EXEMPLE D'APPLICATION DE TEXTURE AVEC OPENGL

unit Unit1;

interface

uses
  {*** Implementation d'OPENGL 1.2 ***}
  OpenGL12,
  Windows, Forms, Classes, ExtCtrls, Messages,Controls,sysutils,
  StdCtrls,Graphics,Dialogs;

type
  TMainForm = class(TForm)
    procedure FormCreate(Sender: TObject);
    procedure FormDestroy(Sender: TObject);
    procedure FormPaint(Sender: TObject);
    procedure FormKeyPress(Sender: TObject; var Key: Char);
    procedure FormResize(Sender: TObject);
    procedure FormMouseDown(Sender: TObject; Button: TMouseButton ; Shift: TShiftState ; X, Y: Integer);
    procedure FormMouseUp(Sender: TObject; Button: TMouseButton;
      Shift: TShiftState; X, Y: Integer);
    procedure FormMouseMove(Sender: TObject; Shift: TShiftState; X,
      Y: Integer);
    procedure FormShow(Sender: TObject);
  private
    RC      : HGLRC;
    Souris  : Boolean;
    rx,ry   : integer;
    dx,dy   : integer;
    Texture : TGLuint;

    procedure WMEraseBkgnd(var Message: TWMEraseBkgnd); message WM_ERASEBKGND;
  end;

var
  MainForm: TMainForm;
  {*** On déclare une texture comme un tableau à 2 dimensions
       de la taille de la texture à charger. Attention, pour éviter des
       lignes noires trés disgracieuses entre les raccords de textures, je
       commence mon tableau à 1 ***}
  Tex     : Array[1..256,1..256]of TGluInt;

implementation

{$R *.DFM}

{*** Chargement de la texture : comme je suis fénéant, je profite de l'objet
     "TPicture" offert par Delphi ***}
Function ChargerTexture(Fichier : String) : Boolean;
Var
   M : Integer;
   N : Integer;
   Img : TPicture;
Begin
     Result := False;
     If FileExists(Fichier) Then Begin
          Img := Tpicture.Create;
          Img.LoadFromFile(Fichier);
          For N := 1 To 256 Do
              For M := 1 To 256 Do
                  Tex[N,M] := Img.Bitmap.Canvas.Pixels[M,N];
          Result := True;
     End;
End;

{*** Création d'un rendering context au démarrage de l'appli ***}
procedure TMainForm.FormCreate(Sender: TObject);
Var
     Machin : Hpalette;
begin

  RC:=CreateRenderingContext(Canvas.Handle,[opDoubleBuffered],32,0,0,0,0,Machin);
  Souris := False;
end;

{*** Suppression du rendering context à la fermeture de l'appli ***}
procedure TMainForm.FormDestroy(Sender: TObject);
begin
  DestroyRenderingContext(RC);
end;

{*** Procedure principale : dessiner l'objet dans le rendering context ***}
procedure TMainForm.FormPaint(Sender: TObject);
begin
  ActivateRenderingContext(Canvas.Handle,RC);
  {*** Options OpenGL ***}
  glClear(GL_COLOR_BUFFER_BIT or GL_DEPTH_BUFFER_BIT);
  glMatrixMode(GL_MODELVIEW);
  glLoadIdentity;
  {*** Placer le point de vue ***}
  gluLookAt(0,0,7,0,0,-10,0,1,0);

  {*** Appliquer la rotation ***}
  glRotatef(ry,1,0,0);
  glRotatef(-rx,0,1,0);
  {*** Activer la gestion des textures ***}
  glEnable(GL_TEXTURE_2D);
  glEnable(GL_DEPTH_TEST);
  glTexEnvf(GL_TEXTURE_ENV,GL_TEXTURE_ENV_MODE,GL_REPLACE);

  glColorMaterial(GL_FRONT_AND_BACK,GL_SPECULAR);
  {*** Dessiner un bô cube et appliquer la texture ***}
  glBegin(GL_QUADS);

		glTexCoord2i(0,0);glVertex3i(-1,-1,-1);
		glTexCoord2i(1,0);glVertex3i(+1,-1,-1);
		glTexCoord2i(1,1);glVertex3i(+1,+1,-1);
		glTexCoord2i(0,1);glVertex3i(-1,+1,-1);

		glTexCoord2i(0,0);glVertex3i(-1,-1,+1);
		glTexCoord2i(1,0);glVertex3i(+1,-1,+1);
		glTexCoord2i(1,1);glVertex3i(+1,+1,+1);
		glTexCoord2i(0,1);glVertex3i(-1,+1,+1);

		glTexCoord2i(0,0);glVertex3i(+1,-1,-1);
		glTexCoord2i(1,0);glVertex3i(+1,-1,+1);
		glTexCoord2i(1,1);glVertex3i(+1,+1,+1);
		glTexCoord2i(0,1);glVertex3i(+1,+1,-1);

		glTexCoord2i(0,0);glVertex3i(-1,-1,-1);
		glTexCoord2i(1,0);glVertex3i(-1,-1,+1);
		glTexCoord2i(1,1);glVertex3i(-1,+1,+1);
		glTexCoord2i(0,1);glVertex3i(-1,+1,-1);

		glTexCoord2i(0,0);glVertex3i(-1,+1,-1);
		glTexCoord2i(1,0);glVertex3i(+1,+1,-1);
		glTexCoord2i(1,1);glVertex3i(+1,+1,+1);
		glTexCoord2i(0,1);glVertex3i(-1,+1,+1);

		glTexCoord2i(0,0);glVertex3i(-1,-1,+1);
		glTexCoord2i(1,0);glVertex3i(+1,-1,+1);
		glTexCoord2i(1,1);glVertex3i(+1,-1,-1);
		glTexCoord2i(0,1);glVertex3i(-1,-1,-1);
  glEnd();
  glDisable(GL_TEXTURE_2D);
  {*** Inverser les buffers ***}
  SwapBuffers(Canvas.Handle);
  DeactivateRenderingContext;
end;

procedure TMainForm.FormKeyPress(Sender: TObject; var Key: Char);
begin
  if Key = #27 then Application.Terminate;
end;

{*** Initialisation à chaque redimmensionnement de la fenêtre ***}
procedure TMainForm.FormResize(Sender: TObject);
Var 
  Ch : String;
begin
  Ch := ExtractFilePath(Application.Exename);
  If Ch[Length(Ch)] <> '\' Then Ch := Ch + '\';

  If not ChargerTexture(Ch + 'Texture.Bmp') then ShowMessage('Impossible de charger la texture');
  wglMakeCurrent(Canvas.handle,RC);
  glViewport(0,0,Width,Height);
  glMatrixMode(GL_PROJECTION);
  glLoadIdentity;
  gluPerspective(35,Width/Height,1,100);
  {*** Options pour la gestion des textures ***}
  glPixelStorei(GL_UNPACK_ALIGNMENT,1);
  glGenTextures(1, @Texture);
  glBindTexture(GL_TEXTURE_2D, Texture);
  glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR);
  glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR);
  glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_WRAP_S,GL_REPEAT);
  glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_WRAP_T,GL_REPEAT);
  {*** Chargement de la texture ***}
  glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 256 ,256 , 0, GL_RGBA,GL_UNSIGNED_BYTE,@Tex);
  wglMakeCurrent(0,0);
  Refresh;
end;

{*** Eviter le clignotement du fond de la feuille entre les swapbuffers ***}
procedure TMainForm.WMEraseBkgnd(var Message: TWMEraseBkgnd);
begin
  Message.Result:=1;
end;

{*** Routine faite avec les pieds pour faire pivoter le cube ***}
procedure TMainForm.FormMouseDown(Sender: TObject; Button: TMouseButton;
  Shift: TShiftState; X, Y: Integer);
begin
Souris := TRue;
end;
procedure TMainForm.FormMouseUp(Sender: TObject; Button: TMouseButton;
  Shift: TShiftState; X, Y: Integer);
begin
Souris := False;
end;

procedure TMainForm.FormMouseMove(Sender: TObject; Shift: TShiftState; X,
  Y: Integer);
begin
  If Souris then begin
  ry := y-dy;
  rx := dx-x;
  Repaint;
  end
  else begin
       dx := x ;
       dy := y ;
  end;
  Caption := '( X : '+inttostr(x)+' - Y : '+inttostr(y)+' )';
end;

{*** Forcer l'initialisation d'OpenGL à l'affichage de la feuille ***}
procedure TMainForm.FormShow(Sender: TObject);
begin
     MainForm.FormResize(Nil);
end;

{*** Tiens ? a pu ! ***}
end.