CODEWITHSUNDEEP
delphiopenglrotationlighting
proggamer12
proggamer12

Reputation: 302

delphi and opengl: light is rotating with the cube

Question was wrote by translator, so I don't know is it orthographically right. I started learning Opengl and came to the following problem: when I rotate the cube, the light is also rotated. I tried to change coordinates of light in every frame, but it did not help. Tell me: what went wrong. If not trouble, it was possible, would result in a revised version.

Code:

unit MainUnit;

interface

uses
  Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes,     Vcl.Graphics,
  Vcl.Controls, Vcl.Forms, Vcl.Dialogs,dglOpenGL,dglut;

type
  TFMainForm = class(TForm)
    procedure FormCreate(Sender: TObject);
    procedure FormResize(Sender: TObject);
    procedure FormDestroy(Sender: TObject);
    procedure FormKeyPress(Sender: TObject; var Key: Char);
  private

  procedure SetupGL;
  procedure uzglLightEnable;
  procedure IdleHandler(Sender : TObject; var Done : Boolean);

  public

  procedure Render;

  end;

var
  FMainForm: TFMainForm;
  dc:hdc;
  hrc:hglrc;
  XRot,YRot,ZRot:Single;

  LightPos:TGLArrayf4;
  BlueArray:TGLArrayf4;
  GreenArray:TGLArrayf4;
  myTex: glUint;

  FrontNormal: TGLvectorf3=(0,0,1);
  BackNormal: TGLvectorf3 =(0,0,-1);
  LeftNormal: TGLvectorf3 =(-1,0,0);
  RightNormal: TGLvectorf3=(1,0,0);
  UpNormal: TGLvectorf3   =(0,1,0);
  DownNormal: TGLvectorf3 =(0,-1,0);

  FrontDownLeft :TGLvectorf3 = (-1,-1,-1);
  FrontDownRight:TGLvectorf3 = (1,-1,-1);
  FrontUpLeft   :TGLvectorf3 = (-1,1,-1);
  FrontUpRight  :TGLvectorf3 = (1,1,-1);

  BackDownLeft :TGLvectorf3 = (-1,-1,1);
  BackDownRight:TGLvectorf3 = (1,-1,1);
  BackUpLeft   :TGLvectorf3 = (-1,1,1);
  BackUpRight  :TGLvectorf3 = (1,1,1);


const
  NearClipping = 0.1;
  FarClipping  = 200;

  procedure uzglTriangle(x1,y1,z1,x2,y2,z2,x3,y3,z3:single);

  procedure uzglCube;

    implementation

    {$R *.dfm}



    procedure uzglTriangle(x1,y1,z1,x2,y2,z2,x3,y3,z3:single);
    begin
    glBegin(GL_TRIANGLES);
    glColor3f(0.3,0,0);glVertex3f(x1,y1,z1);
    glColor3f(0.25,1,0);glVertex3f(x2,y2,z2);
    glColor3f(0.7,0,1);glVertex3f(x3,y3,z3);
    glEnd;

    end;

    procedure uzglCube;
    begin
glBegin(GL_QUADS);
// Beginning of front
glNormal3fv(@FrontNormal);
glVertex3fv(@FrontDownLeft);
glVertex3fv(@FrontDownRight);
glVertex3fv(@FrontUpRight);
glVertex3fv(@FrontUpLeft);
// End of front
glEnd;


glBegin(GL_QUADS);
// Beginning of left
glNormal3fv(@LeftNormal);
glVertex3fv(@FrontDownLeft);
glVertex3fv(@FrontUpLeft);
glVertex3fv(@BackUpLeft);
glVertex3fv(@BackDownLeft);
// End of left
glEnd;

glBegin(GL_QUADS);
  // Beginning of right
  glNormal3fv(@RightNormal);
  glVertex3fv(@FrontDownRight);
  glVertex3fv(@FrontUpRight);
  glVertex3fv(@BackUpRight);
  glVertex3fv(@BackDownRight);
  // End of right
glEnd;

glBegin(GL_QUADS);
// Beginning of up
glNormal3fv(@UpNormal);
glVertex3fv(@FrontUpRight);
glVertex3fv(@FrontUpLeft);
glVertex3fv(@BackUpLeft);
glVertex3fv(@BackUpRight);
// End of up
glEnd;

glBegin(GL_QUADS);
// Beginning of down
glNormal3fv(@DownNormal);
glVertex3fv(@FrontDownRight);
glVertex3fv(@FrontDownLeft);
glVertex3fv(@BackDownLeft);
glVertex3fv(@BackDownRight);
// End of down
glEnd;

glBegin(GL_QUADS);
// Beginning of back
glNormal3fv(@BackNormal);
glVertex3fv(@BackDownLeft);
glVertex3fv(@BackDownRight);
glVertex3fv(@BackUpRight);
glVertex3fv(@BackUpLeft);
// End of back
glEnd;



end;
  procedure TFMainForm.SetupGL;
  begin
  glClearColor(0.3,0.4,0.7,0.0);
  glEnable(GL_DEPTH_TEST);
  glEnable(GL_SMOOTH);
  glDepthFunc(GL_LEQUAL);
  glEnable(GL_TEXTURE_2D);
  uzglLightEnable;
  LightPos[0]:=0;
  LightPos[1]:=0;
  LightPos[2]:=1;
  LightPos[3]:=1;

  end;

procedure TFMainForm.uzglLightEnable;

begin
glEnable(GL_LIGHTING);
glEnable(GL_LIGHT0);
glEnable(GL_COLOR_MATERIAL);
end;

procedure TFMainForm.Render;
var i:integer;
begin
  glClear(GL_COLOR_BUFFER_BIT or GL_DEPTH_BUFFER_BIT);
  glMatrixMode(GL_PROJECTION);
  glLoadIdentity;
  gluPerspective(45.0,ClientWidth/ClientHeight,NearClipping,FarClipping);
  glTranslatef(0,0,-5);

  glPushMatrix;
  glRotatef(XRot,1,0,0);
  uzglCube;
  glPopMatrix;

  glLightfv(GL_LIGHT0, GL_POSITION,@LightPos);

  SwapBuffers(dc);

  XRot:=XRot+1;

end;

procedure TFMainForm.IdleHandler(Sender : TObject; var Done : Boolean);
begin
Render;
Sleep(25);

Done:=false;
end;

procedure TFMainForm.FormCreate(Sender: TObject);
begin
dc:=GetDC(Handle);

if not InitOpenGL then
                  begin
                  ShowMessage('Печалька... Инициализация провалилась');
                  Application.Terminate;
                  end;
hrc:=CreateRenderingContext       (dc,
                                   [opDoubleBuffered],
                                   32,
                                   24,
                                   8,
                                   0,
                                   0,
                                   0);

ActivateRenderingContext(dc,hrc);
SetupGL;
Application.OnIdle:=IdleHandler;

FMainForm.OnResize(self);
end;



procedure TFMainForm.FormResize(Sender: TObject);
var tmpBool:boolean;
begin
glViewport(0,0,ClientWidth,ClientHeight);
glMatrixMode(GL_PROJECTION);
glLoadIdentity;
gluPerspective(45.0,ClientWidth/ClientHeight,NearClipping,FarClipping);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity;

idleHandler(Sender, tmpBool);
end;


procedure TFMainForm.FormDestroy(Sender: TObject);
begin
DeactivateRenderingContext;
DestroyRenderingContext(hrc);
ReleaseDC(Handle,dc);
end;


procedure TFMainForm.FormKeyPress(Sender: TObject; var Key: Char);
begin

case key of
'q':LightPos[0]:=LightPos[0]+0.1;
'a':LightPos[0]:=LightPos[0]-0.1;
'w':LightPos[1]:=LightPos[1]+0.1;
's':LightPos[1]:=LightPos[1]-0.1;
'e':LightPos[2]:=LightPos[2]+0.1;
'd':LightPos[2]:=LightPos[2]-0.1;
end;
end;

end.

dglOpenGL: http://wiki.delphigl.com/index.php/dglOpenGL.pas/en

Upvotes: 0

Views: 1093

Answers (1)

Greeny
Greeny

Reputation: 124

i can spot a couple of things awry.

Firstly: your Normals are inconsistent. Change to

FrontNormal: TGLvectorf3=(0,0,1);
BackNormal: TGLvectorf3 =(0,0,-1);
LeftNormal: TGLvectorf3 =(1,0,0);
RightNormal: TGLvectorf3=(-1,0,0);
UpNormal: TGLvectorf3   =(0,-1,0);
DownNormal: TGLvectorf3 =(0,1,0);

Secondly: You are transforming your cube in the GL_PROJECTION matrix. The GL_PROJECTION matrix should only contain stuff neccessary to set up the projection.

Your cube & lights should be transformed by the GL_MODELVIEW matrix.

Your Projection only changes when the window size changes so, it can go in the FormResize event.

procedure TForm2.FormResize(Sender: TObject);
  var tmpBool:boolean;
begin
  glViewport(0,0,ClientWidth,ClientHeight);
  glMatrixMode(GL_PROJECTION);
  glLoadIdentity;
  gluPerspective(45.0,ClientWidth/ClientHeight,NearClipping,FarClipping);
  idleHandler(Sender, tmpBool);
end;

The GL_MODELVIEW matrix can be set up in the SetupGL proc. Notice the gluLookAt() command which sets up the view looking from (-2,3,-3) to (0,0,0). Set gluLookAt(0, 3, -3, 0,0,0, 0,1,0); to have a 'head on' view.

procedure TForm2.SetupGL;
begin
  glClearColor(0.3,0.4,0.7,0.0);
  glEnable(GL_DEPTH_TEST);
  glEnable(GL_SMOOTH);
  glDepthFunc(GL_LEQUAL);
  glEnable(GL_TEXTURE_2D);

  glMatrixMode(GL_MODELVIEW);
  glLoadIdentity;
  gluLookAt(-2, 3, -3, 0,0,0, 0,1,0);
  uzglLightEnable;
  LightPos[0]:=0;
  LightPos[1]:=0;
  LightPos[2]:=1;
  LightPos[3]:=1;
end;

The Render Proc becomes.

procedure TForm2.Render;
var i:integer;
begin
  glClear(GL_COLOR_BUFFER_BIT or GL_DEPTH_BUFFER_BIT);

  glMatrixMode(GL_MODELVIEW);
  glPushMatrix;
  glRotatef(XRot,1,0,0);
  uzglCube;

  if FTransformLights then
  begin
    glLightfv(GL_LIGHT0, GL_POSITION,@LightPos);
    glPopMatrix;
  end
  else
  begin
    glPopMatrix;
    glLightfv(GL_LIGHT0, GL_POSITION,@LightPos);
  end;

  SwapBuffers(dc);

  XRot:=XRot+1;
end;

Note: I have added a private form variable FTransformLights, which if true rotates the light with the cube, otherwise the lights do not rotate as they are transformed after the GL_MODELVIEW matrix is 'popped' back to it's original state (the identity).

I have added the 'x' key to toggle whether the light rotates or not. Here is the full modified listing. Hope that sorts it.

unit MainUnit;

interface

uses
  Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes,     Vcl.Graphics,
  Vcl.Controls, Vcl.Forms, Vcl.Dialogs,dglOpenGL;

type
  TFMainForm = class(TForm)
    procedure FormCreate(Sender: TObject);
    procedure FormResize(Sender: TObject);
    procedure FormDestroy(Sender: TObject);
    procedure FormKeyPress(Sender: TObject; var Key: Char);
  private
    FTransformLights:Boolean;
    procedure SetupGL;
    procedure uzglLightEnable;
    procedure IdleHandler(Sender : TObject; var Done : Boolean);
  public
    procedure Render;
  end;

var
  FMainForm: TFMainForm;
  dc:hdc;
  hrc:hglrc;
  XRot,YRot,ZRot:Single;

  LightPos:TGLArrayf4;
  BlueArray:TGLArrayf4;
  GreenArray:TGLArrayf4;
  myTex: glUint;

  FrontNormal: TGLvectorf3=(0,0,1);
  BackNormal: TGLvectorf3 =(0,0,-1);
  LeftNormal: TGLvectorf3 =(1,0,0);
  RightNormal: TGLvectorf3=(-1,0,0);
  UpNormal: TGLvectorf3   =(0,-1,0);
  DownNormal: TGLvectorf3 =(0,1,0);

  FrontDownLeft :TGLvectorf3 = (-1,-1,-1);
  FrontDownRight:TGLvectorf3 = (1,-1,-1);
  FrontUpLeft   :TGLvectorf3 = (-1,1,-1);
  FrontUpRight  :TGLvectorf3 = (1,1,-1);

  BackDownLeft :TGLvectorf3 = (-1,-1,1);
  BackDownRight:TGLvectorf3 = (1,-1,1);
  BackUpLeft   :TGLvectorf3 = (-1,1,1);
  BackUpRight  :TGLvectorf3 = (1,1,1);


const
  NearClipping = 0.1;
  FarClipping  = 200;

  procedure uzglTriangle(x1,y1,z1,x2,y2,z2,x3,y3,z3:single);
  procedure uzglCube;

implementation

{$R *.dfm}



  procedure uzglTriangle(x1,y1,z1,x2,y2,z2,x3,y3,z3:single);
  begin
    glBegin(GL_TRIANGLES);
    glColor3f(0.3,0,0);glVertex3f(x1,y1,z1);
    glColor3f(0.25,1,0);glVertex3f(x2,y2,z2);
    glColor3f(0.7,0,1);glVertex3f(x3,y3,z3);
    glEnd;

  end;

  procedure uzglCube;
  begin
    glBegin(GL_QUADS);
      // Beginning of front
      glNormal3fv(@FrontNormal);
      glVertex3fv(@FrontDownLeft);
      glVertex3fv(@FrontDownRight);
      glVertex3fv(@FrontUpRight);
      glVertex3fv(@FrontUpLeft);
      // End of front
    glEnd;


    glBegin(GL_QUADS);
      // Beginning of left
      glNormal3fv(@LeftNormal);
      glVertex3fv(@FrontDownLeft);
      glVertex3fv(@FrontUpLeft);
      glVertex3fv(@BackUpLeft);
      glVertex3fv(@BackDownLeft);
      // End of left
    glEnd;

    glBegin(GL_QUADS);
      // Beginning of right
      glNormal3fv(@RightNormal);
      glVertex3fv(@FrontDownRight);
      glVertex3fv(@FrontUpRight);
      glVertex3fv(@BackUpRight);
      glVertex3fv(@BackDownRight);
      // End of right
    glEnd;

    glBegin(GL_QUADS);
      // Beginning of up
      glNormal3fv(@UpNormal);
      glVertex3fv(@FrontUpRight);
      glVertex3fv(@FrontUpLeft);
      glVertex3fv(@BackUpLeft);
      glVertex3fv(@BackUpRight);
      // End of up
    glEnd;

    glBegin(GL_QUADS);
      // Beginning of down
      glNormal3fv(@DownNormal);
      glVertex3fv(@FrontDownRight);
      glVertex3fv(@FrontDownLeft);
      glVertex3fv(@BackDownLeft);
      glVertex3fv(@BackDownRight);
      // End of down
    glEnd;

    glBegin(GL_QUADS);
      // Beginning of back
      glNormal3fv(@BackNormal);
      glVertex3fv(@BackDownLeft);
      glVertex3fv(@BackDownRight);
      glVertex3fv(@BackUpRight);
      glVertex3fv(@BackUpLeft);
      // End of back
    glEnd;
  end;

  procedure TFMainForm.SetupGL;
  begin
    glClearColor(0.3,0.4,0.7,0.0);
    glEnable(GL_DEPTH_TEST);
    glEnable(GL_SMOOTH);
    glDepthFunc(GL_LEQUAL);
    glEnable(GL_TEXTURE_2D);

    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity;
    gluLookAt(-2, 3, -3, 0,0,0, 0,1,0);
    uzglLightEnable;
    LightPos[0]:=0;
    LightPos[1]:=0;
    LightPos[2]:=1;
    LightPos[3]:=1;
  end;

  procedure TFMainForm.uzglLightEnable;
  begin
    glEnable(GL_LIGHTING);
    glEnable(GL_LIGHT0);
    glEnable(GL_COLOR_MATERIAL);
  end;

  procedure TFMainForm.Render;
  begin
    glClear(GL_COLOR_BUFFER_BIT or GL_DEPTH_BUFFER_BIT);

    glMatrixMode(GL_MODELVIEW);
    glPushMatrix;
    glRotatef(XRot,1,0,0);
    uzglCube;

    if FTransformLights then
    begin
      glLightfv(GL_LIGHT0, GL_POSITION,@LightPos);
      glPopMatrix;
    end
    else
    begin
      glPopMatrix;
      glLightfv(GL_LIGHT0, GL_POSITION,@LightPos);
    end;

    SwapBuffers(dc);

    XRot:=XRot+1;
  end;

  procedure TFMainForm.IdleHandler(Sender : TObject; var Done : Boolean);
  begin
    Render;
    Sleep(25);
    Done:=false;
  end;

  procedure TFMainForm.FormCreate(Sender: TObject);
  begin
    dc:=GetDC(Handle);

    if not InitOpenGL then
                      begin
                      ShowMessage('????????... ????????????? ???????????');
                      Application.Terminate;
                      end;
    hrc:=CreateRenderingContext       (dc,
                                       [opDoubleBuffered],
                                       32,
                                       24,
                                       8,
                                       0,
                                       0,
                                       0);

    ActivateRenderingContext(dc,hrc);
    FTransformLights:=false;
    SetupGL;
    Application.OnIdle:=IdleHandler;

    FMainForm.OnResize(self);
  end;



  procedure TFMainForm.FormResize(Sender: TObject);
    var tmpBool:boolean;
  begin
    glViewport(0,0,ClientWidth,ClientHeight);

    glMatrixMode(GL_PROJECTION);
    glLoadIdentity;
    gluPerspective(45.0,ClientWidth/ClientHeight,NearClipping,FarClipping);


    idleHandler(Sender, tmpBool);
  end;


  procedure TFMainForm.FormDestroy(Sender: TObject);
  begin
    DeactivateRenderingContext;
    DestroyRenderingContext(hrc);
    ReleaseDC(Handle,dc);
  end;


  procedure TFMainForm.FormKeyPress(Sender: TObject; var Key: Char);
  begin

    case key of
    'q':LightPos[0]:=LightPos[0]+0.1;
    'a':LightPos[0]:=LightPos[0]-0.1;
    'w':LightPos[1]:=LightPos[1]+0.1;
    's':LightPos[1]:=LightPos[1]-0.1;
    'e':LightPos[2]:=LightPos[2]+0.1;
    'd':LightPos[2]:=LightPos[2]-0.1;
    'x':FTransformLights:=NOT FTransformLights;
    end;
  end;

end.

Upvotes: 6

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