I am trying a simple Qt Application using OpenGL to display a triangle on screen.

But my QGLWidget is not display anything except the background color.

Here is the code :

Qt Code: 
  1. intializeGL () { } // Blank for now. not initializing any states
  2.  
  3. resizeGL () {
  4. 	if (h==0)			// Prevent A Divide By Zero By
  5. 	{
  6. 		h=1;			// Making Height Equal One
  7. 	}
  8.  
  9. 	glViewport(0,0,w,h);	// Reset The Current Viewport
  10.  
  11. 	glMatrixMode(GL_PROJECTION);		// Select The Projection Matrix
  12. 	glLoadIdentity();					// Reset The Projection Matrix
  13.  
  14. 	// Calculate The Aspect Ratio Of The Window
  15. 	gluPerspective(45.0f,(GLfloat)w/(GLfloat)h,0.1f,100.0f);
  16.  
  17. 	glMatrixMode(GL_MODELVIEW);			// Select The Modelview Matrix
  18. 	glLoadIdentity();			        // Reset The Modelview Matrix
  19. }
  20.  
  21. paintGL ()
  22. {
  23.     clearWindow();     // Clear window to black
  24.  
  25.        glColor3f (1.0, 1.0, 1.0);
  26. 	glBegin(GL_TRIANGLES);						// Drawing Using Triangles
  27. 		glVertex3f( 0.0f, 1.0f, 0.0f);					// Top
  28. 		glVertex3f(-1.0f,-1.0f, 0.0f);					// Bottom Left
  29. 		glVertex3f( 1.0f,-1.0f, 0.0f);					// Bottom Right
  30. 	glEnd();								// Finished Drawing The Triangle
  31. }
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It is a simple enough code downloaded from Nehe. But the triangle is not being displayed at all!! can someone help please?