multiple views Flicker

hey, i’am trying to get my OpenGL window divided into two view so i used glviewport(); but after running the program the views flicker and i want to know what is the problem to solve it , here is a part of my display function just need a solution to the flickering problem

 glViewport(0,0,GetSystemMetrics(SM_CXFULLSCREEN),GetSystemMetrics(SM_CYFULLSCREEN)-350);
	glLoadIdentity();	
	glClear(GL_COLOR_BUFFER_BIT);
	glMatrixMode(GL_PROJECTION);
	gluOrtho2D(0.0, 840.0, 0.0, 380.0);
        Drawpanel();
        glViewport(0,GetSystemMetrics(SM_CYFULLSCREEN)-350,GetSystemMetrics(SM_CXFULLSCREEN),GetSystemMetrics(SM_CYFULLSCREEN)-(GetSystemMetrics(SM_CYFULLSCREEN)-350));
        glMatrixMode(GL_PROJECTION);
	glLoadIdentity();
	gluPerspective(60.0,1.0,1,20000000);
	glMatrixMode(GL_MODELVIEW);
	glDepthFunc(GL_LEQUAL);								// The Type Of Depth Testing To Do
	glEnable(GL_DEPTH_TEST);							// Enables Depth Testing
	glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);
	glLoadIdentity();
	plane();
	updateCamera();
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
        runway();
	glDrawSky();
	glDrawSun();
	glDrawTerrain();

does it flicker always or only when u use glviewport() or something else

possible causes of flicker

not using a doublebuffer window
not enabling vsync

Hi,

glClear() is not affected by glViewPort().
I suggest you move the glClear() before the two viewports are rendered.

Ido