Jeronimus

import javax.swing.*;
import java.util.ArrayList;
import java.awt.*;
import java.awt.image.BufferStrategy;
import static java.lang.Math.*;
import java.awt.event.*;
import java.awt.image.BufferedImage;

class Spacetime {

  public static void main(String[] args) {

    MainClass mainClass = new MainClass();
    mainClass.start();

  }
}


class MainClass {

  public MainClass() {

  }

  public void start(){

    createFrameAndCanvases();
    generateEvents();
    generateEvents_p();

    render();
    jFrame.paintComponents(g2DjFrame);
    jFrame.repaint();

    mainLoop();
  }


  public void mainLoop() {


    do{
      updateState();
      render();
      try{Thread.sleep(20);} catch (Exception e){};
    } while(true);
  }

  int stage=1;
  boolean deletePaths=false;

  public void updateState(){

    here:

      if(!lock) {

      if (deletePaths==true){
        g2Dimg.setBackground(new Color(0,0,0,0));
        g2Dimg.clearRect(0,0,501,501);
        deletePaths=false;
        if (stage<6){stage+=1;}
      }

      if (stage==1){

        if ((round(v_rel*10000)/10000.0)<0.5) { accelerate();
        } else {
          lock=true;
          deletePaths=true;
          break here;
        }
      }

      if (stage==2) {

        if ((round(timePassed*10000)/10000.0)<10){letSomeTimePass();
        } else {
          turnAroundTime = timePassed;
          turnAroundPosition = v_rel*timePassed;
          lock=true;
          deletePaths=true;
          break here;
        }
      }

      if (stage==3) {

        if ((round(v_rel*10000)/10000.0)>0) {deccelerate();
        } else {
          lock=true;
          deletePaths=true;
          break here;
        }
      }


      if (stage==4) {

        if ((round(v_rel*10000)/10000.0)>-0.5) {deccelerate();
        } else {
          lock=true;
          deletePaths=true;
          break here;
        }
      }


      if (stage==5) {

        if((round(timePassed*10000)/10000.0)<20) {letSomeTimePass();
        } else {
          lock=true;
          deletePaths=true;
          break here;
        }
      }

      if (stage==6) {

        if ((round(v_rel*10000)/10000.0)<0) {accelerate();
        } else {
          lock=true;
          deletePaths=true;
          break here;
        }
      }
    }
  }


  public void accelerate() {
    v_rel+=0.002;
  }

  public void deccelerate() {
    v_rel-=0.002;
  }


  public void letSomeTimePass() {
    timePassed +=0.02;
  }


  public void render(){

    g2Dcanvas1 = (Graphics2D) strategyCanvas1.getDrawGraphics();
    g2Dcanvas2 = (Graphics2D) strategyCanvas2.getDrawGraphics();
    g2DjFrame = (Graphics2D) strategyJFrame.getDrawGraphics();

    g2Dcanvas1.setColor(backgroundColor);
    g2Dcanvas2.setColor(backgroundColor);
    g2DjFrame.setColor(backgroundColor);

    g2Dcanvas1.fillRect(0,0,501,501);
    g2Dcanvas2.fillRect(0,0,501,501);
    g2DjFrame.fillRect(0,0,1280,720);

    g2Dcanvas1.setColor(Color.WHITE);
    g2Dcanvas1.fillOval((int)(traveller_x*25-10+251),(int)(traveller_t*25-10+251),20,20);

    g2Dcanvas2.setColor(Color.BLUE);
    g2Dcanvas2.fillOval((int)(not_traveller_x_p*25-10+251),(int)(not_traveller_t_p*25-10+251),20,20);

    g2Dcanvas1.setColor(Color.BLUE);
    g2Dcanvas1.fillOval((int)(xPos*25-10+251),(int)(-tPos*25-10+251),20,20);

    if (showPaths) {
      g2Dcanvas2.drawImage(bufferedImage,0,0,501,501,null);}


    g2Dcanvas1.setStroke(new BasicStroke(2));
    g2Dcanvas2.setStroke(new BasicStroke(2));
    plotLightbeams();

    g2Dcanvas1.setStroke(new BasicStroke(1));
    g2Dcanvas2.setStroke(new BasicStroke(1));
    plotDiagrams();

    g2Dcanvas1.setStroke(new BasicStroke(3));
    g2Dcanvas2.setStroke(new BasicStroke(3));
    plotEvents();


    jFrame.paintComponents(g2DjFrame);

    g2DjFrame.setColor(Color.BLACK);
    g2DjFrame.setFont(stringFont3);

    g2DjFrame.drawString("Vrel "+(Double.toString(round(v_rel*10000)/10000.0)+"c"),610,100);
    g2DjFrame.setColor(Color.BLACK);
    g2DjFrame.drawString("stage "+stage,615,150);

    g2DjFrame.setColor(Color.BLUE);
    g2DjFrame.drawString("Observer clock count "+(Double.toString(round(timePassed*10000)/10000.0))+"s",50,570);
    g2DjFrame.drawString("x-Pos / t-Pos: 0ls / 0s",50,600);
    g2DjFrame.setColor(Color.WHITE);
    g2DjFrame.drawString("White clock count "+(Double.toString(round(timePassed_p*10000)/10000.0))+"s",330,570);
    g2DjFrame.drawString("x Position "+(Double.toString(round(traveller_x*10000)/10000.0))+"ls",330,600);
    g2DjFrame.drawString("t Position 0s",330,620);

    g2DjFrame.setColor(Color.WHITE);;
    g2DjFrame.drawString("Observer clock count "+(Double.toString(round(timePassed_p*10000)/10000.0))+"s",700,570);
    g2DjFrame.drawString("x-Pos / t-Pos: 0ls / 0s ",700,600);
    g2DjFrame.setColor(Color.BLUE);
    g2DjFrame.drawString("Blue clock count "+(Double.toString(round(clockTime*10000)/10000.0))+"s",1000,570);
    g2DjFrame.drawString("x Position "+(Double.toString(round(not_traveller_x_p*10000)/10000.0))+"ls",1000,600);
    g2DjFrame.drawString("t Position 0s",1000,620);

    g2DjFrame.drawString("Blue clock count "+(Double.toString(round(clockTime*10000)/10000.0))+"s",50,640);
    g2DjFrame.drawString("x Position 0ls",50,670);
    g2DjFrame.drawString("t Position "+(Double.toString(round(tPos*10000)/10000.0))+"s",50,690);


    strategyCanvas2.show();
    strategyCanvas1.show();
    strategyJFrame.show();

    g2Dcanvas1.dispose();
    g2Dcanvas2.dispose();
    g2DjFrame.dispose();
  }


  public void plotLightbeams() {

    g2Dcanvas1.setColor(Color.YELLOW);
    g2Dcanvas2.setColor(Color.YELLOW);

    g2Dcanvas1.drawLine(0,0,501,501);
    g2Dcanvas1.drawLine(0,501,501,0);

    g2Dcanvas2.drawLine(0,0,501,501);
    g2Dcanvas2.drawLine(0,501,501,0);
  }


  public void plotEvents( ){

    g2Dcanvas1.setFont(stringFont);
    g2Dcanvas2.setFont(stringFont);

    max_gamma = 1/(sqrt(1-pow(0.5,2)));
    temporary_gamma = 1/(sqrt(1-pow(v_rel,2)));

    timePassed_p = timePassed/max_gamma;


    if (stage==1 || stage == 2 ) { traveller_x = v_rel*timePassed; clockTime = timePassed_p/max_gamma;}

    if (stage==3 || stage==4 || stage==5) { traveller_x = v_rel*(timePassed - turnAroundTime) + turnAroundPosition;}

    if (stage==2) { not_traveller_x_p = - v_rel*timePassed_p; rest_length =- v_rel*timePassed_p*max_gamma;  }

    if (stage==3 || stage==4) {

      not_traveller_x_p = rest_length/temporary_gamma;
      turnAroundPosition_p = not_traveller_x_p;
      turnAroundTime_p = timePassed_p;

    }

    if (stage==5) {      not_traveller_x_p = -v_rel*(timePassed_p - turnAroundTime_p) + turnAroundPosition_p;}


    xPos = 0;
    tPos = temporary_gamma*v_rel*not_traveller_x_p;

    clockTime = tPos + timePassed;

    for (int i=0; i<eventsArraylist.size();i++){

      x=eventsArraylist.get(i).xPosInLightSeconds;
      t=eventsArraylist.get(i).timeInSeconds-timePassed;

      clockCounter = eventsArraylist.get(i).clockCounter;


      x_p = temporary_gamma*(x-traveller_x - v_rel * t);
      t_p = temporary_gamma*(t - (v_rel*(x-traveller_x)));

      if ((x<11 && x >-11) && (t <11 && t>-11)){
        g2Dcanvas1.setColor(Color.BLACK);
        if (x==5 || x==-5) { g2Dcanvas1.setColor(Color.GREEN);}
        if (x==0 ) { g2Dcanvas1.setColor(Color.BLUE);}

        g2Dcanvas1.drawString(Integer.toString((int)clockCounter),(int)(x*25+251-4),(int)(251+4-t*25));

        g2Dimg.setColor(Color.BLACK);
        if (x==5 || x==-5) { g2Dcanvas2.setColor(Color.GREEN); g2Dimg.setColor(Color.GREEN);}
        if (x==0 ) { g2Dcanvas2.setColor(Color.BLUE); g2Dimg.setColor(Color.BLUE);}


        g2Dcanvas2.drawString(Integer.toString((int)clockCounter),(int)(x_p*25+251-4),(int)(251+4-t_p*25));
        g2Dcanvas2.setColor(Color.BLACK);

        g2Dimg.setStroke(new BasicStroke(2));
        g2Dimg.drawLine((int)(x_p*25+251),(int)(251-t_p*25),(int)(x_p*25+251),(int)(251-t_p*25));
      }
    }

    for (int i=0; i<events_pArraylist.size();i++){

      x=events_pArraylist.get(i).xPosInLightSeconds;
      t=events_pArraylist.get(i).timeInSeconds-timePassed_p;

      if ((x<11 && x >-11) && (t <11 && t>-11) && (showWorldline==true)){
        clockCounter = events_pArraylist.get(i).clockCounter;

        g2Dcanvas2.setColor(Color.WHITE);
        g2Dcanvas2.drawString(Integer.toString((int)clockCounter),(int)(x*25+251-4),(int)(251+4-t*25));

        x_p = temporary_gamma*(x + v_rel * t)+traveller_x;
        t_p = temporary_gamma*(t + v_rel*x);

        g2Dcanvas1.setColor(Color.WHITE);
        g2Dcanvas1.drawString(Integer.toString((int)clockCounter),(int)(x_p*25+251-4),(int)(251+4-t_p*25));
      }
    }
  }


  public void createFrameAndCanvases(){

    jFrame = new JFrame();
    jFrame.setLayout(null);
    jFrame.setSize(1280,720);
    jFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    jFrame.getContentPane().setBackground(new Color(110,110,111));
    jFrame.setResizable(true);
    jFrame.setIgnoreRepaint(true);

    button1 = new JButton("start/stop");
    button1.setBounds(500,580,100,100);
    button1.addActionListener(actionListener);
    button1.setActionCommand("start/stop");
    jFrame.add(button1);

    button2 = new JButton("reset");
    button2.setBounds(620,580,100,100);
    button2.addActionListener(actionListener);
    button2.setActionCommand("reset");
    button2.setVisible(true);
    jFrame.add(button2);

    canvas1 = new Canvas();
    canvas1.setSize(501,501);
    canvas1.setLocation(75,0);
    canvas1.setIgnoreRepaint(true);
    canvas1.setBackground(new Color(222,222,222));
    jFrame.add(canvas1);

    canvas2 = new Canvas();
    canvas2.setSize(501,501);
    canvas2.setLocation(1280-501-75,0);
    canvas2.setIgnoreRepaint(true);
    canvas2.setBackground(new Color(222,222,222));
    jFrame.add(canvas2);

    checkBox = new JCheckBox("show/hide paths",false);
    checkBox.addActionListener(actionListener);
    checkBox.setActionCommand("show/hide paths");
    checkBox.setBounds(750,580,200,20);
    jFrame.add(checkBox);

    checkBox2 = new JCheckBox("white clock (est.)worldline",true);
    checkBox2.addActionListener(actionListener);
    checkBox2.setActionCommand("white clock (est.)worldline");
    checkBox2.setBounds(750,600,200,20);
    jFrame.add(checkBox2);


    jFrame.setVisible(true);

    jFrame.createBufferStrategy(2);
    canvas1.createBufferStrategy(2);
    canvas2.createBufferStrategy(2);

    strategyCanvas1 = canvas1.getBufferStrategy();
    strategyCanvas2 = canvas2.getBufferStrategy();

    strategyJFrame = jFrame.getBufferStrategy();

    g2DjFrame = (Graphics2D) strategyJFrame.getDrawGraphics();

    g2Dcanvas1 = (Graphics2D) strategyCanvas1.getDrawGraphics();
    g2Dcanvas2 = (Graphics2D) strategyCanvas2.getDrawGraphics();
  }


  public void plotDiagrams() {

    g2Dcanvas1.setFont(stringFont2);
    g2Dcanvas2.setFont(stringFont2);

    g2Dcanvas1.setColor(Color.BLACK);
    g2Dcanvas2.setColor(Color.BLACK);

    g2Dcanvas1.drawLine(0,250,500,250);
    g2Dcanvas1.drawLine(250,0,250,500);

    g2Dcanvas2.drawLine(0,250,500,250);
    g2Dcanvas2.drawLine(250,0,250,500);

    int x,t;
    for (x=0; x<21;x++){
      if (x!=10) {
        g2Dcanvas1.drawLine(x*(500/20),245, x*(500/20),255);
        g2Dcanvas1.drawString(Integer.toString(x-10),x*(500/20)-5,268);
        g2Dcanvas2.drawLine(x*(500/20),245, x*(500/20),255);
        g2Dcanvas2.drawString(Integer.toString(x-10),x*(500/20)-5,268);
      }
    }

    for (t=0; t<21;t++){
      if (t!=10) {
        g2Dcanvas1.drawLine(245,t*(500/20), 255,t*(500/20));
        g2Dcanvas1.drawString(Integer.toString(10-t),258,t*(500/20)+5);
        g2Dcanvas2.drawLine(245,t*(500/20), 255,t*(500/20));
        g2Dcanvas2.drawString(Integer.toString(10-t),258,t*(500/20)+5);
      }
    }
  }


  public void generateEvents(){
    int i=0;
    int x,t,clockCounter;
    for (x=-40; x<41;x++){
      for (t=-40; t<41;t++){
        clockCounter = t;
        eventsArraylist.add( new Event(x,t,clockCounter));

      }
    }

  }

  public void generateEvents_p(){
    int i=0;
    int x,t,clockCounter;
    x=0;
    for (t=-40; t<41;t++){
      clockCounter = t;
      events_pArraylist.add( new Event_p(x,t,clockCounter));
    }
  }


  class Event_p {

    double xPosInLightSeconds;
    double timeInSeconds;
    double clockCounter;

    public Event_p(int x, int t, int cc) {

      xPosInLightSeconds = x;
      timeInSeconds = t;
      clockCounter = cc;

    }
  }


  class Event {

    double xPosInLightSeconds;
    double timeInSeconds;
    double clockCounter;

    public Event(int x, int t, int cc) {

      xPosInLightSeconds = x;
      timeInSeconds = t;
      clockCounter = cc;

    }
  }

  public void resetAll(){

    v_rel=0;
    timePassed=0;
    not_traveller_x_p = 0;
    traveller_x=0;
    deletePaths=false;
    stage = 1;

    g2Dimg.setBackground(new Color(0,0,0,0));
    g2Dimg.clearRect(0,0,501,501);

    lock = true;
  }


  JFrame jFrame;
  Canvas canvas1,canvas2;

  double turnAroundTime, turnAroundPosition;
  double traveller_x,traveller_t, not_traveller_x_p, not_traveller_t_p;
  double x,t,x_p,t_p,clockCounter;
  double rest_length;
  double timePassed_p, turnAroundPosition_p,turnAroundTime_p;
  double max_gamma, clockTime;
  double xPos, tPos;

  boolean lock=true, showPaths=false, showWorldline=true;

  BufferedImage bufferedImage = new BufferedImage(501, 501,BufferedImage.TYPE_INT_ARGB);

  Color backgroundColor = new Color(211,222,222);
  BufferStrategy strategyCanvas1,strategyCanvas2,strategyJFrame;
  Graphics2D g2Dcanvas1, g2Dcanvas2, g2DjFrame, g2Dimg = bufferedImage.createGraphics();;

  JButton button1,button2;
  JCheckBox checkBox, checkBox2;

  ArrayList<Event> eventsArraylist = new ArrayList<Event>();
  ArrayList<Event_p> events_pArraylist = new ArrayList<Event_p>();

  double temporary_gamma,v_rel,timePassed;

  Font stringFont = new Font( "SansSerif", Font.BOLD, 14 );
  Font stringFont2 = new Font( "SansSerif", Font.PLAIN, 10 );
  Font stringFont3 = new Font( "SansSerif", Font.PLAIN, 20 );

  ActionListener actionListener = new ActionListener() {

    public void actionPerformed(ActionEvent e) {
      String str=e.getActionCommand();

      if (str.equals("show/hide paths")) {

        if (showPaths) {showPaths=false;} else {showPaths=true;};
      }

      if (str.equals("white clock (est.)worldline")) {

        if (showWorldline) {showWorldline=false;} else {showWorldline=true;};
      }

      if (str.equals("reset")) {

        resetAll();
      }

      if (str.equals("start/stop")){
        if (lock){lock=false;} else {lock=true;};
      }
    }
  };
}