Что делают процедуры?

unit PaintForm;
 
interface
 
uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, ExtCtrls,
  Polyhedrons;
 
type
  TForm1 = class(TForm)
    Timer1: TTimer;
    procedure Timer1Timer(Sender: TObject);
    procedure FormCreate(Sender: TObject);
    procedure FormPaint(Sender: TObject);
  private
    Cube: Polyhedron;
  public
    { Public declarations }
  end;
 
var
  Form1: TForm1;
 
implementation
 
{$R *.dfm}
 
const Len = 200;
      startX = 200;
      startY = 100;
 
procedure TForm1.Timer1Timer(Sender: TObject);
var DateTime : TDateTime;
begin
  cube.rotate(0.01);
  refresh;
end;
 
procedure TForm1.FormCreate(Sender: TObject);
var
n,i,a,b:integer;
x,y,z:real;
begin
  cube := Polyhedron.create;
  reset(input,'input.txt');
  read(n);
  for i := 1 to n do
    begin
    read(x,y,z);
    cube.addPoint(x*Len,y*Len,z*Len);
    end;
  read(n);
  for i := 1 to n do
    begin
    read(a,b);
    cube.addEdge(a,b);
    end;
  system.close(input);
  cube.shift(-Len/2,-Len/2,0);
end;
 
procedure TForm1.FormPaint(Sender: TObject);
var i: integer;
xa, ya, xb, yb: real;
a, b:point;
begin
 
  with cube do
    for i := 0 to length(edges)-1 do
      begin
      a := points[edges[i].a];
      b := points[edges[i].b];
      xa := a.x + a.y * 0.5 + startX;
      xb := b.x + b.y * 0.5 + startX;
      ya := a.z + a.y * 0.5 + startY;
      yb := b.z + b.y * 0.5 + startY;
 
      canvas.MoveTo(round(xa),round(ya));
      canvas.LineTo(round(xb),round(yb));
 
      end;
end;
 
end.