solar_system_n_(20)_planets_an_time, Pascal

solar_system_n_(20)_planets_an_time

uses GraphABC;

const
  n = 20; // количество планет
  t = 0.00001;// шаг по времени

type
  velocity = record // скорость i-го тела в начале, в конце и в середине интервала
    x: array [1..n, 1..3] of real; 
    y: array [1..n, 1..3] of real;
  end;
  
  acceleration = record // ускорение i-го тела
    x: array [1..n] of real;
    y: array [1..n] of real;
  end;

var
  x: array [1..n] of real; // x-координата i-го тела
  y: array [1..n] of real; // y-координата i-го тела
  r: array [1..n, 1..n] of real; // расстояние между i-ым и j-ым телами 
  m: array [1..n] of real;// масса i-го тела

var
  v: velocity;
  a: acceleration;
  flag: integer;// определяет через сколько интервалов t выводить изображение

var
  i, j: integer;

begin
  flag := 0;
  // вводим начальные условия для первого тела
  m[1] := 3;
  x[1] := 0;         y[1] := 0;
  v.x[1, 1] := 0.0;   v.y[1, 1] := 0.0;
  v.x[1, 2] := 0.0;   v.y[1, 2] := 0;
  
  v.x[1, 3] := 0.0;   v.y[1, 3] := 0.5 * (v.y[1, 1] + v.y[1, 2]);
  
  // вводим начальные условия для второго тела
  m[2] := 0.000001;
  x[2] := 0.5;          y[2] := 0;
  v.x[2, 1] := 0.0;   v.y[2, 1] := 0.0;
  v.x[2, 2] := 0;     v.y[2, 2] := 6;
  
  v.x[2, 3] := 0.0;   v.y[2, 3] := 0.5 * (v.y[2, 1] + v.y[2, 2]);
  
  // вводим начальные условия для третьего тела
  m[3] := 0.000001;
  x[3] := 1;          y[3] := 0;
  v.x[3, 1] := 0.0;   v.y[3, 1] := 0.0;
  v.x[3, 2] := 0;     v.y[3, 2] := 4;
  
  v.x[3, 3] := 0.0;   v.y[3, 3] := 0.5 * (v.y[3, 1] + v.y[3, 2]);
  
  // вводим начальные условия для четвёртого тела
  m[4] := 0.000001;
  x[4] := -2;          y[4] := 0;
  v.x[4, 1] := 0.0;   v.y[4, 1] := 0.0;
  v.x[4, 2] := 0;     v.y[4, 2] := -2;
  
  v.x[4, 3] := 0.0;   v.y[4, 3] := 0.5 * (v.y[4, 1] + v.y[4, 2]);
  
  // вводим начальные условия для пятого тела
  m[5] := 0.000001;
  x[5] := 4;          y[5] := 0;
  v.x[5, 1] := 0.0;   v.y[5, 1] := 0.0;
  v.x[5, 2] := 0;     v.y[5, 2] := 1;
  
  v.x[5, 3] := 0.0;   v.y[5, 3] := 0.5 * (v.y[5, 1] + v.y[5, 2]);
  
  // вводим начальные условия для шестого тела
  m[6] := 0.01;
  x[6] := -4;          y[6] := 0;
  v.x[6, 1] := 0.0;   v.y[6, 1] := 0.0;
  v.x[6, 2] := 0;     v.y[6, 2] := -1.5;
  
  v.x[6, 3] := 0.0;   v.y[6, 3] := 0.5 * (v.y[6, 1] + v.y[6, 2]);
  
  // вводим начальные условия для остальных n тел
  for i := 7 to n do
  begin
    m[i] := 0.000001;
    x[i] := -4 + random;          y[i] := 0;
    v.x[i, 1] := 0.0;   v.y[i, 1] := 0.0;
    v.x[i, 2] := 0;     v.y[i, 2] := -1 - random(2);
    
    v.x[i, 3] := 0.0;   v.y[i, 3] := 0.5 * (v.y[i, 1] + v.y[i, 2]);
  end;
  
   // вводим начальные условия для первого тела
  m[1] := 3;
  x[1] := 0;          y[1] := 0;
  v.x[1, 1] := 0.0;   v.y[1, 1] := 0.0;
  v.x[1, 2] := 0.0;   v.y[1, 2] := 0;
  
  v.x[1, 3] := 0.0;   v.y[1, 3] := 0.5 * (v.y[1, 1] + v.y[1, 2]);
  
  for i := 1 to n do
  begin
    a.x[i] := 0;
    a.y[i] := 0;
  end;
  
  // задаём начальные расстояния между телами
  
  for i := 1 to n do
    for j := 1 to n do
      if i <> j then
      begin
        r[i, j] := -sqrt(sqr(x[i] - x[j]) + sqr(y[i] - y[j])) ** 3;
        a.x[i] := a.x[i] + m[j] * (x[i] - x[j]) / r[i, j];
        a.y[i] := a.y[i] + m[j] * (y[i] - y[j]) / r[i, j];
      end;
  
  SetWindowTop(10);
  SetWindowLeft(10);
  SetWindowSize(1000, 1000);
  
  while x[1] < 10000 do
  begin
    for i := 1 to n do
    begin
      
      x[i] := x[i] + t * v.x[i, 3];
      y[i] := y[i] + t * v.y[i, 3];
      
      v.x[i, 1] := v.x[i, 1] + t * a.x[i];
      v.y[i, 1] := v.y[i, 1] + t * a.y[i];
      
      v.x[i, 2] := v.x[i, 2] + (t + t ) * a.x[i];
      v.y[i, 2] := v.y[i, 2] + (t + t ) * a.y[i];
      
      v.x[i, 3] := 0.5 * (v.x[i, 1] + v.x[i, 2] );
      v.y[i, 3] := 0.5 * (v.y[i, 1] + v.y[i, 2] );
    end;
    
    for i := 1 to n do
    begin
      a.x[i] := 0;
      a.y[i] := 0;  
      for j :=  1 to n do
        if i <> j then
        begin
          r[i, j] := -sqrt(sqr(x[i] - x[j]) + sqr(y[i] - y[j])) ** 3;
          a.x[i] := a.x[i] + m[j] * (x[i] - x[j]) / r[i, j];
          a.y[i] := a.y[i] + m[j] * (y[i] - y[j]) / r[i, j];
        end;
    end;    
    if flag mod 500  = 0 then // рисуем через 100 временных циклов циклов
    begin
      
      ClearWindow;
      LockDrawing;
      
      line(100, 500, 800, 500);
      line(500, 100, 500, 800);
      
      for i := 1 to n do
      begin
        if m[i] < 0.01 then 
          circle(round(500 + 100 * x[i]), round(500 + 100 * y[i]), round( 2 ) )
        else if m[i] < 0.1 then
          circle(round(500 + 100 * x[i]), round(500 + 100 * y[i]), round( 4 ) )
        else 
          circle(round(500 + 100 * x[i]), round(500 + 100 * y[i]), round( m[i] * 10 ) );
        
      end;
      for i := 1 to n - 1 do
        for j := i + 1 to n do
        begin
          //line(round(500 + 100 * x[i]), round(500 + 100 * y[i]), round(500 + 100 * x[j]), round(500 + 100 * y[j]));
        end;
      
      
      
      // circle(round(500 + 100 * (m[1]*x[1]+m[2]*x[2]+m[3]*x[3])/(m[1]+m[2]+m[3])), round(500 + 100 * (m[1]*y[1]+m[2]*y[2]+m[3]*y[3])/(m[1]+m[2]+m[3])), round( 3 ) );
      
      Redraw;
      
      if random(101) = 5 then 
      begin
        // m[1] := 1.05 * m[1];
        // m[2] := 0.95 * m[2];
      end;
    end;
    if flag < 1000 then flag := flag + 1 else flag := 0;
  end;
  
end.


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