program Model_At;
  uses Crt, Graph;
  const Ra=100;                        {ðàäèóñ àòîìà}
            Rc=10;                     {ðàäèóñ ÿäðà}
            Re=4;                      {ðàäèóñ ýëåêòðîíà}
            k=0.5;                     {êîýôôèöèåíò ñæàòèÿ îðáèò ýëåêòðîíîâ}
            Dr=30;                     {ïàðàìåòð èçìåíåíèÿ êîîðäèíàò ýëåêòðîíà}
            Step1=0.2;                 {øàã èçìåíåíèÿ ïîëîæåíèÿ ýëåêòðîíà}
            Step=100;                  {âðåìÿ çàäåðæêè – ñêîðîñòü äâèæåíèÿ ýëåêòðîíîâ}
   var cx, cy, y, y1, y2, x, x1, x2, x3,y3:integer;
          I, I1, I2, I3: real; gd, gm: integer;
begin
  clrscr;
  gd:=detect;
   initgraph(gd, gm, '');               {îïðåäåëÿåì äðàéâåð ãðàôèêè}
   SetTextStyle(0, 0, 2);               { çàäàåì ñòèëü îòîáðàæåíèÿ òåêñòà }
   OutTextXY(200, 30, 'Model atoma');   {âèâîäèì òåêñò}
   cx:=GetMaxX div 2;                   {îïðåäåëèòü öåíòð ýêðàíà- ïîëîæåíèå ÿäðà ïî îñè Õ}
   cy:=GetMaxY div 2;                   {îïðåäåëèòü öåíòð ýêðàíà- ïîëîæåíèå ÿäðà ïî îñè Ó}
   PieSlice(cx, cy, 0, 360, Rc);        {íàðèñîâàòü ÿäðî àòîìà}
   SetColor(Red);                       {çàäàåì öâåò äëÿ ðèñîâàíèÿ}
   SetLineStyle(0, 0, 3);               {çàäàåì ñòèëü äëÿ ëèíèé}
   Line(cx-7, cy, cx+7, cy);            {ðèñóåì äâå ëèíè(êðåñòèê â íóòðè àòîìà}
   Line(cx, cy-5, cx, cy+5);
   SetLineStyle(0,0,1);
   SetFillStyle(1,1);
   I:=Pi/4;                            {çàäàòü íà÷àëüíîå ïîëîæåíèå 2 ýëåêòðîíîâ}
   I1:= - Pi/4;
   SetTextStyle(0, 0, 1);
   SetColor(yellow);
   OutTextXY (180, 420,'Dla otmenu nazmute lybuy klavushy');
   While not KeyPressed do             {ïîâòîðÿòü, ïîêà íå íàæàòà ëþáàÿ êëàâèøà }
      Begin                            {îïðåäåëèòü êîîðäèíàòû ýëåêòðîíîâ}
         x:=Round(Ra*cos(I)) +cx;   Y:= Round (Ra*sin(I)) +cy;
       x1:= Round(Ra*cos(I1)) +cx; y1:= Round (Ra*sin(I1)) +cy;

         SetColor(1);                   {çàäàåì öâåò ðèñîâàíèÿ}
         Circle(x, y, Re);              { ðèñóåì êîëî - åëåêòðîí}
        PutPixel(x, y, 2);              {ñòàâèò òî÷êó}
        Circle(x1, y1, Re);
        PutPixel(x1, y1, 2);

        Delay(Step);                    {çàäåðæêà åëåêòðîíà, èíà÷å ìè èõ íå óâèäèì}

        SetColor(0);
        Circle(x, y, Re);
        PutPixel(x, y, 2);
        Circle(x1, y1, Re);
        PutPixel(x1, y1, 2);            {çàäàòü èçìåíåíèå ïîëîæåíèÿ ýëåêòðîíîâ}
        I:=I + Step1;                   {óâåëè÷èâàåì êðîê äëÿ îòîáðàæåíèÿ åëåêòðîíà}
        I1:=I1 - Step1;

      end;                              {êîíåö öèêëà}
   CloseGraph;                          {çàêðèâàåì ãðàô äðàéâåð}
end.