anglei,Anglei,vi,angle,Rversd,Fversd,sun); orbita.Draw(); startingPoint.Draw(); sun.Draw(); Fversd.Draw(); Rversd.Draw(); rePrintBackground(img); img.drawString("" + lastThreeDigits(e),posx+posDx,posy); img.drawString("" + lastThreeDigits(dist),posx+posDx,posy+posz); img.drawString("" + lastThreeDigits(dist*(1-e*e)),posx+posDx,posy+2*posz); img.drawString("" + lastThreeDigits((double)vi.getDx()),posx+posDx,posy+3*posz); img.drawString("" + lastThreeDigits((double)vi.getDy()),posx+posDx,posy+4*posz); img.drawString("" + -lastThreeDigits(MomAng),posx+posDx,posy+5*posz); img.drawString("" + lastThreeDigits(( RadInSp*RadInSp+MomAng*MomAng/(startingPoint.getDist(sun)*startingPoint.getDist(sun)))/2),posx+posDX,posy+6*posz); img.drawString("" + -lastThreeDigits(k/startingPoint.getDist(sun)),posDX+posx,posy+7*posz); img.drawString("" + lastThreeDigits(Energy),posx+posDX,posy+8*posz); } return true; } public boolean mouseDrag(Event evt, int x, int y){ if( x>0 && x<420 && y>40 && y<400 ){ if(orbita != null){ orbita.Clear(); } vi.Clear(); vi.setLastCoordinates(x,y); vi.Draw(); Rvers = new UniVettore(0,0, startingPoint.getX(sun),startingPoint.getY(sun)); Fvers = new UniVettore(0,0,-startingPoint.getY(sun),startingPoint.getX(sun)); RadInSp = Rvers.getDx()*vi.getDx() + Rvers.getDy()*vi.getDy(); AngInSp = (Fvers.getDx()*vi.getDx() + Fvers.getDy()*vi.getDy())/startingPoint.getDist(sun); MomAng = startingPoint.getDist(sun)*startingPoint.getDist(sun)*AngInSp; Energy = (RadInSp*RadInSp+MomAng*MomAng/(startingPoint.getDist(sun)*startingPoint.getDist(sun)))/2-k/startingPoint.getDist(sun); e = Math.sqrt(1 + 2*Energy*MomAng*MomAng/(k*k)); // System.out.println("angolo =" + angle); // anglei and Anglei are the two possible angles determined by // the starting position & starting speed anglei = angle - Math.abs(Math.acos((startingPoint.getDist(sun)-MomAng*MomAng/k)/(startingPoint.getDist(sun)*e))); Anglei = angle + Math.abs(Math.acos((startingPoint.getDist(sun)-MomAng*MomAng/k)/(startingPoint.getDist(sun)*e))); // half length of the bigger ellipse axis dist = startingPoint.getDist(sun)*(1-e*Math.cos(angle-anglei))/(1-e*e); orbita = new Orbita(img,Color.green,div,e,dist,anglei,Anglei,vi,angle,Rversd,Fversd,sun); orbita.Draw(); startingPoint.Draw(); sun.Draw(); Fversd.Draw(); Rversd.Draw(); rePrintBackground(img); img.drawString("" + lastThreeDigits(e),posx+posDx,posy); img.drawString("" + lastThreeDigits(dist),posx+posDx,posy+posz); img.drawString("" + lastThreeDigits(dist*(1-e*e)),posx+posDx,posy+2*posz); img.drawString("" + lastThreeDigits((double)vi.getDx()),posx+posDx,posy+3*posz); img.drawString("" + lastThreeDigits((double)vi.getDy()),posx+posDx,posy+4*posz); img.drawString("" + -lastThreeDigits(MomAng),posx+posDx,posy+5*posz); img.drawString("" + lastThreeDigits(( RadInSp*RadInSp+MomAng*MomAng/(startingPoint.getDist(sun)*startingPoint.getDist(sun)))/2),posx+posDX,posy+6*posz); img.drawString("" + -lastThreeDigits(k/startingPoint.getDist(sun)),posDX+posx,posy+7*posz); img.drawString("" + lastThreeDigits(Energy),posx+posDX,posy+8*posz); return true; } return false; } public final synchronized void update(Graphics g) { String str; int i; // Set up offscreen buffer if(screen == null) { screen = createImage(580,400); img = screen.getGraphics(); } // Only want to draw this once if(draw_t){ // Fill black background img.setColor(Color.black); img.fillRect(0,40,419,399); // Set the background Font img.setFont(TimesRoman); img.setColor(Color.gray); img.fillRect(0,0,579,39); // Fill white background img.setColor(Color.white); img.fillRect(420,40,579,399); img.setColor(Color.blue); img.drawString("e =",posx,posy); img.drawString("a =",posx,posy+posz); img.drawString("b =",posx,posy+2*posz); img.drawString("Vx =",posx,posy+3*posz); img.drawString("Vy =",posx,posy+4*posz); img.drawString("L =",posx,posy+5*posz); img.drawString("En. Cin. =",posx,posy+6*posz); img.drawString("En. Pot. =",posx,posy+7*posz); img.drawString("En. Tot. =",posx,posy+8*posz); //Draw sun sun = new Satellite(img,Color.yellow,210,180); sun.Draw(); // get background for first draw oldbackg.drawImage(screen,-oldx-sun.getX()-5,-oldy-sun.getY()-5,null); draw_t=false; } if( runningFlag == 1 ){ // Replace Old background img.drawImage(oldback,oldx+sun.getX()+5,oldy+sun.getY()+5,null); // get new background oldbackg.drawImage(screen,-px-sun.getX()-5,-py-sun.getY()-5,null); // Keep track of previous x,y coordinates oldx=px; oldy=py; // Draw Satelite px += sun.getX()+5; py += sun.getY()+5; if(startingPoint==null){startingPoint=new Satellite(img,Color.pink,px,py);} startingPoint.setCoordinates(px,py); startingPoint.Draw(); orbita = new Orbita(img,Color.green,div,e,dist,anglei,Anglei,vi,angle,Rversd,Fversd,sun); orbita.Draw(); rePrintBackground(img); img.drawString("" + lastThreeDigits(e),posx+posDx,posy); img.drawString("" + lastThreeDigits(dist),posx+posDx,posy+posz); img.drawString("" + lastThreeDigits(dist*(1-e*e)),posx+posDx,posy+2*posz); img.drawString("" + lastThreeDigits((double)vi.getDx()),posx+posDx,posy+3*posz); img.drawString("" + lastThreeDigits((double)vi.getDy()),posx+posDx,posy+4*posz); img.drawString("" + -lastThreeDigits(MomAng),posx+posDx,posy+5*posz); img.drawString("" + lastThreeDigits(( RadInSp*RadInSp+MomAng*MomAng/(startingPoint.getDist(sun)*startingPoint.getDist(sun)))/2),posx+posDX,posy+6*posz); img.drawString("" + -lastThreeDigits(k/startingPoint.getDist(sun)),posDX+posx,posy+7*posz); img.drawString("" + lastThreeDigits(Energy),posx+posDX,posy+8*posz); } g.drawImage(screen,0,0,null); } public boolean action(Event event,Object arg){ if(event.target == startbutton){ draw_t = true; rePrintBackground(img); startingPoint.Clear(); vi.Clear(); Rversd.Clear(); Fversd.Clear(); runningFlag = 1; return true; } else if (event.target == stopbutton){ runningFlag = 0; return true; } else return action(event,arg); } public int segno(double pippo){ if(pippo > 0){ return 1; } else if(pippo < 0){return -1; } else{ return 0; } } public double Traiettoria(Vettore vi,double dist,double e,Vettore Rversd,Vettore Fversd,double angle,double anglei,double Anglei){ if( ( angle <= Math.PI/2 ) || ( angle >= 3*Math.PI/2 ) ){ if( (vi.getDx()*Fversd.getDx()+vi.getDy()*Fversd.getDy())*(vi.getDx()*Rversd.getDx()+vi.getDy()*Rversd.getDy()) < 0 ){ return (dist*(1-e*e)/(1-e*Math.cos(angle-anglei))); } else{ return (dist*(1-e*e)/(1-e*Math.cos(angle-Anglei))); } } else{ if( (vi.getDx()*Fversd.getDx()+vi.getDy()*Fversd.getDy())*(vi.getDx()*Rversd.getDx()+vi.getDy()*Rversd.getDy()) < 0 ){ return (dist*(1-e*e)/(1-e*Math.cos(angle-anglei))); } else{ return (dist*(1-e*e)/(1-e*Math.cos(angle - Anglei))); } } } public double lastThreeDigits(double pippo){ return ((double)((int)(pippo*1000)))/1000; } public void rePrintBackground(Graphics img){ img.setColor(Color.gray); img.fillRect(0,0,579,39); img.setColor(Color.white); img.fillRect(420,40,579,399); img.setColor(Color.blue); img.drawString("e =",posx,posy); img.drawString("a =",posx,posy+posz); img.drawString("b =",posx,posy+2*posz); img.drawString("Vx =",posx,posy+3*posz); img.drawString("Vy =",posx,posy+4*posz); img.drawString("L =",posx,posy+5*posz); img.drawString("En. Cin. =",posx,posy+6*posz); img.drawString("En. Pot. =",posx,posy+7*posz); img.drawString("En. Tot. =",posx,posy+8*posz); } }