unit Unit9;
{
  This software has been designed and is CopyLefted
  by Han de Bruijn:
                          (===)
                         @-O^O-@
                          #/_\#
                           ###
}
interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, ExtCtrls, Grafisch;

type
  TForm1 = class(TForm)
    Image1: TImage;
    procedure Scheppen(Sender: TObject);
    procedure Toetsdruk(Sender: TObject; var Key: Char);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

var
  keer : integer;

var
  x,y,D : array[1..4] of double;

procedure Tekst(nr : integer);
{
  Display Enumerations
}
var
  Ox,Oy : integer;
begin
  with Form1.Image1.Canvas do
  begin
    Ox := PenPos.x; Oy := PenPos.y;
    TextOut(Ox,Oy,IntToStr(nr));
    MoveTo(Ox,Oy);
  end;
end;

procedure Parabool;
{
  Draw Parabola
}
var
  Ad,Bd,Cd : double;
  Ax,Bx,Cx,Dx : double;
  Ay,By,Cy,Dy : double;
  a_x,a_y,v_x,v_y,s_x,s_y : double;
  p,q,t : double;
  k : integer;
begin
  Ax := (+x[1]+x[2]+x[3]+x[4])/4;
  Bx := (-x[1]+x[2]-x[3]+x[4])/2;
  Cx := (-x[1]-x[2]+x[3]+x[4])/2;
  Dx := (+x[1]-x[2]-x[3]+x[4]);
  Ay := (+y[1]+y[2]+y[3]+y[4])/4;
  By := (-y[1]+y[2]-y[3]+y[4])/2;
  Cy := (-y[1]-y[2]+y[3]+y[4])/2;
  Dy := (+y[1]-y[2]-y[3]+y[4]);
  Ad := (+D[1]+D[2]+D[3]+D[4])/4;
  Bd := (-D[1]+D[2]-D[3]+D[4])/2;
  Cd := (-D[1]-D[2]+D[3]+D[4])/2;
  a_x := -Dx*Bd;
  a_y := -Dy*Bd;
  v_x := Cd*Bx-Cx*Bd-Dx*Ad;
  v_y := Cd*By-Cy*Bd-Dy*Ad;
  s_x := Cd*Ax-Cx*Ad;
  s_y := Cd*Ay-Cy*Ad;
  Form1.Image1.Canvas.Pen.Width := 4;
  Form1.Image1.Canvas.Pen.Color := clBlue;
  t := -1/2;
  p := (a_x*sqr(t)+v_x*t+s_x)/Cd;
  q := (a_y*sqr(t)+v_y*t+s_y)/Cd;
  Form1.Image1.Canvas.MoveTo(x2i(p),y2j(q));
  for k := 1 to Wijd do
  begin
    t := k/Wijd-1/2;
    p := (a_x*sqr(t)+v_x*t+s_x)/Cd;
    q := (a_y*sqr(t)+v_y*t+s_y)/Cd;
    Form1.Image1.Canvas.LineTo(x2i(p),y2j(q));
  end;
end;

procedure Tekenen;
const
  eps : double = 0.02;
var
  xi,eta,p,q : double;
  k,i,j,m,n : integer;
  nr : string[2];
begin
  for k := 1 to 4 do
  begin
    x[k] := Random-1/2; y[k] := Random-1/2;
  end;
  D[1] := (x[2]-x[1])*(y[3]-y[1])-(x[3]-x[1])*(y[2]-y[1]);
  D[2] := (x[2]-x[1])*(y[4]-y[2])-(x[4]-x[2])*(y[2]-y[1]);
  D[3] := (x[4]-x[3])*(y[3]-y[1])-(x[3]-x[1])*(y[4]-y[3]);
  D[4] := (x[4]-x[3])*(y[4]-y[2])-(x[4]-x[2])*(y[4]-y[3]);
  for j := 0 to Hoog do
  begin
    eta := j/Hoog-1/2;
    eta := 5*eta; { enlarged }
    for i := 0 to Wijd do
    begin
      xi := i/Wijd-1/2;
      xi := 5*xi; { enlarged }
      p := (1/2-xi)*(1/2-eta)*x[1]
         + (1/2+xi)*(1/2-eta)*x[2]
         + (1/2-xi)*(1/2+eta)*x[3]
         + (1/2+xi)*(1/2+eta)*x[4];
      q := (1/2-xi)*(1/2-eta)*y[1]
         + (1/2+xi)*(1/2-eta)*y[2]
         + (1/2-xi)*(1/2+eta)*y[3]
         + (1/2+xi)*(1/2+eta)*y[4];
      m := x2i(p); n := y2j(q);
      Form1.Image1.Canvas.Pixels[m,n] := clGray;
    end;
  end;
  Form1.Image1.Canvas.Pen.Width := 2;
  Form1.Image1.Canvas.Pen.Color := clBlack;
  Form1.Image1.Canvas.Moveto(x2i(x[1]),y2j(y[1])); Tekst(1);
  Form1.Image1.Canvas.Lineto(x2i(x[2]),y2j(y[2])); Tekst(2);
  Form1.Image1.Canvas.Lineto(x2i(x[4]),y2j(y[4])); Tekst(4);
  Form1.Image1.Canvas.Lineto(x2i(x[3]),y2j(y[3])); Tekst(3);
  Form1.Image1.Canvas.Lineto(x2i(x[1]),y2j(y[1]));
  Parabool;
  nr[1] := char((keer div 10)+byte('0'));
  nr[2] := char((keer mod 10)+byte('0'));
  Form1.Image1.Picture.SaveToFile('film\9P'+nr+'.bmp');
end;

procedure TForm1.Scheppen(Sender: TObject);
begin
  TV(Form1.Image1);
  ClearDevice;
  xmin := -0.6; xmax := +0.6;
  ymin := -0.6; ymax := +0.6;
  Form1.Image1.Canvas.Font.Size := 15;
  keer := 0;
  Tekenen;
end;

procedure TForm1.Toetsdruk(Sender: TObject; var Key: Char);
begin
  ClearDevice;
  keer := keer + 1;
  Tekenen;
end;

end.