{$N+}
uses crt,
     graph;
var  x1, x2, y1, y2, r,x_, y_, x__, y__,
     bgC, speed1, speed2: integer;
     Gd, Gm : integer;
     choise : integer;
     h, t, i : integer;
     angle1, angle2 : single;
     c, q : char;
     s : string;
procedure draw (x, y, r, c : integer);
begin
  setfillstyle(solidfill, c);
  fillellipse(x, y, r, r);
  Setcolor (c);
  circle (x, y, r);
end;

procedure escape (x, y, r, bgC : integer);
begin
  setfillstyle(solidfill, bgC);
  fillellipse(x, y, r, r);
  Setcolor (bgC);
  circle (x, y, r);

end;

procedure move (var x, y: integer; angle : single; speed : integer);
begin
 x := round(x + speed*cos(angle));
 y := round(y + speed*sin(angle));
end;

function angleX (angle : single):single;
begin
 angleX := (pi - angle);
end;

function angleY (angle : single): single;
begin
 angleY := -angle;
end;

Procedure border1 (var x1, y1 : integer; r1: integer{; speed: integer{; angle : single});
begin
 if (x1 + r1 >= GetMaxX-1) or (x1 - r1 <= 1) then angle1 := angleX(angle1);
 if (y1 + r1 >= GetMaxY-1) or (y1 - r1 <= 1) then angle1 := angleY(angle1);

end;

Procedure border2 (var x2, y2 : integer; r2: integer{; speed: integer{; angle : single});
begin
 if (x2 + r2 >= GetMaxX-1) or (x2 - r2 <= 1) then angle2 := angleX(angle2);
 if (y2 + r2 >= GetMaxY-1) or (y2 - r2 <= 1) then angle2 := angleY(angle2);

end;



function value(const r: integer):real;
begin
 value := 4/3*pi*r*r*r;
end;

procedure after_hit (var speed1, speed2 : integer; var  angle1, angle2 : single);
var m1, m2 : real;
    Vx1, Vy1, Vx2, Vy2 : real;
    t1, t2, t3, t4, t5, t6, t7, t8, t9, t10 : real;
    begin
 m1 := value(r);
 m2 := value(r);
 Vx1 := speed1*cos(angle1);
 Vy1 := speed1*sin(angle1);
 Vx2 := speed2*cos(angle2);
 Vy2 := speed2*sin(angle2);
 t1 :=  m2/(m1*(m2 + m1));
 t2 :=  (Vx1 - Vx2);
 t3 :=  (m1*m1*m2 - m1);
 Vx1 := Vx1 + t1*t2*t3;
 t4 :=  (Vy1 - Vy2);
 Vy1 := Vy1 + t1*t4*t3;
 t5 :=  Vx1*m1 + m2*Vx2;
 t6 :=  m1*m1*Vx1;
 t7 :=  m1*m1*m2*Vx2;
 vx2 := (t5 - t6 + t7)/(m2 + m1);
 t8 :=  Vy1*m1 + m2*Vy2;
 t9 :=  m1*m1*Vy1;
 t10 :=  m1*m1*m2*Vy2;
 vy2 := (t8 - t9 + t10)/(m2 + m1);
 speed1 := round(sqrt(Vx1*Vx1 + Vy1*Vy1));
 Angle1 := Arctan(Vy1/Vx1);
 if abs(Vx1) < 1e - 5 then begin
 Angle1 := pi/2;
 if Vy1 < 0 then Angle1 := - angle1
 end
 else begin
 Angle1 := ArcTan(Vy1/Vx1);
 if Vx1 < 0 then  Angle1 := - angle1
 end;
 speed2 := round(sqrt(Vx2*Vx2 + Vy2*Vy2));
 Angle2 := Arctan(Vy2/Vx2);
 if abs(Vx2) < 1e - 5 then begin
 Angle2 := pi/2;
 if Vy2 < 0 then Angle2 := - angle2
 end
 else begin
 Angle2 := ArcTan(Vy2/Vx2);
 if Vx2 < 0 then  Angle2 := - angle2
 end;
end;


function balls_hit (const r1,r2 : integer; x1,y1,x2,y2 : integer) : boolean;
var
  dist : real;
  t1, t2, t3, t4, t5: real;
begin
  t1 := abs(x2-x1); t2 := sqr(t1);
  t3 := abs(y2-y1); t4 := sqr(t3);
  t5 := t2 + t4;
  dist := sqrt(t5);

  balls_hit := (dist < (r1 + r2));
end;

procedure balls_hit_2;
begin
 if balls_hit(r,r,x1,y1,x2,y2) then  after_hit (speed1, speed2,angle1,angle2);
end;

function Menu(Params: string): integer; var
  Count: integer;
  Strings: array [0 .. 15] of string [127];
  i: integer;
  Ch: char;
  X, Y, H: integer;
begin
  Count := 1;
  Strings[0] := '';
  for i := 1 to Length(Params) do begin
    if Params[i] = #13 then begin
      Inc(Count);
      Strings[Count - 1] := '';
    end else begin
      Strings[Count - 1] := Strings[Count - 1] + Params[i];
    end;
  end;
  SetTextJustify(CenterText, CenterText);
  H := TextHeight('A') + 10;   ClearDevice;
  SetColor(7);
  for i := 0 to Count - 1 do
    OutTextXY(

      GetMaxX div 2,

      GetMaxY div 2 - (Count - 1) * H div 2 - H div 4 + i * H,

      Strings[i]
    );
  i := 0;
  repeat
    SetColor(LightMagenta);
    X := TextWidth(Strings[i]) + 10;
    Y := TextHeight(Strings[i]) + 10;
    Rectangle(GetMaxX div 2 - X div 2,
      GetMaxY div 2 - (Count - 1) * H div 2 + i * H - Y div 2,
      GetMaxX div 2 + X div 2,
      GetMaxY div 2 - (Count - 1) * H div 2 + i * H + Y div 2);
    ch := readkey;
    SetColor(BLACK);
    X := TextWidth(Strings[i]) + 10;
    Y := TextHeight(Strings[i]) + 10;
    Rectangle(GetMaxX div 2 - X div 2,
      GetMaxY div 2 - (Count - 1) * H div 2 + i * H - Y div 2,
      GetMaxX div 2 + X div 2,
      GetMaxY div 2 - (Count - 1) * H div 2 + i * H + Y div 2);
    case ch of
      #0: case ReadKey of
        #72: begin
                  Dec(i);
          if i < 0 then
            i := Count - 1;
        end;
        #80: begin
          Inc(i);
          if i >= Count then
            i := 0;
        end;
      end;
    end;
  until ch = #13;
  Menu := i;
end;

procedure MENU1(x_,y_,x__,y__:integer;s:string;c:word);
begin
     SetColor(c);
     RecTangle(x_,y_,x__,y__);
     SetColor(White);
     OutTextXY(round(x_+(x__-x_-TextWidth(s))/2),round(y_+(y__-y_)/2),s);
end;

procedure _case_(var x_,y_,x__,y__:integer;var q:char;var r:integer);
var s:string;
begin
   case q of
         '1':begin
               {Menu1(x_,y_,x__,y__,s,white);}
               x_:=200;
               y_:=150;
               x__:=300;
               y__:=200;
               s:='R=15';
               Menu1(x_,y_,x__,y__,s,13);
               r:=15;
             end;
         '2':begin
              { Menu1(x_,y_,x__,y__,s,white); }
               x_:=350;
               y_:=150;
               x__:=450;
               y__:=200;
               s:='R=25';
               Menu1(x_,y_,x__,y__,s,13);
               r:=25;
             end;
         end;
end;




begin
Gd := Detect;
InitGraph (Gd, Gm, '');
If GraphResult <> grOk then halt(1);

repeat    settextStyle(4,0,6);
 Choise := Menu ('INFO'#13'Ypravlenie'#13'Moving Balls'#13'Exit');
 case Choise of
 0 : begin cleardevice;
           setcolor(7);
          settextstyle(4,0,3);

          settextjustify ( CenterText, CenterText);
          h := Textheight('A') + 10;
          outTextxY(getmaxx div 2, getmaxy div 4 - h, 'Kursovay rabota:');
          SetColor(13);
          outTextxY ( getmaxx div 2, getmaxy div 4 + h, '"M O V I N G   C I R C L E S"');
          SetColor (7);
          outtextxy( getmaxx div 2, getmaxy div 4  + 2*h, 'Podgotovila:');
          outtextxy ( getmaxx div 2, getmaxy div 4 + 3*h, 'Stydentka gr. ** - 11');
          outtextxy(getmaxx div 2, getmaxy div 4 + h*4, '******** Marina');
          outtextxy( getmaxx div 2, getmaxy div 4 + 6*h, 'Thanks for attention!');


      end;

 1:  begin   cleardevice;
          setcolor (7);
          settextstyle(4,0,3);
          h := textheight('A') + 10;
          setColor (13);
          outTextXY(getmaxx div 2, getmaxy div 4 + 6*h, 'Exit in main menu: Enter;' );
           outTextXY(getmaxx div 2, getmaxy div 4 + 7*h, 'Exit iz MOVING CIRCLES: Esc -> Enter;' );
          outTextxY(getmaxx div 2, getmaxy div 4 - h, 'Your moshete regylirovati skorosti shariv:');
          SetColor(7);
          outtextxy(getmaxx div 2 - 150, getmaxy div 4 + h, 'Pink Circle:');
          outTextXY(getmaxx div 2 - 150, getmaxy div 4 + 2*h, 'Yveli4enie skorosti : ->');
          outTextXY(getmaxx div 2 - 150, getmaxy div 4 + 3*h, 'Ymenshenie skorosti : <-');
          outtextxy(getmaxx div 2+ 170, getmaxy div 4 + h, 'White Circle:');
          outtextxy(getmaxx div 2+ 170, getmaxy div 4 + 2*h, 'Yveli4enie skorosti: +');
          outtextxy(getmaxx div 2+ 170, getmaxy div 4 + 3*h, 'Ymenshenie skorosti: -');


     end;
 2: begin cleardevice; randomize;
x1 := 50; y1 := 200; x_ := 170; y_ := 200;
x2 := 400; y2 := 300; x__ := 300; y__ := 250;
{r1 := 40; r2 := 40;}
SetTextStyle (4, 0, 3);
h := textheight('A') + 10;
settextjustify ( CenterText, CenterText);

Menu1(x_,y_,x__,y__,'R=15',13);
Menu1(x_+150,y_,x__+150,y__,'R=25',13);
outtextxY(x_-10, y_-20, '1:');
outtextxY(x_+140, y_-20, '2:');
OutTextXy (getmaxx div 2, getmaxy div 4 - h, 'Zadaite radiys nashatiem nyshogo 4isla:' );
{if KeyPressed then
             begin }

                q:=readkey;
               _case_(x_,y_,x__,y__, q, r);
               if  (q <> '1') and (q <>'2') then
                   begin
                        t := 5;
                        ClearDevice;
                        SeTTextStyle(4, 0, 6);
                        settextjustify ( CenterText, CenterText);
                        while (GetMaxY div 2 - t) > 0 do begin
                              for i := 0 to 15 do begin
                        SetColor (i mod 13);
                        OutTextXY (getMaxX div 2, getMaxY div 2 - t, 'ERROR!');
                        Delay (40000);
                        Cleardevice;
                        t := t + 5;
                        end;
                        end;
                        setColor(7);
                        OutTextXY (getMaxX div 2, getMaxY  div 2 + 30, 'Press any key for Exit!');
                        readkey; halt (1);

                   end;
{begin}cleardevice;
speed1 := 6; speed2 := 4;
angle1 := random(628)/100;    angle2 := random(628)/200;
bgC := 0;
Setcolor(0);
rectangle (1,1, getMaxX - 1, getMaxY - 1);
repeat
begin
 draw (x1, y1, r, 7);
 draw (x2, y2, r, 13 );
 delay(15100);
 escape (x1, y1, r, bgC);
 escape (x2, y2, r, bgC);
 move (x1, y1, angle1, speed1);
 move (x2, y2, angle2, speed2);
 border1 (x1, y1, r);
 border2 (x2, y2, r);
 balls_hit_2;
end;
if keypressed then begin
   c := readkey;
   if c = '+' then
      begin
           inc(speed1);
           if speed1 >= 60 then
              speed1 := 60;
      end;
   if c = '-' then
      begin
           dec(speed1);
           if speed1 <= 1 then
              speed1 := 1;
      end;
   if c = #77
    then
      begin
           inc(speed2);
           if speed2 >= 50 then
              speed2 := 50;
      end;
   if c = #75 then
      begin
           dec(speed2);
           if speed2 <= 5 then
              speed2 := 5;
      end;
   end;
until c = #27;
end;
{end;}

3 :  begin  clearDevice;
            SetTExtStyle(4, 0, 7);
            SetColor(13);
            while (GetMaxY div 2 - t) > 0 do begin
                              for i := 0 to 15 do begin
                        SetColor (i mod 13);
                        OutTextXY (getMaxX div 2, getMaxY div 2 - t, 'Bye, Bye!');
                        Delay (40000);
                        Cleardevice;
                        t := t + 5;
                        end;
                        end;
            readkey; halt (1);
     end;
end;
readkey;
until Choise = 3;
readkey;
closegraph;
end.