glClearColor levée exception TOpenGLComponent Lazarus

Question

J'utilise Lazarus (sous Linux) S'il vous plaît, aidez-moi. J'ai un problème. J'ai installer LasOpenGLContext. Il y a "Contrôle OpenGL" sur le panneau des composants. Et je souhaite dessiner un simple cube. Mais je ne peux pas le faire. Je reçois raised an exception class 'External:SIGSEGV' Quel est le problème? S'il vous plaît, si des idées.

unit Ex1; 

{$mode objfpc}{$H+} 
{$LinkLib GL} 
interface 

uses 
    Classes, SysUtils, FileUtil, OpenGLContext, Forms, Controls, Graphics, gl, glu, Glut, 
    Dialogs, ExtCtrls, LazOpenGLContext, LCLType; 

type 

    { Tfrm } 

    Tfrm = class(TForm) 
    OpenGLControl1: TOpenGLControl; 
    Timer: TTimer; 
    procedure FormCreate(Sender: TObject); 
    procedure TimerTimer(Sender: TObject); 
    private 
    { private declarations } 
    public 
    cube_rotation: GLFloat; 
    Speed:   Double; 
    { public declarations } 
    end; 

var 
    frm: Tfrm; 

implementation 

{$R *.lfm} 

{ Tfrm } 

procedure Tfrm.FormCreate(Sender: TObject); 
begin 

    glClearColor(1.0, 1.0, 1.0, 1.0); // here brakepoint raised an exception class 'External:SIGSEGV' 
    glClear(GL_COLOR_BUFFER_BIT or GL_DEPTH_BUFFER_BIT); 
    glEnable(GL_DEPTH_TEST); 

    glMatrixMode(GL_PROJECTION); 
    glLoadIdentity(); 
    gluPerspective(45.0, double(width)/height, 0.1, 100.0); 
    glMatrixMode(GL_MODELVIEW); 
    glLoadIdentity(); 

    glTranslatef(0.0, 0.0,-6.0); 
    glRotatef(cube_rotation, 1.0, 1.0, 1.0); 

    glBegin(GL_QUADS); 
      glColor3f(0.0,1.0,0.0);      
      glVertex3f(1.0, 1.0,-1.0);     
      glVertex3f(-1.0, 1.0,-1.0);     
      glVertex3f(-1.0, 1.0, 1.0);     
      glVertex3f(1.0, 1.0, 1.0);     
    glEnd(); 
    glBegin(GL_QUADS); 
      glColor3f(1.0,0.5,0.0);        
      glVertex3f(1.0,-1.0, 1.0);     
      glVertex3f(-1.0,-1.0, 1.0);     
      glVertex3f(-1.0,-1.0,-1.0);     
      glVertex3f(1.0,-1.0,-1.0);     
    glEnd(); 
    glBegin(GL_QUADS); 
      glColor3f(1.0,0.0,0.0);        
      glVertex3f(1.0, 1.0, 1.0);     
      glVertex3f(-1.0, 1.0, 1.0);     
      glVertex3f(-1.0,-1.0, 1.0);     
      glVertex3f(1.0,-1.0, 1.0);     
    glEnd(); 
    glBegin(GL_QUADS); 
      glColor3f(1.0,1.0,0.0);        
      glVertex3f(1.0,-1.0,-1.0);     
      glVertex3f(-1.0,-1.0,-1.0);     
      glVertex3f(-1.0, 1.0,-1.0);     
      glVertex3f(1.0, 1.0,-1.0);     
    glEnd(); 
    glBegin(GL_QUADS); 
      glColor3f(0.0,0.0,1.0);        
      glVertex3f(-1.0, 1.0, 1.0);     
      glVertex3f(-1.0, 1.0,-1.0);     
      glVertex3f(-1.0,-1.0,-1.0);     
      glVertex3f(-1.0,-1.0, 1.0);     
    glEnd(); 
    glBegin(GL_QUADS); 
      glColor3f(1.0,0.0,1.0);        
      glVertex3f(1.0, 1.0,-1.0);     
      glVertex3f(1.0, 1.0, 1.0);     
      glVertex3f(1.0,-1.0, 1.0);     
      glVertex3f(1.0,-1.0,-1.0);     
    glEnd(); 

    cube_rotation += 5.15 * Speed; 


    OpenGLControl1.SwapBuffers; 
end; 

procedure Tfrm.TimerTimer(Sender: TObject); 
begin 

end; 

end. 

Answer 1

Vous semblez manquer la création de contexte OpenGL. Sans cela, chaque appel OpenGL peut planter votre programme. Je ne l'ai pas utilisé Lazare, mais selon their website le code pour créer un contexte pourrait être la suivante:

procedure TForm1.FormCreate(Sender: TObject); 
begin 
    GLbox:= TOpenGLControl.Create(Form1); 
    GLbox.AutoResizeViewport:= true; 
    GLBox.Parent := self; 
    GLBox.MultiSampling:= 4; 
    GLBox.Align := alClient; 
    GLBox.OnPaint := @GLboxPaint; //for "mode delphi" this would be "GLBox.OnPaint := GLboxPaint" 
    GLBox.invalidate; 
end;