// Set color and depth clear value
glClearDepth(1.f);
glClearColor(0.f, 0.f, 0.f, 0.f);
// Enable Z-buffer read and write
glEnable(GL_DEPTH_TEST);
glDepthMask(GL_TRUE);
// Setup a perspective projection
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluPerspective(90.f, 1.f, 1.f, 500.f);