unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, ExtCtrls, Math, ComCtrls;

type
  TForm1 = class(TForm)
    GroupBox1: TGroupBox;
    GroupBox2: TGroupBox;
    PaintBox1: TPaintBox;
    EditL: TEdit;
    EditH: TEdit;
    EditNum: TEdit;
    EditRad: TEdit;
    Label1: TLabel;
    Label2: TLabel;
    Label3: TLabel;
    Label4: TLabel;
    UpDownNum: TUpDown;
    ButtonGo: TButton;
    ButtonStop: TButton;
    ButtonColor: TButton;
    ButtonFon: TButton;
    ColorDialog1: TColorDialog;
    Timer1: TTimer;
    procedure FormCreate(Sender: TObject);
    procedure ButtonFonClick(Sender: TObject);
    procedure ButtonColorClick(Sender: TObject);
    procedure ButtonGoClick(Sender: TObject);
    procedure Timer1Timer(Sender: TObject);
    procedure ButtonStopClick(Sender: TObject);
    procedure UpDownNumClick(Sender: TObject; Button: TUDBtnType);
    procedure EditNumKeyPress(Sender: TObject; var Key: Char);
    procedure ButtonGoKeyPress(Sender: TObject; var Key: Char);
    procedure GroupBox1Click(Sender: TObject);
  private
    { Private declarations }
    procedure Painting;
  public
    { Public declarations }
  end;

type
TMolekula = class
 Fx, Fy, FVx, FVy, FR : Integer;
public
 constructor Create(x, y, Vx, Vy : integer);
 procedure Wall(i : integer; width, height : integer);
 procedure Strike(i : integer);
end;

type
TMolekulaList = Class(TList)
public
 procedure Add(Mol : TMolekula);
 procedure Clear;
 procedure Delete(n : integer);
end;

const MaxSpeed=10;

var
  Form1: TForm1;
  Molcolor: TColor;
  FonColor: TColor;
  Mollist: TMolekulaList;
  pbWidth, pbHeight: integer;
  Rad: integer;

implementation

{$R *.dfm}

Constructor TMolekula.Create(x, y, Vx, Vy : integer);
begin
 Fx := x;
 Fy := y;
 FVx := Vx;
 FVy := Vy;
 FR := Rad;
end;

function CreateMol: TMolekula;
var x, y, vx, vy : integer;
begin
x := RandomRange(Rad, pbWidth - Rad);
y := RandomRange(Rad, pbHeight - Rad);
Vx:= RandomRange(1, MaxSpeed);
Vy:= RandomRange(1, MaxSpeed);
if RandomRange(1, 100) > 50 then Vx := -Vx;
if RandomRange(1, 100) > 50 then Vy := -Vy;
Result := TMolekula.Create(x, y, Vx, Vy);
end;

Function DistanceBetween(Mol1, Mol2 : TMolekula) : real;
begin
 Result:= sqrt(sqr(Mol1.Fx - Mol2.Fx) + sqr(Mol1.Fy - Mol2.Fy));
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
 MolColor := clBlack;
 FonColor := clSilver;
 MolList := TMolekulaList.Create;
 Randomize;
end;

procedure TForm1.GroupBox1Click(Sender: TObject);
begin

end;

procedure TForm1.ButtonFonClick(Sender: TObject);
begin
if ColorDialog1.Execute then
 FonColor := ColorDialog1.Color;
end;

procedure TForm1.ButtonColorClick(Sender: TObject);
begin
if ColorDialog1.Execute then
 MolColor := ColorDialog1.Color;
end;

procedure TForm1.ButtonGoClick(Sender: TObject);
var i, n : integer;
 Mol : TMolekula;
begin
 PaintBox1.Width := pbWidth;
 PaintBox1.Height := pbHeight;
 pbWidth := StrToInt(editL.Text);
 pbHeight:= StrToInt(editH.Text);
 n := strToInt(editNum.Text);
 Rad := strToInt(editRad.Text);

 if (Rad=0) or (n=0) then
 begin
   ShowMessage ('Количество молекул и/или радиус молекул не могут быть равны 0');
   exit;
 end;

if (pbWidth*pbHeight)<Trunc (n*pi*Rad*Rad) then
begin
  ShowMessage ('Сосуд маленький для таких молекул');
  exit;
end;

 MolList.Clear;

   MolList.Clear;
 for i := 1 to n do
 begin
 Mol := CreateMol;
 MolList.Add(Mol);
 end;
 timer1.Enabled:=true;
 ButtonStop.Caption:= 'Стоп';
end;

procedure TForm1.ButtonGoKeyPress(Sender: TObject; var Key: Char);
begin
if key =#13 then ButtonGo.Click;
end;

procedure TForm1.Timer1Timer(Sender: TObject);
var x, y : integer;
 i : integer;
 Mol : TMolekula;
begin
 for i:=0 To MolList.Count-1 do
 begin
 Mol := TMolekula(MolList.Items[i]);
 Mol.Fx := Mol.Fx + Mol.FVx;
 Mol.Fy := Mol.Fy + Mol.FVy;
 Mol.Wall(i, pbwidth, pbheight);
 Mol.Strike(i);
 Painting;
 end;
end;

procedure TForm1.ButtonStopClick(Sender: TObject);
begin
Timer1.Enabled:= not Timer1.Enabled;
if Timer1.Enabled then
 ButtonStop.Caption:= 'Стоп'
else
 ButtonStop.Caption:= 'Продолжить'
end;

procedure TForm1.EditNumKeyPress(Sender: TObject; var Key: Char);
begin
if key =#13 then
begin
ButtonGo.Click;
end;
end;
procedure TForm1.UpDownNumClick(Sender: TObject; Button: TUDBtnType);
var Mol: TMolekula;
begin
if ButtonStop.Caption = 'Стоп' then
 if Button = btNext then
 begin
 Mol := CreateMol;
 MolList.Add(Mol);
 end
 else
 if MolList.Count > 1 then
 MolList.Delete(0);
end;

procedure TMolekula.Wall(i:integer; width, height:integer);
var
Mol : TMolekula;
begin
 Mol := TMolekula(MolList.Items[i]);
 if Mol.Fx + Rad >= width then
 begin
 Mol.FVx := -Mol.FVx;
 Mol.Fx := width - Rad;
 end
 else
 if Mol.Fy + Rad >= height then
 begin
 Mol.FVy := -Mol.FVy;
 Mol.Fy := height - Rad;
 end
 else
 if Rad >= width then
 begin
 Mol.FVx := -Mol.FVx;
 Mol.Fx := width;
 end
 else
 if Rad >= height then
 begin
 Mol.FVy := -Mol.FVy;
 Mol.Fy := height;
 end;
 if Mol.Fx - Rad <= 0 then
 begin
 Mol.FVx := -Mol.FVx;
 Mol.Fx := Rad;
 end
 else
 if Mol.Fy - Rad <= 0 then
 begin
 Mol.FVy := -Mol.FVy;
 Mol.Fy := Rad;
 end;
end;
procedure TMolekula.Strike(i : integer);
var j : byte;
 Mol1, Mol2 : TMolekula;
 temp : integer;
begin
 Mol1:=TMolekula(MolList.Items[i]);
 for j := 0 to MolList.Count - 1 do
 begin
 if j <> i then
  begin
  Mol2 := TMolekula(MolList.Items[j]);
  if DistanceBetween(Mol1, Mol2) <= 2 * Rad then
    begin
    temp := Mol1.FVx;
    Mol1.FVx := Mol2.FVx;
    Mol2.FVx := temp;
    temp := Mol1.FVy;
    Mol1.FVy := Mol2.FVy;
    Mol2.FVy := temp;
    break;
    end;
  end;
 end;
end;

procedure TMolekulaList.Add(Mol: TMolekula);
begin
 inherited Add(Mol);
end;

procedure TMolekulaList.Clear;
var i: integer;
begin
 for i := 0 to Count - 1 do TMolekula(Items[i]).Free;
 Inherited Clear;
end;

procedure TMolekulaList.Delete(n: integer);
begin
 if (n >=0) and (n <= Count - 1) then
 begin
 TMolekula(Items[n]).Free;
 Inherited Delete(n);
 end;
end;

procedure TForm1.Painting;
var
 i : Integer;
 Mol : TMolekula;
begin
 paintBox1.Canvas.Brush.Color := FonColor;
 PaintBox1.Canvas.Rectangle(0, 0, pbWidth, pbHeight);
 PaintBox1.Canvas.Brush.Color := MolColor;
 for i := 0 to MolList.Count - 1 do
 begin
 Mol := TMolekula(MolList.Items[i]);
 PaintBox1.Canvas.Ellipse(Mol.Fx - Rad, Mol.Fy - Rad,
 Mol.Fx + Rad, Mol.Fy + Rad);
 end;
end;

end.